Track Tuning for Overall Handling Balance

Dec 06, 2025, 06:44 PM

Track Tuning for Overall Handling Balance

Welcome,
I promise to post advice only when I have significant knowledge & experience on the topic. Please don't be offended if you ask me to speculate & I decline. I don't like to guess, wing it or BS on things I don't know. I figure you can wing it without my input, so no reason for me to wing it for you.

A few guidelines I'm asking for this thread:
1. I don't enjoy debating the merits of tuning strategies with anyone that thinks it should be set-up or tuned another way. It's not fun or valuable for me, so I simply don't do it. Please don't get mad if I won't debate with you.

2. If we see it different ... let's just agree to disagree & go run 'em on the track. Arguing on an internet forum just makes us all look stupid. Besides, that's why they make race tracks, have competitions & then declare winners & losers.

3. To my engineering friends ... I promise to use the wrong terms ... or the right terms the wrong way. Please don't have a cow.

4. To my car guy friends ... I promise to communicate as clear as I can in "car guy" terms. Some stuff is just complex or very involved. If I'm not clear ... call me on it.

5. I type so much, so fast, I often misspell or leave out words. Ignore the mistakes if it makes sense. But please bring it up if it doesn't.

6. I want people to ask questions. That's why I'm starting this thread ... so we can discuss & learn. There are no stupid questions, so please don't be embarrassed to ask about anything within the scope of the thread.

7. If I think your questions ... and the answers to them will be valuable to others ... I want to leave it on this thread for all of us to learn from. If your questions get too specific to your car only & I think the conversation won't be of value to others ... I may ask you to start a separate thread where you & I can discuss your car more in-depth.

8. Some people ask me things like "what should I do?" ... and I can't answer that. It's your hot rod. I can tell you what doing "X" or "Y" will do and you can decide what makes sense for you.

9. It's fun for me to share my knowledge & help people improve their cars. It's fun for me to learn stuff. Let's keep this thread fun.

10. As we go along, I may re-read what I wrote ... fix typos ... and occasionally, fix or improve how I stated something. When I do this, I will color that statement red, so it stands out if you re-skim this thread at some time too.

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Let's Clarify the Cars We're Discussing:
We're going to keep the conversation to typical full bodied Track & Road Race cars ... front engine, rear wheel drive ... with a ride height requirement of at least 1.5" or higher. They can be tube chassis or oem bodied cars ... straight axle or IRS ... with or without aero ... and for any purpose that involves road courses or autocross.

But if the conversation bleeds over into other types of cars too much ... I may suggest we table that conversation. The reason is simple, setting up & tuning these different types of cars ... are well ... different. There are genres of race cars that have such different needs, they don't help the conversation here.

In fact, they cloud the issue many times. If I hear one more time how F1 does XYZ ... in a conversation about full bodied track/race cars with a X" of ride height ... I may shoot someone. Just kidding. I'll have it done. LOL

Singular purpose designed race cars like Formula 1-2-3-4, Formula Ford, F1600, F2000, etc, Indy Cars, IMSA Prototypes, Open Wheel Midgets & Sprint Cars. First, none of them have a body that originated as a production car. Second, they have no ride height rule, so they run almost on the ground & do not travel the suspension very far. Formula 1-2-3-4, Formula Ford, F1600, F2000, etc, Indy Cars, IMSA Prototypes are rear engine. The Open Wheel Midgets & Sprint Cars are front engine & run straight axles in front.

I have a lot of experience with these cars & their suspension & geometry needs are VERY different than full bodied track & road race cars with a significant ride height. All of them have around 60% rear weight bias. That changes the game completely. With these cars we're always hunting for more REAR grip, due to the around 60%+/- rear weight bias.

In all my full bodied track & road race cars experience ... Stock Cars, Road Race GT cars, TA/GT1, etc. ... with somewhere in the 50%-58% FRONT bias ... we know we can't go any faster through the corners than the front end has grip. So, what we need to do, compared to Formula 1-2-3-4, Formula Ford, F1600, F2000, etc, Indy Cars, IMSA Prototypes, Open Wheel Midgets & Sprint Cars, is very different.

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Before we get started, let's get on the same page with terms & critical concepts.

Shorthand Acronyms
IFT = Inside Front Tire
IRT = Inside Rear Tire
OFT = Outside Front Tire
ORT = Outside Rear Tire
*Inside means the tire on the inside of the corner, regardless of corner direction.
Outside is the tire on the outside of the corner.

LF = Left Front
RF = Right Front
LR = Left Rear
RR = Right Rear
ARB = Anti-Roll Bar (Sway Bar)
FLLD = Front Lateral Load Distribution
RLLD = Rear Lateral Load Distribution
TRS = Total Roll Stiffness
LT = Load Transfer
RA = Roll Angle
RC = Roll Center
CG = Center of Gravity
CL = Centerline
FACL = Front Axle Centerline
RACL = Rear Axle Centerline
UCA = Upper Control Arm
LCA = Lower Control Arm
LBJ = Lower Ball Joint
UBJ = Upper Ball Joint
BJC = Ball Joint Center
IC = Instant Center is the pivot point of a suspension assembly or "Swing Arm"
CL-CL = Distance from centerline of one object to the centerline of the other
KPI = King Pin Inclination, an older term for the angle of the ball joints in relation to the spindle
SAI = Steering Angle Inclination, a modern term for the angle of the ball joints in relation to the spindle

TERMS:
Roll Centers = Cars have two Roll Centers ... one as part of the front suspension & one as part of the rear suspension, that act as pivot points. When the car experiences body roll during cornering ... everything above that pivot point rotates towards the outside of the corner ... and everything below the pivot point rotates the opposite direction, towards the inside of the corner.

Center of Gravity = Calculation of the car's mass to determine where the center is in all 3 planes. When a car is cornering ... the forces that act on the car to make it roll ... act upon the car's Center of Gravity (CG). With typical production cars & "most" race cars, the CG is above the Roll Center ... acting like a lever. The distance between the height of the CG & the height of each Roll Center is called the "Moment Arm." Think of it a lever. The farther apart the CG & Roll Center are ... the more leverage the CG has over the Roll Center to make the car roll.

Instant Center is the point where a real pivot point is, or two theoretical suspension lines come together, creating a pivot arc or swing arm.

Swing Arm is the length of the theoretical arc of a suspension assembly, created by the Instant Center.

Static Camber is the tire angle (as viewed from the front) as the car sits at ride height. Straight up, 90 degrees to the road would be zero Camber. Positive Camber would have the top of tire leaned outward, away from the car. Negative Camber would have the top of tire leaned inward, towards the center of the car.

Camber Gain specifically refers to increasing negative Camber (top of wheel & tire leaning inward, towards the center of the car) as the suspension compresses under braking & cornering.

Total Camber is the combination of Static Camber & Camber Gain ... under braking, in dive with no roll & no steering, as well as the Dynamic Camber with chassis roll & steering.

Dynamic Camber refers to actual angle of the wheel & tire (top relative to bottom) ... compared to the track surface ... whit the suspension in dive, with full chassis roll & a measure of steering. In others, dynamically in the corner entry. For our purposes, we are assuming the car is being driven hard, at its limits, so the suspension compression & chassis/body roll are at their maximum.

Static Caster is the spindle angle (viewed from the side with the wheel off). Straight up, 90 degrees to the road would be zero Caster. Positive Caster would have the top of spindle leaned back toward to cockpit. Negative Caster would have the top of spindle leaned forward towards the front bumper.

Caster Gain is when the Caster angle of the spindle increases (to the positive) as the suspension is compressed, by the upper ball joint migrating backwards and/or the lower ball joint migrating forward ... as the control arms pivot up. This happens when the upper and/or lower control arms are mounted to create Anti-dive. If there is no Anti-dive, there is no Caster Gain. If there is Pro-Dive, there is actually Caster loss.

Anti-Dive is the mechanical leverage to resist or slow compression of the front suspension (to a degree) under braking forces. Anti-dive can be achieved by mounting the upper control arms higher in the front & lower in the rear creating an angled travel. Anti-dive can also be achieved by mounting the lower control arms lower in the front & higher in the rear, creating an angled travel. If both upper & lower control arms were level & parallel, the car would have zero Anti-dive.

Pro-Dive is the opposite of Anti-dive. It is the mechanical leverage to assist or speed up compression of the front suspension (to a degree) under braking forces. Provide is achieved by mounting the upper control arms lower in the front & higher in the rear, creating the opposite angled travel as Anti-Dive. Pro-dive can also be achieved by mounting the lower control arms higher in the front & lower in the rear, creating the opposite angled travel as Anti-Dive.

Split is the measurement difference in two related items. We would say the panhard bar has a 1" split if one side was 10" & the other side 11". If we had 1° of Pro-Dive on one control arm & 2° of Anti-Dive on the other, we would call that a 3° split. If we have 8° of Caster on one side & 8.75° on the other, that is a .75° split.

Scrub Radius = A car's Scrub Radius is the distance from the steering axis line to tread centerline at ground level. It starts by drawing a line through our upper & lower ball joints, to the ground, that is our car's steering axis line. The dimension, at ground level, to the tire tread centerline, is the Scrub Radius. The tire's contact patch farthest from the steering axis loses grip earliest & most during steering. This reduces the tire's grip on tight corners. The largest the Scrub Radius, the more pronounced the loss of grip is on tight corners. Reducing the Scrub Radius during design increases front tire grip on tight corners.

Baseline Target is the package of information about the car, like ride height, dive travel, Roll Angle, CG height, weight, weight bias, tires & wheel specifications, track width, engine power level, estimated downforce, estimated max corner g-force, etc. We call it "Baseline" ... because it's where we're starting at & "Target" because these key points are the targets we're aiming to achieve. We need to work this package of information prior to chassis & suspension design, or we have no target.

Total Roll Stiffness (aka TRS) is the mathematical calculation of the "roll resistance" built into the car with springs, Sway Bars, Track Width & Roll Centers. Stiffer springs, bigger Sway Bars, higher Roll Centers & wider Track Widths make this number go UP & the Roll Angle of the car to be less. "Total Roll Stiffness" is expressed in foot-pounds per degree of Roll Angle ... and it does guide us on how much the car will roll.

Front Lateral Load Distribution & Rear Lateral Load Distribution (aka FLLD & RLLD):
FLLD/RLLD are stated in percentages, not pounds. The two always add up to 100% as they are comparing front to rear roll resistance split. Knowing the percentages alone, will not provide clarity as to how much the car will roll ... just how the front & rear roll in comparison to each other. If the FLLD % is higher than the RLLD % ... that means the front suspension has a higher resistance to roll than the rear suspension ... and therefore the front of the car runs flatter than the rear of the suspension ... which is the goal.

Roll is the car chassis and body "rolling" on its Roll Axis (side-to-side) in cornering.

Roll Angle is the amount the car "rolls" on its Roll Axis (side-to-side) in cornering, usually expressed in degrees.

Dive is the front suspension compressing under braking forces.

Full Dive is the front suspension compressing to a preset travel target, typically under threshold braking. It is NOT how far it can compress.

Rise = Can refer to either end of the car rising up.

Squat = Refers to the car planting the rear end on launch or under acceleration.

Pitch = Fore & aft body rotation. As when the front end dives & back end rises under braking or when the front end rises & the back end squats under acceleration.

Pitch Angle is the amount the car "rotates" fore & aft under braking or acceleration, usually expressed by engineers in degrees & in inches of rise or dive by Racers.

Diagonal Roll is the combination of pitch & roll. It is a dynamic condition. On corner entry, when the Driver is both braking & turning, front is in dive, the rear may, or may not, have rise & the body/chassis are rolled to the outside of the corner. In this dynamic state the outside front of the car is lowest point & the inside rear of the car is the highest point.

Track Width is the measurement center to center of the tires' tread, measuring both front or rear tires.

Tread Width is the measurement outside to outside of the tires' tread. (Not sidewall to sidewall)

Tire Width is the measurement outside to outside of the sidewalls. A lot of people get these confused & our conversations get sidelined.

Floating typically means one component is re-engineered into two components that connect, but mount separate. In rear ends, a "Floater" has hubs that mount & ride on the axle tube ends, but is separate from the axle itself. They connect via couplers. In brakes, a floating caliper or rotor means it is attached in a way it can still move to some degree.

Decoupled typically means one component is re-engineered into two components that connect, but ACT separately. In suspensions, it typically means one of the two new components perform one function, while the second component performs a different function.

Spring Rate = Pounds of linear force to compress the spring 1". If a spring is rated at 500# ... it takes 500# to compress it 1"

Spring Force = Total amount of force (weight and/or load transfer) on the spring. If that same 500# spring was compressed 1.5" it would have 750# of force on it.

Sway Bar, Anti-Sway Bar, Anti Roll Bar = All mean the same thing. Kind of like "slim chance" & "fat chance."

Sway Bar Rate = Pounds of torsional force to twist the Sway Bar 1 inch at the link mount on the control arm.

Rate = The rating of a device often expressed in pounds vs distance. A 450# spring takes 900# to compress 2".

Rate = The speed at which something happens, often expressed in time vs distance. 3" per second. 85 mph. * Yup, dual meanings.

Corner Weight = What each, or a particular, corner of the race car weighs when we scale the car with 4 scales. One under each tire.

Weight Bias = Typically compares the front & rear weight bias of the race car on scales. If the front of the car weighs 1650# & the rear weighs 1350# (3000# total) we would say the car has a 55%/45% front bias. Bias can also apply to side to side weights, but not cross weight. If the left side of the car weighs 1560# & the right 1440#, we would say the car has a 52/42 left side bias.

Cross Weight = Sometimes called "cross" for short or wedge in oval track racing. This refers to the comparison of the RF & LR corner weights to the LF & RR corner weights. If the RF & LR corner scale numbers add up to the same as the LF & RR corners, we would say the car has a 50/50 cross weight. In oval track circles, they may say we have zero wedge in the car. If the RF & LR corner scale numbers add up to 1650# & the LF & RR corners add up to 1350#, we would say the car has a 55/45 cross weight. In oval track circles, they may say we have 5% wedge in the car, or refer to the total & say we have 55% wedge in the car.

Grip & Bite = Are my slang terms for tire traction.

Push = Oval track slang for understeer, meaning the front tires have lost grip and the car is going towards the outside of the corner nose first.

Loose = Oval track slang for oversteer meaning the rear tires have lost grip and the car is going towards the outside of the corner tail first.

Tight is the condition before push, when the steering wheel feels "heavy" ... is harder to turn ... but the front tires have not lost grip yet.

Free is the condition before loose, when the steering in the corner is easier because the car has "help" turning with the rear tires in a slight "glide" condition.

Good Grip is another term for "balanced" or "neutral" handling condition ... meaning both the front & rear tires have good traction, neither end is over powering the other & the car is turning well.

Mean = My slang term for a car that is bad fast, suspension is on kill, handling & grip turned up to 11, etc., etc.

Greedy is when we get too mean with something on the car, too aggressive in our setup & it causes problems.

Steering Turn-In is when the Driver initiates steering input turning into the corner.

Steering Unwind is when the Driver initiates steering input out of the corner.

Steering Set is when the Driver holds the steering steady during cornering. This is in between Steering Turn-In & Steering Unwind.

Roll Thru Zone = The section of a corner, typically prior to apex, where the Driver is off the brakes & throttle. The car is just rolling. The start of the Roll Thru Zone is when the Driver releases the brakes 100%. The end of the Roll Thru Zone is when the Driver starts throttle roll on.

TRO/Throttle Roll On is the process of the Driver rolling the throttle open at a controlled rate.

Trail Braking is the process of the Driver braking while turning into the corner. Typically, at the weight & size of the cars we're discussing here ... the Driver starts braking before Steering Turn-In ... and the braking after that is considered Trail Braking. This is the only fast strategy. Driver's that can't or won't trail brake are back markers.

Threshold Braking = The Driver braking as hard as possible without locking any tires, to slow the car as quickly as possible to the target speed for the Roll Thru Zone. Typically done with very late, deep braking to produce the quickest lap times.

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16 CRITICAL RACE CAR DESIGN CONCEPTS:

A. One of the most important design factors is utilizing all four tires on the track surface for maximum possible adhesion. Shaker Rigs (6, 7 & 8 post rigs) exist to help race car designers, teams & engineers maximize tire contact & loading to the track surface. As a general rule, anything that reduces contact patch and/or tire loading is our enemy & anything that increases contact patch (up to optimum) and/or achieves optimum loading of all four tires is our friend.

B. Weight is our enemy. Lighter race cars do everything better. They turn better. They accelerate better. They decelerate better. They even crash better (safer). They stress all the components less. Building a lighter car allows us to run less heavy duty, lighter suspension components reducing unsprung & rotating mass ... leading to an even lighter, faster race car. Every ounce matters if you are serious about winning.

C. Center of Gravity (aka CG ... aka weight mass) matters ... a lot. The mantra of oval track race car builders when it comes to race car weight is "low, light & left." (More left side weight helps cars turning left.) For road race cars it is "low, light & centered." The goal is to have the lightest race car ... weigh the exact same on all four scales ... with the majority of the mass (CG) low in the car & centered in the cockpit.

When the race series or class has a weight minimum, the Racers that build the car as light as practical, then places weight (lead, steel, tungsten) near the center of the car, down low ... will produce a faster, better handling, safer race car.

D. When we design a race car with a lower center of gravity, it is much easier to drive & can be much faster. A lower center of gravity allows the race car to run flatter through the corners, working all four tires better ... more grip ... more corner speed. A lower center of gravity allows the race car to pitch less (dive & rise) under braking & acceleration, working all four tires better ... more grip ... more corner entry & exit speed. A lower center of gravity makes the race car more stable, higher grip & easier to drive.

E. If we carelessly design a race car with excessive weight (mass) outside the axle centerlines, we're asking for a scary, ill handling, even dangerous handling, race car. Excess weight ahead of the front axle centerline will make the front end of the car swing out when we exceed total tire grip. Big push (understeer) & then nose hard into the outside barrier.

Similar in the rear. Excess weight behind of the rear axle centerline will make the rear end of the car swing out when we exceed total tire grip. Hard loose condition (oversteer) & then back hard into the outside barrier. Designing the race car with as much of its needed mass inside the axle centerlines is critical.

F. Track width is CRITICAL. Racing sanctioning bodies know this & enforce track width rules diligently, because all knowledgeable Racers know that even a small increase in track width can provide a significant advantage. Very similar to having a lower center of gravity ... having a wider track width allows the race car to run flatter through the corners, working all four tires better ... more grip ... more corner speed. A wider track width makes the race car more stable, higher grip & easier to drive.

With exception for tight, narrow autocross courses, designing the race car with the widest track width possible is the goal. Widening the car body, or building a wider car body, to achieve the maximum track width is an advantage. A wider track width makes the race car more stable, higher grip, with more corner speed & easier to drive.

G. With the lowest CG possible, the roll centers also need to be low. Ideally the front roll center is at 0" ground level in full dive at threshold braking. The rear roll center needs to be as low as is practical, while producing a roll axis that is optimum for the particular car to have neutral, balanced, high grip handling through all corners of the course.

H. Unsprung weight is everything not supported by the springs. In the front this includes half the control arms, tie rods & shocks & all of the tires, wheels, lugs, brake rotors, calipers, mounts, brake shrouds, uprights & hubs ... plus a portion of the brake cooling ducting. If we have IRS in the rear, the list is the same. If we run a straight axle rear, the list includes half the suspension links & shocks & all of the tires, wheels, lugs, brake rotors, caliper, mounts, brake shrouds, rear axle & hubs ... plus a portion of any brake cooling ducting.

Lighter unsprung weight allows the suspension to react & respond quicker to irregular track surface input, providing a higher % of loaded tire contact & grip. Lighter unsprung weight allows the suspension to react & respond quicker to Driver inputs & increases what the Driver feels in the race car.

I. Of the unsprung weight, the tires, wheels, lugs, brake rotors & hubs are ROTATING WEIGHT. Reducing rotating mass is even more critical than reducing unsprung weight. Accelerating & decelerating a heavier rotating mass take much more time. Said another way, lightening the rotating mass makes the car accelerate & decelerate quicker, producing quicker lap times.

J. The design structure of every component affects how well that component handles the forces inflicted upon it. The challenge is building lightweight chassis & components without having failures, or reduction in grip due to flex.

K. The degree of chassis rigidity ... and where it is ... needs to be designed into the car from the start. If a race car chassis is too flexible, the race car will have less grip, be less responsive to tuning changes & have a wider tuning sweet spot. If a race car chassis is too rigid, the race car will have more grip, be more responsive to tuning changes & have a narrower tuning sweet spot.

Race cars that are heavier, more powerful and/or capable of higher cornering g forces ... require more rigidity for optimum track performance. Race cars that are lighter, less powerful and/or capable of lower cornering g forces ... require less rigidity for optimum track performance.

L. Where the rigidity is designed into the chassis matters as well. Drag cars load the rear suspension significantly more than the front, so the rear of the chassis needs the majority of the chassis rigidity. Road race & oval tracks race cars load the front suspension significantly more than the rear, so the front of the chassis needs the majority of the chassis rigidity. Chassis rigidity designed into the car, needs to be tailored to the direction & location of forces seen dynamically.

M. Aero drag matters in road racing, but less than you may think. In high powered race cars on road courses, aero downforce is way more important than how much aero drag the race car has. The road race car that has more aero downforce, even with a bit more drag, will be the superior performer. With that said, we don't want unnecessary aero drag.

We want to eliminate & reduce all the aero drag possible, just not to the point of sacrificing aero downforce or track width. Yes, a wider track width & wider front end will create more frontal area & aero drag. The performance advantage of track width trumps aero drag on road courses.

The exception, to these aero rules, is super low powered cars where aero drag is more of a hinderance.

N. The suspension strategy that includes the target ride height, dive travel (under braking) & roll angle (when cornering) needs to be decided BEFORE the chassis & suspension are designed. There are a variety of reasons why, but the simple ones are ground clearance & camber gain.

If we design an optimal high travel suspension, for example 3"-4" of dive, we may utilize long control arms to slow the camber during dive. This way we can run optimal static camber & achieve the optimal camber gain. If we later decide to run a low travel suspension, for example 1"-1.5" of dive, the long control arms reduce the amount of camber gain can achieve. This problem would require us to run significantly more than optimal static camber, to arrive at the optimal camber. Conversely, we'll have the reverse problem if we start with a low travel design of shorter control arms & decide to run a high travel strategy ... too much camber gain.

On a different note, we may start with a low travel strategy, for example 1"-1.5" of dive, with a 2.5" ride height & later decide we want to run a high travel strategy, for example 3" of dive. The 2.5" ride height back at the firewall isn't the problem. The 2.25" height we designed the FACL crossmember on the front clip is the problem. If we knew we're going higher travel to start, we would raise the front clip (so to speak) in the design phase, so the FACL crossmember allows that travel.

O. Stiction & friction choices are not often thought about during the design process. But those decisions are often made during design & can be hard to change. Suspension bushings for example. If the chassis & control arms are designed for conventional wide bushings, deciding later to reduce stiction & friction with rod ends can be troublesome. Same with ball joints. Decide this early on.

P. Safety is often thought of as cage design, seat configuration, harnesses, suits, helmets, HANS & nets. These are all good to decide on beforehand as well, for increased protection in a crash. But spindle, hub & bearing failure cause more crashes than any other part on the car.

Race cars that are heavier, more powerful and/or capable of higher cornering g forces ... create higher load on the critical spindle, hub & bearing components. To PREVENT crashes in the first place, work out the load ratings of our spindle, hub & bearing with a safety factor built in.

20 CRITICAL HANDLING CONCEPTS:
1. A car with heavier front weight bias, can go no faster through a corner than the front tires can grip. Balancing the rear tire grip to the front ... for balanced neutral handling ... is relatively easy ... compared to the complexities of optimizing front tire grip.

2. What we do WITH & TO the TIRES ... are the key to performance. Contact patch is the highest priority, with how we load the tires a close second.

3. Geometry design, settings & changes to need to focus on how the tires contact the road dynamically & are loaded.

4. Tires are the only thing that connect the race car to the track surface. Tires play the largest role in race car performance. Rubber in tires hardens rapidly from the day they come out of the mold. Don't run old tires ... unless you want to learn how much it costs to repair race cars. The absolute best performance gain we can make to any race car is fresh, matched tires.

Matching the tires in rubber cure rate, durometer, sizing & sidewall spring rate is key to eliminating handling gremlins that make no sense. The grip level tires are capable of are based on these factors, regardless of tread depth! If the front and/or rear tires aren't matched, we will have different handling issues turning left & right.

5. After the car is built, tires are selected & the geometry is optimum ... most chassis fine tuning is to control the degree of load transfer to achieve the traction goal & handling balance. Dynamic force (load & load transfer) applied to a tire adds grip to that tire. With the exception of aerodynamics, load transfer from tire(s) to tire(s) is the primary force we have to work with.

6. The car's Center of Gravity (CG) acts as a lever on the Roll Center ... to load the tires ... separately front & rear. Higher CG's and/or lower RC's increases Roll Angle, but loads the tires more. Lower CG's and/or higher RC's decrease Roll Angle, but load the tires less. Getting the front & rear of the car to roll on an optimum roll axis is desired. Getting them to roll exactly the same is not the goal, because ...

7. Perpetual goal is to achieve maximum grip & neutral, balanced handling simultaneously through all the corners of the course. To do requires reducing the loading on the inside rear tire (to a degree) ... then increasing the loading of the inside rear tire (to a higher degree) for maximum forward bite on exit. So, on entry & mid-corner, the car needs to roll slightly less in the front to keep both front tires engaged for optimum front end grip, while allowing the car to roll slightly more in the rear to disengage the inside rear tire, to a small degree, to turn better.

For optimal corner exit, the car will have more roll in the front & less in the rear to re-engage the inside rear tire to a higher degree than it was on entry & exit, for maximum forward bite (traction) on exit. This difference is called diagonal roll. This amount differs as speeds & g-forces differ.

8. Modern day tuners do not use the RC height as the primary means of controlling Roll Angle. We use the suspension tuning items as our priority tools to control Roll Angle. We use the RC priority to load the tires optimally. So, to achieve the optimum balance of Roll Angle & working all four tires optimally ... this all has to work with our suspension ... springs, anti-roll bars & shocks ... and track width ... to end up at the optimum Roll Angle for our car & track application.

9. Sway Bars primarily control how far the front or rear suspension (and therefore chassis) "rolls" under force, and only secondarily influences the rate of roll. Softer bars allow increased Roll Angle & more load transfer from the inside tires to the outside tires. Stiffer bars reduce Roll Angle, keeping the car flatter & less load transfer from the inside tires to the outside tires.

10. Springs primarily control how far a suspension corner travels under force, and only secondarily influences the rate of travel. Shocks primarily control the rate of suspension corner travel under force, and only secondarily have influence on how far.

11. Springs, shocks & sway bars need to work together "as a team." Our springs' primary role is controlling dive & rise, also contribute significantly to the car's roll resistance. Our anti-roll bars (sway bars) primary role is controlling roll, but do contribute minutely to dive & rise. Our shocks primarily role is controlling the RATE of these changes, primarily during race car transitions from Driver input, such as braking throttle & steering. They all affect each other, but choose the right tool for the job & we create a harmonious team.

12. The front tires need force, from load transfer on corner entry, to provide front tire GRIP. Too little & the car pushes ... too much & the car is loose on entry. The rear tires need force, from load transfer on corner exit, to provide rear tire GRIP. Too little & the car is loose ... too much & the car pushes on exit.

13. Springs & Sway Bars are agents to load the tires with the force needed to produce maximum grip. Stiffer springs produce the needed force with less travel, whereas softer springs produce the needed force with more travel. Stiffer Sway Bars produce the needed force with less chassis roll, whereas softer Sway Bars produce the needed force with more chassis roll. The tire doesn't care which tool provides the loading force. Ultimately, they combine to produce a wheel load. Our role is to package the right combination for the target dive travel, chassis roll angle & wheel loading we need.

14. Softer front springs allow more compression travel in dive from braking & therefore a lower CG, more front grip & less rear grip. Stiffer front springs reduce compression travel in dive from braking & therefore a higher CG, less front grip & more rear grip. There are pros, cons & exceptions to these rules.

15. Too much Roll Angle overworks the outside tires in corners & underworks the inside tires. Too little Roll Angle underworks the outside tires in a corner. Excessive Roll Angle works the outside tires too much ... may provide an "ok" short run set-up ... but will be "knife edgy" to drive on long runs. The tires heat up quicker & go away quicker. If it has way too much Roll Angle ... the car loses grip as the inside tires are not being properly utilized.

16. Too little Roll Angle produces less than optimum grip. The car feels "skatey" to drive ... like it's "on top of the track." The outside tires are not getting worked enough, therefore not gripping enough. Tires heat up slower & car gets better very slowly over a long run as tires Gain heat.

17. A lower chassis Roll Angle works both sides of the car's tires "closer to even" ... within the optimum tire heat range ... providing a consistent long run set-up & optimum cornering traction, providing the fastest, most drivable race car.

18. Higher Roll Angles work better in tight corners but suffer in high speed corners. Lower Roll Angles work better in high speed corners but suffer in tight corners. The goal on a road course with various tight & high speed corners ... is to find the best balance & compromise that produces the quickest lap times. Smart Tuners use Roll Centers & Aero to achieve this.

19. Tuning is NOT linear two directions with stops at the ends. A car can be loose because it has too little Roll Angle in the rear & is not properly working the outside rear tire. A car can be loose because it has too much Roll Angle in the rear & is not properly working the inside rear tire.

A race car can be pushy because it has too little Roll Angle in the front & is not properly working the outside front tire. A race car can be pushy because it has too much Roll Angle in the front & is not properly working the inside front tire.

20. Don't forget the role & effects the engine, gears, brakes, Driver & track conditions each have on handling.

Apr 13, 2026, 06:13 PM

OKAY ... Let's Talk Track Tuning for Overall Handling Balance

To start, I recopied these handling conditions & their definitions, from the master list above.

Push = Oval track slang for understeer, meaning the front tires have lost grip and the car is going towards the outside of the corner nose first.

Loose = Oval track slang for oversteer meaning the rear tires have lost grip and the car is going towards the outside of the corner tail first.

Tight is the condition before push, when the steering wheel feels "heavy" ... is harder to turn ... but the front tires have not lost grip yet.

Free is the condition before loose, when the steering in the corner is easier because the car has "help" turning with the rear tires in a slight "glide" condition.

Let's define "Overall Handling Balance." "Balance," "Good Grip" or "Neutral Handling" all are terms that mean both the front & rear tires have good traction, neither end is over powering the other & the car is turning well. Both the car & driver are happy.

What we not going to cover here in this thread is how to increase overall grip. That is a different forum thread. Nor are we discussing how to increase grip on one end of the car. We are talking about managing the grip the car has on all 4 tires, to make it brake, turn & accelerate well. Or at least to the best the compromise of those 3 are possible.

We will be talking about shifting grip fore & aft ... from front to rear, & rear to front ... to achieve handling balance. We will also be talking about shifting grip diagonally from corner to corner, to achieve handling balance. In most cases, the tuning changes we make do not increase or decrease total grip. We are just shifting it around. There are a few exceptions, where tuning changes actually decrease grip on one end of the car or one corner of the car. And while this may achieve handling balance, it is not good. We don't want to tune ourselves to less total grip. I will outline the items that can do that, so as to avoid them.

Before we get into handling problems & solutions
... I want to share with everyone a viewpoint to make tuning easier ... then outline terms & critical tuning concepts ... so we're on the same page.

Competition cars are COMPLEX. There are literally over 200 AREAS of things to TUNE in the suspension alone. What helps a Tuner/Crew Chief to become more confident is ... knowledge (of course) ... experience (of course) ... knowing what a mechanical change actually effects on track ... and how each tuning change of affects other areas.

But also, as a Tuner/Crew Chief, having a viewpoint that makes all this complexity ...
simpler to understand ... provides clarity & builds confidence.
I have developed many crew chiefs over the years to work with me on my race teams. Teaching them everything they need to master is a long term commitment on my part & theirs. It takes years. But simplifying things help them grasp concepts quicker ... and develops confidence in their tuning decisions.

Let's simplify things first. Remember this little corny phrase: 4x4x2+2
It is short (like an acronym, but using numbers) for ALL the things that competition car Designers, Tuners & Crew Chiefs deal with. There are 4 key areas with 4 major ingredients, operating in 2 worlds ... plus 2 wild cards. 4x4x2+2 is just a simple way to remind us what we're dealing with.

The 4 key areas are: power, braking, handling & aerodynamics (in no particular order.) Obviously these all play a role in the performance of the car ... and in many cases affect each other.

Each Key area has 4 major ingredients that define it & of course affect it.

For power, the 4 major ingredients are:
Airflow
Fuel management
Spark control
Structure Design

For braking, the 4 major ingredients are:
Hydraulics
Leverage
CoF
Structure Design

For handling, the 4 major ingredients are:
Tires
Weight transfer ... to and from tires
Geometry affecting ... the tires
Structure Design

For aerodynamics, the 4 major ingredients are:
Force
Drag
Turbulence
Structure Design

When I said competition cars operate in two worlds, what I really mean is we do a lot of design, set up & tuning to the car in a "static state" ... then go drive it HARD ... and everything is affected & different when the car is in a "dynamic state" on track.
No pun intended, but the 2 wild cards are the track & the driver. The track environment is constantly changing, and good Tuners/Crew Chiefs tune to the changing conditions.

As long as we use human drivers, this will be a variable. Some drivers are more consistent & some less, but none of them are robots, so there will be inconsistencies. Some drivers are learning & improving, some not & even some declining in their abilities, but again, they are not static. Some drivers are more of a wild card than others.

As long as we simply embrace these 4 key areas, understand the 4 major ingredients that define & affect them, remember the car is acting in a dynamic state on track & account for the 2 wild cards ... the job of Tuner/Crew Chief gets more clear, less daunting and making tuning decisions becomes easier, quicker & more confidently.[/b]

Apr 13, 2026, 06:14 PM

Where do I start tuning?

Separate tuning mechanical grip versus aero grip. First, we need to be clear on the difference. Mechanical grip is tire grip created by the chassis, geometry, suspension & steering... with no aerodynamic aids to create grip through downforce.

The chassis part is weight, distribution, center of gravity, track width, etc. The suspension part is springs, sway bars, shocks, control arms, stiction, etc. The geometry includes dynamic front & rear roll centers, camber & caster gain, anti-dive, anti-squat, etc. The steering part includes toe settings, bump steer, Ackerman, steering input, etc. All of these components contribute to the raw handling of the race car & the net result we call mechanical grip.

Aero grip, is additional grip we create by adding aerodynamic aids to create downforce on the car & therefore on the tires. Wings, spoilers, air dams, splitters, diffusers, smooth belly pans, canards, etc. all combine to create downforce in some quantifiable amounts, front, rear & total.

Which do we tune first? This answer should make it clear. Think of the grip in layers. The mechanical grip is the bottom layer & the aero is the top layer. In running your race car, you ALWAYS have the mechanical grip, but you don't always (at lower speeds) have aero grip. So mechanical grip is your FOUNDATION. Aero grip adds a LAYER of GRIP on top of the mechanical grip in the higher speed corners, where you need it, to create more TOTAL GRIP.

Design your car's front aerodynamic aids to create maximum downforce in the front & leave it alone. We don't "tune" to reduce the front downforce in full bodied, front engine cars. We want all we can get up front. Then we balance the aero at the rear of the car. Design & adjust your car's rear aerodynamic aids to create a measure more downforce than you'll ever need.

While driving & tuning for the slower corners of the course, we don't want to crash the car in the faster corners. So, to be safe, we always adjust the rear aero in the shop for more rear downforce than we need. This way, if we start to over drive the fast corners, the car will push & let us know to back off, instead of the rear end stepping out at high speed & ruining our day.

Plan your tuning sessions this way. Start in the slower corners, 40-70 mph, to dial in the suspension to make the race car handle optimum here. We need the mechanical grip ... front & rear ... to be both maximized & balanced ... to be fastest in these slower corners. Ignore total lap times. Utilizing segment timers, as well as driver feedback, is the best method here.

Then we move on to trimming out the rear aero to achieve the most BALANCED total grip we can get in the fastest corners. "Trimming out" means to take out rear downforce a step at a time. All wise racers & teams that run aero, set the rear aero to create a slight "aero push" in the high speed turns. Then they trim it out a step at a time. This is the safe way.

Starting with the car "aero loose" is fu@#ing dumb & a great way to crash the car. When testing a brand new car, always start with max rear downforce & trim it out when tuning.

Lastly, and this is KEY, aero downforce is not an absolute. Airflow is a variable. If we have a headwind, we'll have more downforce. Tail wind? Less downforce. Crosswind? Who knows! Hang on! A wheel jerking Driver can make downforce disappear long enough to crash. With significant aero, the Driver HAS TO BE SMOOTH as glass ... or bad stuff will happen.

Apr 13, 2026, 06:15 PM

The next discussion is broken into 4 parts. This is part 1 of 4.

Diagonal Roll Travel Discussion & Explanation

From the master list above is the definition of Diagonal Roll. [/b]It is the combination of chassis pitch & chassis roll. It is a dynamic condition. On corner entry, when the Driver is both braking & turning, front is in dive, the rear may, or may not, have rise & the body/chassis are rolled to the outside of the corner. In this dynamic state the outside front of the car is lowest point & the inside rear of the car is the highest point.

Diagonal Roll is normal physics with the braking & turning forces we're introducing to the car. Too much Diagonal Roll is bad ... causing a free or loose condition. Too little Diagonal Roll is bad ... causing a tight or push condition. Our job is managing the amount of Diagonal Roll to achieve neutral, balanced, handling, void of those negative conditions. When the Race Drivers says the car is very "drivable" ... I take that to mean they're not fighting the handling gremlins of loose or push.

To achieve the optimum Diagonal Roll for our desired neutral, balanced, handling, you need to get the inside rear tire to disengage ... to a degree. Restated from above ...

If we have too much Diagonal Roll, we're disengaging the inside rear tire TOO MUCH ... creating a free or loose condition. If we don't have enough Diagonal Roll, we're not disengaging the inside rear tire enough ... creating a tight or push condition.

The best, most confident chassis tuners embrace that ... at the track ... we're simply tuning the disengagement & reengagement of the inside rear tire to achieve handling balance. We are "managing" the Diagonal Roll. Understanding this & mastering this are the most important tuning things you need to know. It is so important, I restate or repeat certain concepts throughout this discussion. It is that important.

Let's take these areas one at a time, starting with ...

For Optimum Corner Handling ... You Need to Disengage the Inside Rear Tire
... To a Degree
"Disengage ... to a degree" means we are reducing the load on that inside rear tire. We may ... or may not ... need to reduce the tire's contact patch. But for optimum cornering ability, we need to reduce the grip of the inside rear tire. This is critical to a good handling car on grippy tires & tight corners.

"To a degree" means we are not lifting the tire off the ground completely. We may not even be close. It simply means we are reducing the load & potentially the contact patch on that inside rear tire. "To a degree" also implies ... correctly ... that we want to control how much. This is key. If we do not disengage the inside rear tire enough, we struggle with a tight/pushy car. If we disengage the inside rear tire too much, we now have a loose car to deal with. How much is right? The answer depends on many factors and varies by track, car, set-up & driver. Heck, it will vary throughout the day as track
conditions change.

"Re-engage" means we want to "plant" the inside rear tire hard on corner exit ... to regain & achieve a loaded, full contact patch ... so we have two full tire's worth of contact patch for accelerating. This happens as the driver unwinds the steering wheel. "How much" is determined by suspension geometry, shocks, springs, etc.

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How do we disengage the rear tire to a degree? ... by managing the AMOUNT of Diagonal Roll travel.
Again, Diagonal Roll travel is the combination of roll & pitch. Pitch happens under braking. How much body/chassis pitch we have (typically measured in inches) ... is created by braking g-forces & can be managed with CG height, ride heights, weight bias, spring rates, shock valving, bump stops, anti-dive & aero, as well as the Race Driver's degree of braking.

Roll happens during cornering. How much body/chassis roll we have (typically measured in degrees) is created by cornering g-forces & can be managed with CG height, ride heights, weight bias, spring rates, shock valving, bump stops, sway bar rates, roll centers & track widths, as well as the Race Driver's cornering speed.

Diagonal Roll travel happens during the combination of braking & cornering. Diagonal Roll travel is when the inside rear suspension extends, unloading the inside rear tire "to a degree" ... while compressing the outside front tire farther & loading it more.

Think about the car dynamically on track. When you come up to a corner, you brake first, and the front suspension compresses evenly. A lot of weight has transferred from rear to front. The rear tires have less load & less grip. The front tires have more load & more grip. Now ... you turn into the corner. This doesn't happen "all at once" ... it happens gradually. Let's say it's a right hand corner. When you first move the steering wheel to the right ... weight starts to shift to the left side tires.

Because you're still on the brakes while turning ... the left front tire is now getting more load than any other tire ... and the loading will increase as you turn the steering wheel more and the car turns harder into this right hand corner. If you're running a modern low roll set-up, the inside front tire is still an effective & vital part of the front suspension & grip equation. It's just not doing as much work, or providing as much grip, as the outside front tire.

Make sense so far? If not, please ask questions.

For optimum cornering ability, you need Diagonal Roll to disengage the inside rear tire "to a degree" and load the outside front tire more. The "to a degree" part is critical. As mentioned above, if you disengage the inside rear tire too much, the car is loose on corner entry & middle. If you don't disengage the inside rear tire "enough" the car is tight/pushy in the middle of the corner. (Entry also ... if extreme.)
Tip: You don't "make" Diagonal Roll happen. The natural g-forces caused by braking & turning make the car want to diagonally roll. You simply need to control "how much" with suspension tuning.

The keys to controlling the amount of Diagonal Roll & therefore the degree the inside rear tire disengages:
• Degree of jacking effect
• Difference in front to rear roll angle
• Amount of front end travel combined with the degree of roll angle

Let's take them one at a time

Apr 13, 2026, 06:15 PM

Part 2 of 4

Jacking effect:
When the driver brakes & turns the steering wheel (corner entry) ... the outside front tire leans/tilts/cambers (pick a term) back at the top, toward the inside of the corner, as the suspension on that outside front corner compresses. This helps the outside front tire's contact patch optimize on the track surface. This affect also lets the outside front suspension compress a little farther.

At the same time, the inside front tire leans back at the top, toward the inside of the corner. This helps the inside front tire's contact patch be flatter on the track surface. But the inside front suspension does not compress from this action. The g-forces are not going that direction. In fact, this inside front corner lifts somewhat, loading the suspension the opposite corner (outside rear tire). This action, known as the jacking effect, is de-wedging the suspension & creating a rotational axis for the other two suspension corners.

What we end up with is:
• The outside rear tire & inside front tire acting as a rotational axis for the car.
• Diagonal Roll and load transfer from inside rear suspension & tire to the outside front suspension & tire ... "to a degree."
• De-wedged suspension ... "to a degree."

What really happens when we "de-wedge" the suspension with jacking effect in the corner?
• Dynamically ... the spring loads change.
• The inside front corner & outside rear corner see a dynamic spring force increase, helping to load these tires more.
• If the car was flat on all four tires ... which it is not ... the outside front tire and inside rear tire would see a dynamic spring force decrease.
• But because the g-forces are diagonally rolling the car off the inside rear suspension & tire ... and onto the outside front suspension & tire ... the outside front suspension & tire are loaded more than any corner (so lots of spring force) ... and the inside rear suspension becomes "relaxed" and extended, reducing the spring force & load on that tire.

This jacking effect & de-wedging is a critical process that happens in all race cars when turning. You need this jacking effect to disengage the inside rear tire ... to a degree ... and increase load on the outside front tire ... to assist the car to turn. This de-wedging process is key to any & every track car turning well. If you have too much jacking effect ... the inside rear tire gets disengaged too much ... and the car gets loose in the first 1/3 of the corner. If you have too little jacking effect ... the inside rear tire
does not disengage enough ... and the car pushes in the middle of the corner.

What influences the amount or degree of jacking effect?
The two corners of the suspension that form the rotational axis affect it: The inside front & the outside rear. Most tuners only think about the inside front suspension & tire. The degree of caster & spindle KPI affect the jacking equation. But the KPI & caster only control the dynamic camber angle of the tire & wheel when turned. The scrub radius acts as an amplifier. Caster & KPI have a smaller effect. Scrub radius has a bigger effect. The bigger the scrub radius, the farther the tire & wheel are "out" from the spindle pivot axis ... and the more jacking & lifting occurs at the inside front tire, therefore increasing the dewedging effect and increasing the amount of Diagonal Roll travel.

In the simplest of terms ... more scrub radius disengages the inside rear tire ... to a higher degree. While less scrub radius disengages the inside rear tire ... to a lower degree. Tighter corners need MORE JACKING EFFECT. AutoX needs more jacking effect. Super high speed corners need less jacking effect.

The outside rear suspension plays an often forgotten roll. If the outside rear suspension is too soft ... then it simply compresses more as the inside front tire creates the jacking affect. It absorbs the jacking effect. Realize to have a rotational axis for jacking effect ... the inside front & outside rear need to act as a pivot for the other two corners.

• If the outside rear suspension is softer ... the jacking effect is reduced.
• If the outside rear suspension is stiffer ... the jacking effect is increased.

The combination of rear weight bias, springs, sway bar, roll center, track width & CG ... need to allow just enough rear roll angle to disengage the inside rear tire to a degree ... but high enough to prevent the outside rear suspension from compressing so much that the car loses jacking effect. If the rear is too soft, the car will have insufficient jacking effect, insufficient Diagonal Roll resulting in a tight handling condition. If the rear suspension is way too soft ... the car will actually roll diagonally more onto the
outside rear suspension ... and unload the inside front tire ... resulting in a tight or push condition.

It is the combination of the factors starting the jacking effect (KPI, caster & scrub radius) ... and the factors that influence rear suspension compression (spring, sway bar, RC, CG, track width & weight bias) ... together that ultimately determines how much jacking effect we have. If you have moderate to high scrub radius, you will unfortunately need to run less caster. If you have smaller scrub radius, not only can you run more caster, but you NEED to run more caster, to help the car turn.

Everything is a compromise, but you can achieve the optimum jacking effect with:
• Low caster ... by running a higher scrub radius
• High caster ... by running a lower scrub radius
• Low scrub radius ... by running higher caster
• High scrub radius ... by running lower caster

OK, now what?
• First, don't use KPI, caster & scrub radius as independent jacking effect tuning tools. They affect the tire contact patch.
• Don't simply increase jacking effect, without taking into account how the KPI, caster & scrub radius changes affect everything else.
• Do understand & embrace the jacking effect/de-wedging concept as a part of your total Diagonal Roll tuning approach.
• I recommend you set your KPI, caster & scrub radius for optimum tire contact patch.
• Then achieve the rest of your Diagonal Roll travel with front to rear roll angle difference.
• If you need to increase jacking effect, consider stiffening the rear spring rate.

The optimum set-up that performs best ... is zero scrub radius (dynamically) and high caster ...
typically more caster than the spindle KPI. It is optimum, not because it achieves more jacking effect. It is optimum because the "zero scrub radius" produces the least amount of tire tread squirm & scrub when turned ... and the higher degree of caster is utilized to achieve the optimum contact patch & moderate jacking effect.

This conversation is to help us tune the race car for handling balance. So, to be complete...

Let's talk corner exit ...
As you unwind the steering wheel on corner exit ... you are adding "wedge" back into the suspension to help grip the car for faster acceleration. Frankly, this is one part of why running a late apex line is often quicker in tight, low speed corners. It allows you to get the steering unwound quicker ... which adds more rear tire grip for corner exit.

Two key pieces of information:
1. The more compression travel your front suspension has on corner entry ... the more extension travel your front suspension will have on corner exit ... achieving higher levels of rear tire grip ... for a longer distance ... improving your corner exit acceleration.
2. The more jacking effect your front suspension has on corner entry to de-wedge the car ... the more effect the un-jacking effect has on corner exit ... adding back in a higher degree of wedge as you unwind the steering on corner exit ... achieving higher levels of rear tire grip ... improving your corner exit acceleration.

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Just FYI: The term "jacking" is also used in racing to describe:
The effect the control arms have on jacking the frame down and compressing the spring through additional leverage with high upper control arm angles. The effect shocks having in jacking the car down in ride height ... front, rear, or both ... when they have very soft compression valving & extreme rebound valving at 0" inches per second?

Apr 13, 2026, 06:16 PM

Part 3 of 4

Diagonal Roll angle can not be measured statically with accuracy. If you put the car on scales & turn the wheels, the weights stay the same as the springs absorb the ride height changes. We have "tricked" the car by putting solid rods in place of the shocks, but all you're learning is the concept. No accurate numbers. We can simulate it on a pull down rig, but it requires the front suspension be on coil bind or bump stops. But to be accurate, you need suspension travel numbers from actual track testing.

You can accurately measure it on track with data acquisition & shock sensors on all four corners. As you increase the caster or scrub radius, the amount the outside front tire compresses ... and the amount he inside rear extends ... increases. Frankly, we don't pursue this line of data. We know the concept exists and accept it as a key element. We don't add caster, or reduce caster, to effect the jacking effect. We tune the caster to achieve optimum contact tire patch. Anything different than that will produce slower lap times because the degree of front tire grip goes down.

We also tune the dynamic toe-out (static toe, toe-out gain from bump steer & ackerman all combined) to optimize the slip angle of the inside front tire ... again to optimize the total grip both front tires have.
If you refer back to my earlier fundamental statements, I mentioned you need to get the inside rear tire to disengage ... to a degree ... to achieve optimum turning. As we have been discussing now ... we achieve that through the Diagonal Roll of the car ... with the inside rear lifting & unloading that tire to a degree ... while compressing the outside front tire & loading it more.

The jacking effect helps us achieve that, but in most production body shaped cars ... with 48-56% or more front weight bias ... we "usually" don't tune this with caster or scrub radius changes. Realize they will affect it, but the cons make this line of tuning less than ideal. So what changes can be made to affect the amount of Diagonal Roll ... and therefore to what degree the inside rear tire is being disengaged during cornering?

Anything that makes the front roll angle less than the rear roll angle. Or, said the other way, anything that makes the rear roll angle more the front roll angle. The key here is compressing the front suspension more, without any additional roll angle in the front. Or, in the rear, increase the extension of the rear suspension ... with a little additional roll angle ... coming from the extension of the inside corner, not from compression of the outside rear corner.

Specifically ...
• Softer front springs with a bigger sway bar
• Stiffer rear springs with a smaller (or no) sway bar
• Lower CG's front & rear
• Softer compression valving in the front shocks
• Softer rebound valving in the rear shocks
• Wider rear track width
• Combination of these tuning items.

I only laid out tuning options above to "increase" diagonal roll. Obviously, going the opposite direction will decrease diagonal roll. Like anything in tuning, you can have too much or too little. The key is to tune these items to get the inside rear tire to disengage ... just enough ... to make the car turn easily through the corners. Too little ... and the car is tight or pushy. Too much and the car is loose.
Make sense?

Difference in front to rear roll angle:
Track cars NEED to travel the suspension ... to load certain tires more & others less when cornering ... and there are two proven approaches. At the start of this thread, you probably read about the two common suspension strategies. Conventional strategy utilizes stiffer front springs for less front suspension travel under braking & modest sway bars for a higher roll angle. Modern strategy utilizes softer front springs for higher front suspension travel under braking & very large sway bars for a very low roll angle.

Said simply, conventional rolls more & pitches less. Modern rolls less & pitches more. But regardless of the strategy chosen ... the rear roll angle needs to be slightly more the front angle ... to achieve proper Diagonal Roll and disengagement of the inside rear tire.

Here are two real suspension travel examples in similar cars, with numbers rounded off for easier discussion. (I used these same numbers in a previous discussion in a different forum thread.)

Notes:
• These are shock travel numbers, measured in inches, during braking & turning
• The front shocks are 50" apart, which helps us calculate front roll angle
• The rear shocks are 58" apart, which helps us calculate rear roll angle
• + means the shock extended
• - means the shock compressed
• This is a RH corner, for a LH corner, the numbers simply reverse
• These roll angle degrees are "close" but don't account for outside tire squish.

A. Conventional Low Front Travel/High Roll Set-up
LF -1.500" ... RF +1.000" ... Difference 2.500" ... Front Roll Angle 2.86°
LR -1.875" ... RR +1.375" ... Difference 3.000" ... Rear Roll Angle 3.21°
Roll Angle difference: 0.35° (more in rear)
Average roll angle: 3.04°

B. Modern High Front Travel/Low Roll Set-up
LF -3.000" ... RF -2.000" ... Difference 1.000" ... Front Roll Angle 1.15°
LR -0.750" ... RR +0.500" ... Difference 1.250" ... Rear Roll Angle 1.48°
Roll Angle difference: 0.33° (more in rear)
Average roll angle: 1.32°

There is a LOT to learn from these notes about these two different strategies.

The major key differences to note are:
• With the conventional set-up, look at how much more the car rolls, measured in inches.
• On the conventional set-up, notice how both the inside front & rear suspensions "extend" & lift.
• In the modern set-up, see how both sides of the front suspension compress. The inside corner does not lift, it just doesn't compress as far.
• In a modern set-up, only one corner ... the inside rear ... actually extends while
cornering & braking. Everything else compresses.
• On a conventional setup, note how the rear suspension travels slightly more than the
front ... and a lot more than the modern set-up.
• On a modern low roll set-up, note that the front suspension travels significantly more
than the rear suspension.

The similarities are:
• Both set-ups have a higher rear roll angle compared to the front roll angle.
• Both set-ups achieve a similar difference in front to rear roll angles.

Regardless of suspension strategy chosen ... low roll, high roll, tweener ... you need the
rear roll angle slightly greater than the front roll angle.

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Tuning Roll Angle & Diagonal Roll

When designing a suspension or tuning a race car, I utilize calculations known
as:
• Total Roll Stiffness (TRS) measured in pounds per degree of roll angle
• Front Lateral Load Distribution (FLLD) expressed in a percentage of TRS
• Rear Lateral Load Distribution (RLLD) expressed in a percentage of TRS

I know some tuners utilize spring frequency and/or front & rear roll couple numbers. These numbers don't provide us as clear of a picture as TRS, FLLD & RLLD. Total Roll Stiffness (TRS) calculations provide us with an easily quantifiable measurement of roll resistance in the suspension. It takes into account spring rates & sway bar rates.

FLLD/RLLD calculations use this number ... plus front & rear track widths, front to rear weight bias, CG height, front & rear roll center locations ... to provide us the percentage of "Total Roll Stiffness" in the front suspension (FLLD %) and the rear suspension (RLLD %).

Don't get lost in the terms. TRS is simply a way to measure & refer to the stiffness of the spring & sway bar combination. FLLD is simply how much of that stiffness is in the front suspension. RLLD is how much of that stiffness is in the rear.
If we have an example car with springs & sway bars with 3000# of TRS, that means it takes 3000# of force to roll it one degree. If the car also weighed 3000# of total track ready weight it would take approximately 1.0g to roll the car to an average roll angle of 1.0°. By average roll angle, I mean averaging the front & rear roll angles. You still want more roll angle in the rear. In this same example, 1.5g would roll the car to about a 1.5° average roll angle.

If this same 3000# car only had 1500# of TRS
• 1.0g would roll the car to an average roll angle of 2.0°
• 1.5g would roll the car to about a 3.0° average roll angle.

If we had a 6000# truck with 1500# of TRS
• 1.0g would roll the car to an average roll angle of 4.0°
• 1.5g would roll the car to about a 6.0° average roll angle. *Assuming it could achieve
1.5g

Does this help clarify what Total Roll Stiffness (TRS) is?
Now let's move on to splitting this roll stiffness into the front end & rear end. One might incorrectly assume that FLLD 50% & RLLD 50% would mean the car will roll evenly ... front & rear ... on track. This is incorrect because it doesn't take into account front to rear weight bias ... or weight transfer under braking.

Before we go any further, embrace two major things about weight.
1. The end of the car with more weight bias will naturally roll more.
2. Weight transfer to the front, while braking, will make the front roll more when cornering.

So, a car with a 53% front weight bias (and 47% rear weight bias) is going to roll more in the front, unless we stiffen the front suspension to account for the additional weight we have to control. This is accounted for in the formulas. But weight transfer to the front while braking is not. So you need to. I typically target 5% higher FLLD% than front weight bias. With this 5% higher FLLD% ... the car will still achieve a slightly higher rear roll angle ... which is the goal.

If the car truly has a 50/50 weight bias, my target FLLD% would be 55%, and obviously the RLLD percentage would be 45% to make the total add up to 100%. If I have a car with 53% front weight bias, my target FLLD% would be 58%. Simply making the FLLD% higher is not the goal or your desired direction of tuning. This 5% stiffer front suspension, is only a baseline set-up to account for the weight/load transfer from braking hard into the corner. You will need to tune from there.

As a tuning guide only ... because there are exceptions ... TYPICALLY:
a. Decreasing the front roll resistance (FLLD) ... increases the front roll angle ... and loosens the car during corner entry & middle.
b. Increasing the rear roll resistance (RLLD) ... decreases the rear roll angle ... and loosens the car during corner entry & middle.
c. Increasing the front roll resistance (FLLD) ... decreases the front roll angle ... and tightens the car during corner entry & middle.
d. Decreasing the rear roll resistance (RLLD) ... increases the rear roll angle ... and tightens the car during corner entry & middle.

Within reasonable differences making the front track width wider than the rear ... or the
rear wider than the front can be a practical tuning tool. Making the front track width wider than
the rear = tightens the car ... too much makes it push. Wider rear track width than front track
width = frees the car ... too much makes it loose.

What happens if you space the tires in or out ... changing track width ... changes the load distribution on tires. For conversation sake, if we had a car we decided to tune on ... by adjusting track width ... the results would be:
A. Moving the front tires inward, narrowing the front track width, will load the outside front tire more & the inside rear tire less when cornering ... freeing or loosening the car up to a degree.
B. Moving the front tires outward, widening the front track width, will load the outside front tire less & the inside rear tire more when cornering ... tightening the car up to a degree.
C. Moving the rear tires inward, narrowing the rear track width, will load the outside rear tire more & the inside front tire less when cornering ... tightening the car up to a degree.
D. Moving the rear tires outward, widening the rear track width, will load the outside rear tire less & the inside front tire more when cornering ... freeing or loosening the car up to a degree.

Obviously ... how much effect these track width tuning changes make is dependent upon the degree of change. An average sport/club driver would for sure notice a 1/2" spacer reduction or addition. Highly developed drivers that I have worked with could tell if we changed
it 1/16".

*Note: Adding spacers to the front hubs, increases the Scrub Radius. So, when I can use ... either adjustable LCA's ... or simply replace the LCA's for the track width I want ... that is how I prefer to do it, versus adding wheel spacers to the front. I have used wheel spacers in the front many, many times. It's just not my preferred method. Sometimes class rules dictate the decision. Spacers are a no brainer tool for the rear.

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Ideally, you want a wide track width AND zero Scrub Radius. When you're in a situation
where you have to give up one for the other, the rule of thumb is ...

Slower tracks with tighter corners ... give up track width for lower Scrub Radius.
Faster tracks with bigger corners ... accept higher Scrub Radius to achieve wider track width.

Make sense?

Apr 13, 2026, 06:19 PM

Part 4 of 4

How do you increase the TRS number and reduce the car's average roll angle with setup?
• Bigger sway bars ... or stiffer springs ... or some combination of both.
• Remember, the suspension has to travel, so lean towards one of the proven strategies of low travel/high roll or high travel/low roll.

How do you tune the roll angles individually & therefore the diagonal roll angle?
* This is assuming you have achieved the desired target "Average Roll Angle" and just need to balance the car for neutral handling.

If the car is tight/pushy ... decrease the FLLD % (& increase the RLLD%) ... to loosen the car up:
• Decrease front spring rates
• Increase rear spring rates
• Decrease front sway bar rate*
• Increase rear sway bar rate*
• Narrow the front track width
• Widen the rear track width
• Lower the front roll center
• Raise the rear roll center
• Raise the front CG
• Lower the rear CG
• Combination of these tuning items

If the car is free/loose ... then do the opposite of the above to increase the FLLD % & decrease the RLLD% ... to tighten the car up.

These are not the only tuning options to tune the handling of the car on cornering. Far from it. These are the simple items to tune the front to rear percentage of roll resistance in your suspension to balance your car for neutral handling. Shock valving is a fine tuning tool also, but doesn't show up in TRS, FLLD or RLLD calculations.

There are many real world exceptions to the tuning guidelines above. Some of the biggies are:
• Anything that reduces the contact patch or effectiveness of the front tires
• Anything that reduces the working/loading of the inside front tire.
• Anytime you get a tuning setting outside of its happy window.
• In the advanced racing suspensions I deal with, there are also things we do with
extreme shock valving, bump stops, sway bars & roll centers, that the typical formulas
don't take into account.

*Examples of exceptions:
• If you increase the Diagonal Roll ... with the goal of turning better ... and don't adjust & correct the dynamic camber of the front tires to maintain the optimum contact patches, you may not free the car up. In fact, you may make it tighter/pushy midcorner.
• If you decrease the front sway bar rate too far ... in an attempt to achieve more Diagonal Roll onto the outside front tire ... and this change reduces grip of the inside front tire ... it will not turn better. In fact it may push.
• If you go too stiff with the rear sway bar rate ... outside its happy tuning window ... it can keep the inside rear tire "too engaged".
• If you go too stiff with the rear spring rate ... outside its happy tuning window ... it can keep the inside rear tire "too engaged".
• Stiffer rear springs or sway bars need a lower roll center keep the inside rear tire disengaging, to the proper degree, when turning.
• Tuning a race/track car is all about the total combination, not one change.

Rookie tuners often get themselves confused because the change they made ... that the book said will work ... didn't work or even made it worse. They don't understand why it didn't work ... because they didn't think about what else that change affected ... and "the book" didn't cover it. Veterans learn from lots of real world track time, testing and racing. I have seem lots of "experts" with book knowledge think all tuning changes are absolute. Tuners, Crew Chiefs & Race Engineers with real world experience ... who have been there & done that ... and know better

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Amount of front end travel combined with the degree of roll angle:
While the ideal degree of front-to-rear roll angle difference may be similar in the two suspension strategies ... the front & rear roll resistance (FLLD %) required to achieve this angle is not necessarily the same. Conventional low travel/high roll set-ups do not transfer as much load to the front ... so there is less load to control with roll resistance.

Modern high travel/low roll suspensions transfer more load to the front end ... so there is more load to control with roll resistance. There is not a huge difference, but a difference nonetheless.

So, a car with a 53% front weight bias and a FLLD of 58%
• May be on the free/loose side with a modern high travel/low set-up ... and need a FLLD of 58.5-59.5%
• May be on the tight/pushy side with a conventional low travel/high roll set-up ... and need a FLLD of 56.5-57.5%
• This is if all other factors were the same ... and they rarely are from car to car.

FLLD % is a great guideline, but only a guideline. We can not go to ten different cars (all with a 53% front weight) ... and simply say 58% is the optimum FLLD % for every one of those ten cars. There are too many other factors that affect the car's turning ability to say there is an optimum FLLD % that will absolutely work for every car.

Here are examples of other factors:
• If the front steering geometry is not optimum ... and the tires are not achieving optimum contact patch ... the car is going to be tight/pushy.
• If the car has a lot of jacking effect from a high caster & high scrub radius, that car will be looser.
• If the car has little jacking effect from low caster & low scrub radius, that car will be tighter.
• If the car is not aero balanced ... with too little rear downforce ... that car will be looser.
• If the car is not aero balanced ... with too much rear downforce ... that car will be tighter.
• If we run bump stops with super soft springs ... and allow the car to travel past its optimum point ... that car will be loose.
• If we run bump stops and shim them to reduce the travel too much ... that car will tight/pushy.

If you have these issues, you can band-aid the problem with different track widths, spring & sway bar rates to get the car neutral, but it's won't be as fast as the car is truly capable.

Reminder: FLLD % is calculated utilizing the front & rear spring rates, sway bar rates,
track widths, weight bias, CG height & roll center locations.

FLLD % can tell us when we should look at other areas for our handling problems. Using the same example of a car with 53% front weight and a baseline FLLD of 58% ... if we find we need a far different FLLD percentage to get the car to handle neutral ... we probably have problems somewhere other than spring & sway bar rate. Make sense?

If that car is pushing with a 58% FLLD ... and you fix it with a softer front sway bar that gets the FLLD to 52% ... The push is probably being caused by something else, like:
• Less than optimum front geometry & less than optimum contact patch under dynamic
conditions.
• Too little jacking effect.
• Too much rear downforce
• Etc, etc.

I did not go into every possible problem here, but I hope everyone has embraced that FLLD % is a good tool for working out your front & rear spring rates, sway bar rates, track widths, weight bias, CG height & roll center locations for a total handling package.

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Summary:

For Optimum Corner Handling ... You Need to Disengage the Inside Rear Tire ... To a Degree Diagonal Roll is the method to achieve this, utilizing the g-forces of braking & cornering.

The keys to controlling the amount of Diagonal Roll & therefore the degree the
inside rear tire disengages:
• Degree of jacking effect ... from KPI, caster & scrub radius ... and rear spring rate.
• Roll angle difference ... front to rear ... achieved with suspension tuning
• Remember the amount of front end travel combined with the degree of roll angle plays a role.
• Utilize FLLD percentages as a tuning guideline

I want to open up conversation for any questions or thoughts on diagonal roll, jacking effect, TRS, FLLD, etc.[/b]

Apr 13, 2026, 06:22 PM

Quik-Tune Adjustments

The following may sound like an advertisement for my Quik-Tune suspension components ... and it probably is to a degree. But this is my belief. Face it ... if tuning adjustments are hard to do or take too long ... they usually don't get made & we suffer through a less than optimum handling race car. RSRT Quik-Tune features are the solution!

I was a winning crew chief for almost 40 years. I know tuning on race cars can be time consuming, So I engineered all the RSRT track & race cars to be quicker, easier & predictable to tune, so you can dial in your car at any track, under any conditions.

For the rear roll center, RSRT Watts link or panhard bar, you can tune your rear roll center height, with a 1/2" ratchet, to balance the handling of your race car in seconds, not minutes. You simply open the trunk & adjust the rear roll center up for more front grip, or down for more rear grip. With our Quik-Tune Watts link, put a 1/2" ratchet in the center adjuster cone & turn it right to lower the roll center or left to raise it. You have 6" of range at the tip of your fingers.

With our Quik-Tune double adjustable panhard bar, you have two adjuster cones. 4" range on the driver/chassis side & 6" range on the passenger/axle side. In addition to the option of adjusting both evenly, if you need more rear grip & less front grip turning one way & more front grip & less rear grip turning the other way, you can do that with panhard bar adjustments.

If you need more rear grip on left hand corners, adjust the driver side lower. If you need more rear grip on right hand corners, adjust the passenger side lower. If you need more front grip on left hand corners, adjust the driver side higher. If you need more front grip on right hand corners, adjust the passenger side higher. Combinations of these also work well.

Using the same 1/2" ratchet, you can adjust ride heights, corner weights & cross weights on RSRT's Quik-Tune jack screw coil-over shock mounts. Plus, this does NOT affect the bump stop gap or travel range of the shocks.

Adjusting the ride heights, front or rear heights individually & dialing in the optimum crossweight on the scales ... or at the track ... is much quicker & easier with Jack-Screw Adjusters on each coil-over. No more getting down in the suspension to loosen the lock collar on the coil-over ... turning it with a spanner wrench ... busting some knuckles during the process ... and retightening the lock collar ... multiple times until you get it right!

Simply loosen the 1-1/8" jam nut on the jack screw, put a 1/2" ratchet in the top of the jack screw adjuster, then turn it right to raise the car or load that corner more. Turn it left to lower the car or load that corner less.

Raising or lowering the whole car, or just the front or rear, has never been quicker or easier. Same with adjusting the crossweight to increase total grip on corners of one direction, while simultaneously reducing total grip on opposite corners.

Need more front & rear grip on left hand corners & less on right hand corners? Adjust the left front & right rear jack screws down to load the tires more & adjust the right front & left rear THE EXACT SAME AMOUNT, but up to load the tires less. Ride heights will not change. Need the opposite effect? Do the opposite.

Use the 1/2" Ratchet with a 3/4" Socket & 3/4" wrench to tune the rear sway bar for Mid-corner tuning. Need more mid-corner grip, simply soften the rear sway bar. Need the Car to free up & turn better in the middle? Adjust the rear sway bar stiffer. Remember you can split holes to really fine tune the change.
You can use the same 1/2" Ratchet with a 3/4" socket & 3/4" wrench on the front sway bar as well. Track conditions change? You can move 1 link 1 hole & make a measurable change (about 100#) to overall handling.

Need more front grip? Soften the bar. Need more rear grip? Stiffen the front bar. Car rolling too much & getting loose in the high speed corners? Stiffen the front bar. Car not rolling enough & pushing in the slow corners? Soften the bar.

Adjusting the Quik-Tune RSRT 3-link anti-squat is also quick & easy. Through the passenger door, put the 1/2" ratchet in the adjuster cone & turn it right to increase the anti-quat (more rear grip on exit, but less on entry) or left to reduce it (more rear grip on entry, but less on exit). You have 4" of range of the front top link pivot point to find the optimum compromise.

Have our Quik-Tune Decoupled 3-Link? No compromises. You're tuning the Accel link for corner exit only, since the Decel link works separately to create amazing rear grip on corner entry (under braking). Need more rear grip on exit? Turn the adjuster cone to the right to increase anti-squat. Got too much rear grip on corner exit ... and the car is pushing to the outside of the track under throttle? Turn the adjuster cone to the left to decrease anti-squat.

Adjusting the rear track width is as quick as unbolting the two rear tires. You can add wheel spacers to widen the rear track width, shifting grip from the rear tires to the front tires for better turning. Or, you remove wheel spacers to narrow the track width shifting grip from the front tires to the rear tires for better acceleration & grip upon corner turn in. Our strategy is to start with 1/2" spacers to match thew front track width. Then you can narrow or widen up to 1".

Adjusting the shock valving is the go-to tuning tool when you need to improve handling at driving "transitions" like initial throttle pick up, initial brake application, initial steering turn-in, etc.
All RSRT race shocks are easily adjustable with a dial, pin wheel or knob. Singles are adjustable on the low speed rebound side, which is the number one tuning tool. Doubles are adjustable on rebound & compression. Typically, adding rebound increases grip on that end.

Tuning the bump stop shims (aka packers) is quick & easy. Need more rear grip on corner entry, under braking? Add equal shims on both sides. Need the car to turn better on corner entry? Remove equal shims on both sides. Got a tricky track with one direction of corners giving you grief? Add or remove bump stop shims on just one corner.

Adjusting steering ratio is not possible with most spindles. With RSRT spindles, you can dial in the steering speed (ratio) you want for personal preference, or track size. Simply swap the steering slugs shorter for quicker steering, longer for slower steering, in minutes. Changing the steering arm slugs can be done in 2 minutes if you're prepared.

As track conditions change throughout the event, or when you run different tracks, having quick & easy tuning methods is crucial. There are many proven methods, if you build them into your car from the start. I'll outline many here:

Quik-Tune Watts or Panhard Bar:
*Adjusting up shifts grip to the front tires & down shifts grip to rear tires

Quik-Tune 3-Link Top Link (or Accel Link on Decoupled 3-Links):
*Adjusting the front down provides more rear grip at throttle roll on & up provides more rear grip later on long, sweeping corner exits

Quik-Tune Coil-Over Adjusters:
*Adjusting the LF & RR up & the RF & LR down equal amounts tightens the car on RH corners & frees the car on LH corners without affecting the ride height of the car.
*Adjusting the RF & LR up & the LF & RR down equal amounts tightens the car on LH corners & frees the car on RH corners. Perfect for courses with a majority of turns one direction & a minority of turns the other direction

Cockpit Coil-Over Wedge Adjuster:
*Achieves the same goal as above, except can be adjusted by driver on track, to dial in handling for that session. With the hydraulic weight jacker set in the middle, the driver can shift grip to help either RH or LH corners with a knob turn on the console

Bump Stops on Front Shocks:
*Increasing shims loads the rear tires harder increasing rear grip on corner entry under braking & reducing shims loads the fronts more increasing front grip on entry
*Adding a shim to only one side (LF for example) adds dynamic wedge on corner entry & tightens the car on RH corner entry & frees the car on LH corner entry

Spring Rubbers:
*Creating our neutral setup at the shop with moderate rate spring rubbers already in the rear coil-over springs provides us a quick track tuning tool
*Changing to stiffer rate spring rubbers in the rear shifts grip to the front tires & softer spring rate rubbers (or removed altogether) shifts grip to the rear tires

Basic Shock Tuning:
*Adjust the shock valving when the handling issue only happens on TRANSITION from or to throttle, braking and/or steering input.
*Stiffening the front shock compression and/or rear shock rebound tightens the car on corner entry & at brake release. Softening the front compression and/or rear rebound frees the car on entry & at brake release.
*Softer front rebound and/or stiffer rear rebound tightens the exit & vice versa.

Rear Wheel Spacers:
*When we have an extra inch width in the rear wheel tubs, we build the floater rear end (5/8" studs) 1" narrower on each side & setup our neutral baseline to run 1/2" wheel spacers. At the track, decreasing or removing the spacers shifts grip to the rear tires & increasing the spacer thicknesses (1" Max) shifts grip to the front tires.

Quik-Tune Sway Bars:
*Adjusting the links to make the arms longer makes the bar softer, shifts grip to that end of the car & shorter makes the bar stiffer, shifting grip to the other end of the car
*For fine tuning you can adjust just one side for half the change

Brake Bias Cockpit Cable Adjuster:
*Adjusting the brake bias towards the front brakes tightens up the race car under hard braking & shifting bias to the rears frees up the car under hard braking.

Apr 13, 2026, 06:29 PM

Ron Sutton Quick Tuning Guide:
Tuning for balance is easy, when you embrace 5 keys.

1. Get the inner, outer & middle tire temps on all four tires every run, or as often as is feasible. Record them in your note book. (We offer free templates that Ron Sutton uses.)
2. Measure all four tire pressures after every run, or as often as is feasible. Record them in your note book. Determine your car's baseline & record it.
3. Measure all four shock travels every run, or as often as is feasible. Record them in your note book. Determine your car's baseline & record it. Rear travel shows roll & front shows dive.
4. Measure all four rotor temps every run, or as often as is feasible. Record them in your note book. Determine your car's baseline & record it. Now let's tune!
5. Some track tuning you do will be to correct the dive and/or roll amounts to hit your targets. The rest of tuning you do will be to increase or decrease rear tire grip to achieve balance.

If the car is loose on entry & exit ...
* Do the rear tire temps show high or low temps in the center? If yes, adjust rear pressures.
* Is the car rolling over too far? If yes stiffen the front sway bar.
* Is the car not rolling enough? If yes, soften the rear sway bar.
* Car still not rolling enough? Lower the rear roll center and/or narrow the rear track width.

If the car is loose on corner entry only ...
* Do the rear tire temps show high or low temps in the center? If yes, adjust rear pressures.
* Is the front end dive traveling too far? If you run bump stops, simply add shims until your dive travel is on target. If you do not run bump stops, stiffening the front shock compression will help a little. If you need to reduce travel more, change to the next stiffer front springs.
* Is the car rolling too far? If yes stiffen the front sway bar.
* Is the car not rolling enough? 3 options: Lower the rear roll center, narrow the rear track and/or soften the rear sway bar.
* If the dive, roll & tire temps are good, stiffen the rebound on rear shocks for a little help. (You can go too far on rear rebound & actually make the car looser, so pay attention to this.)
* If the loose entry condition is not fixable with the tuning above, you may have too much anti-squat or too much rear brake bias. Check the brake temp bias to know which to fix.

If the car is loose on corner exit only ...
* If the rear tire temps are hotter than normal, either roll the throttle on slower or tune the car.
* Does the tire spin start instantly? Crack the throttle easier & roll the throttle on slower.
* Is the car rolling over too far? If yes stiffen the front sway bar.
* Is the car not rolling over enough? If yes, soften the rear sway bar.
* Roll angles good? Soften rebound on front shocks & stiffen rebound on rear shocks.
* Still need more grip on exit? If yes, increase the anti-squat in your rear suspension.

If the car is loose in the "roll through" section when you're off brake & gas ...
* Thank your lucky stars. Don't tune on the car. Simply carry more corner speed (by braking softer or shorter) up to the point the car starts getting tight/pushy in the middle.

If the car is tight or pushing the entire corner ...
* Do the front tire temps show high or low temps in the center? If yes, adjust front pressures.
* Check the toe-out. We know you set it at the shop. Trust us, recheck it first, before tuning.
* Is the car not rolling over enough? If yes, soften the front sway bar.
* Is the car rolling over too far? If yes stiffen the rear sway bar.
* Is the car still rolling too far? Raise the rear roll center and/or widen the rear track width.

If the car is tight or pushing on corner entry only ...
* Is the front end diving enough? If no, look at tire temps. Cooler front tire temps vs rear usually mean the driver is NOT going into the corner as deep & braking as hard as needed.
If this is the case, tune on the driver, not the car. If the driving is good ... read on:
* Do the rear tire temps show high or low temps in the center? If yes, adjust the tire pressures. * Is the front end dive traveling too little? If you run bump stops, simply remove shims until your dive travel is on target. If you are not compressing the bump stops, run softer springs.
* If you do not run bump stops, softening the front shock compression valving will help a little. If you need to increase travel more, change to the next softer front springs.
* Is the car rolling over too far? 3 options: Raise the rear roll center, widen the track width and/or stiffen the rear sway bar.
* Is the car not rolling enough? If yes, soften the front sway bar.
* If the dive, roll & tire temps are good, soften the rebound on rear shocks for a little help.
* If the tight or pushy entry condition is not fixable with the tuning above, you may have too much front brake bias. Check the brake temp bias to know for sure.

If the car is tight or pushing on corner exit only ...
* If the front tire temps hotter than normal, straighten out your corner exit line or tune the car.
* Does the tight or pushing condition start instantly? Stiffen the rebound on front shocks.
* Is the car rolling over too far? If yes stiffen the rear sway bar.
* Is the car not rolling over enough? If yes, soften the front sway bar.
* If the dive, roll & tire temps are good, stiffen rebound on front shocks & soften rebound on rear shocks for a small gain.
* Still need less grip on exit? If yes, decrease your anti-squat in rear suspension.

If the car is tight or pushing in the "roll through" section when you're off brake & gas ...
* Welcome to the most common ... and hardest to fix ... handling problem in motorsports. If you can give up a little rear grip on corner entry or exit ... use those tuning strategies mentioned earlier.

This will help you to reduce the tight/push condition in the roll through. When you have fine-tuned all you can ... and have the car balance on the edge of free on entry & exit ... and the car is still tight in the middle ... the Driver simply needs to carry less roll through speed (by braking a little harder or longer) just up to the point the car turns well in this zone.

Measure & record tire temps, psi, brake temps & shock travel & you have the key info to tune!

Apr 13, 2026, 06:34 PM

Shock rebound adjustability takes priority over compression adjustability. Why?

Simple. On compression the spring rate & shock compression valving are working together. On rebound the spring rate & rebound vavling are opposing each other.

On compression the shock valving is providing some hydraulic resistance that adds to the spring rate, slowing down the rate of compression on that corner of the car. For conversation sake, let's say we have two cars, one with 900# front springs expecting to dive 1 inch under hard braking. The second car with 300# springs expecting to dive 3 inches under hard braking. If our front shock compression valing provides 50-100# hydraulic resistance, all we were doing is slowing down the rate of compression of that 900# or 300# spring.

But on rebound, the shock valving is the ONLY thing slowing the lift (rebound) of that corner of the car. Some racers describe it as the shock & spring are fighting each other in rebound. Again, for example sake, let's utilize those same two cars. Both have 900# of stored spring energy in full dive under hard braking ... just waiting for the driver to release the brakes.

Once the driver releases the brakes that 900# of stored energy from the compressed spring (on each side) wants to pop the front end of the car up instantly. 50-100# hydraulic resistance wouldn't do much to slow that spring "boing!" LOL We need much more rebound resistance & the ability to adjust the rebound resistance.

Now you should realize WHY the rebound valving of the shocks ... and having a wide adjustable range on the rebound valving ... is so important. The shock's rebound valving is the only thing controlling the spring rate coming back up. This is why shock rebound adjustability takes priority over compression adjustability.

Being able to adjust the compression valving over a wide range is valuable, but not as valuable as the rebound adjustability. For this reason, double adjustable shocks are not twice as good for tuning ... as long as our single adjustable shocks are rebound adjustable. Another key thing to know is increasing the rebound valving is how we create more grip. The front rebound valving rate is how we create more front tire grip mid-corner ... the key to carrying more corner speed.

Shock rebound adjustability takes priority over compression adjustability in the rear as well. Increasing the rear rebound valving rate is how we create more rear tire grip on corner exit, under throttle. This additional rebound keeps the rear tires loaded longer on exit. Increased rear rebound valving rate also increases rear tire grip on corner entry under braking. It holds the rear of the car down longer ... keeping load on the rear tires ... even though the front end has dived under braking.

But if we get "greedy" & dial in too much rear rebound valving rate, the rear tires will literally lift with the chassis/body as the driver brakes hard into a corner. This unloads the rear tires, making the car loose on entry. So the goal is to run all the rear rebound valving you can, without being loose on entry.

The old school belief the driver needs to always be on the gas or brake, and never coast, is no longer true. It used to be true, but modern shock technology changed that. See driving line below. Green is throttle on. Red is brake on. Blue is neither. The race car is rolling (or coasting). This is called the "Roll Through Zone."

Visualize this, it's corner entry on a fast course. The driver brakes hard & the front end dives a certain amount ... then, while still braking, the driver initiates steering into the corner. Ideally this racer has dialed in their camber, caster, toe & Ackerman settings to create optimum front tire contact patches while in dive, roll & turning. If they are advanced, they've worked out their roll center to load the tires optimally too. Plus, the front CG is lower (by the amount of dive), less air is flowing under the car & more air is flowing over the hood creating downforce.

But when the driver steps off the brakes, deep into the corner, the stored energy from the compressed front springs pushes the front end up in milliseconds. You instantly have less contact patch on both tires, the roll center is no longer optimum, the front CG is higher & more air is flowing under the car again. The car instantly goes into a push condition (understeer).

For this reason, old school racers learned to keep brake pressure on, all the way to the point where they needed to get back on the throttle. That's where the phrase "you need to always be on the gas or brake, and never coast" came from. BUT ... this longer braking zone is scrubbing off lots of speed, killing lap time.

Modern shock technology has cured this. Winning Pro Racers learned they could modify the shock bleed circuit to keep the front end "tied down" for a short, controlled time. The rest of the time, the shocks work normal.

This tie-down allows the driver to get off the brakes and the front end stays down where the tire contact patches are optimum, the roll center is optimum, the front CG is lower & the airflow is still going over the car, not under it. This allows the driver to get completely off the brakes earlier, creating a "roll thru zone", before throttle pick up without pushing (understeer)!

Back in the day this "roll thru zone" did not exist unless you were going so slow it didn't matter, which the fast racers called coasting. Now, with the front end tied down for a short period of time, before the throttle pick up point, the driver can carry greater mid-corner speed.

The longer the tie-down time, the more speed we can carry through the corner. Ron Sutton has literally seen 3-5 mph mid-corner speed increases from racers switching to the new tie down shock technology. But, factors like how long the corner is & how rough the track surface is, play a role in how long we can tie the front end down.

If we get "greedy" & dial in too much front tie down valving rate, the front tires will literally skip over the asphalt undulations in the corner, creating a push (understeer) towards the outside of the corner.

Your goal at each track is to find the limit of tie down you can run, without creating a push condition.
Ron Sutton's Front Tie-Down Guide:
1. 200-400# (0.25 – 0.50 sec) Works Best for Autocross
2. 400-600# (0.50 - 0.90 sec) Works Best for Rough Road Courses
3. 600-800# (0.90 - 1.30 sec) Works Best for Average Road Courses
4. 800-1000# (1.30 - 1.70 Sec) Works Best for Smooth Road Courses
5. 1000-1200# (1.70 – 2.10 Sec) Works Best for Super Smooth Road Courses

Shock Tuning Tips

Make these tuning changes in this order:
1. Stiffen the bleed adjuster on the front shocks to help keep the nose pinned down in the roll through zone. Go stiffer until the car gets loose on corner exit ... or starts skipping the front tires & pushing mid corner. When you experience either of these ... soften the bleed back up ... until these conditions stop.
2. Stiffen the rebound valving on the front shocks to slow the rise of the nose on corner exit acceleration. Go stiffer until the car gets loose on corner exit ... or starts skipping the front tires & pushing mid corner. When you experience either of these ... soften the bleed back up ... until these conditions stop.
3. Stiffen the rebound valving on the rear shocks to help keep the rear planted all the way out of the corner on exit. Go stiffer until the car gets loose on corner entry ... or starts hopping the rear tires in any part of the corner. When you experience either of these ... soften the bleed back up ... until these conditions stop.
4. Stiffen the bleed adjuster on the rear shocks to help keep the rear planted all the way out of the corner on exit. Go stiffer until the car gets loose on corner entry ... or starts hopping the rear tires in any part of the corner. When you experience either of these ... soften the bleed back up ... until these conditions stop.
5. If the car is loose on corner entry upon initial dive under braking ... AKA landing on the bump stops ... you can adjust the front shock compression valving stiffer until it stops. Do not stiffen the compression adjuster anymore than it needs, as this adds hysteresis into the suspension. Chose another suspension tuning option first if it is available.
6. If the car is tight/pushy on corner entry upon initial turn-in ... you can adjust the rear shock compression valving stiffer until it turns betters. Do not stiffen the compression adjuster anymore than it needs, as this adds hysteresis into the suspension. Chose another suspension tuning option first if it is available.

Steps #1 & #2 will help the car turn better "mid-corner" when you're "rolling or coasting" with no brakes or throttle. We call this critical area the "Roll Through Zone." Steps #3 & #4 will provide more grip on corner exit. Pay attention to when it affects grip on entry & middle.

The middle of the corner is the highest priority. If the car won't turn well in the middle, the entry & exit are inconsequential. Don't accept any tuning change that hurts the "Roll Through Zone" handling & speed.

Do these in this order & take lots of notes. You won't be able to remember all the details accurately. I don't know any top race teams that don't use "run sheets" to keep track of changes, results, etc. Keep a report of each run, with all 4 shock settings, the handling results on corner entry (braking & turning), Middle (coast) & Exit (throttle roll on & steering unwind) ... and the differences from the previous run. You'll learn firsthand what changes do.

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Then, go back through the same process, but fine tune with 2 clicks, then 1 click until you find the best balance. Experiment with a "little here & a little there" strategy. Experiment with a "less here & more there" strategy.

Once you're "happy" with the handling ... this is your baseline set-up. Write it down & place it in a vault. Whenever you find yourself "out-to-lunch" with tuning ... go back to your baseline. If after more events & testing, you improve on your shock settings, make that your new baseline. Write it down & place it in a vault. Whenever you find yourself "out-to-lunch" with tuning ... go back to your baseline.

FYI: If you adjust any of shocks too stiff on compression or rebound, and the shock(s) prevent the suspension from following the undulations of the track surface, you lose grip on that end of the car, without gaining grip on the other end of the car. This is one tuning change that doesn't shift grip. It simply reduces grip at the wheels where the shock valving is too stiff.

Fine Tuning for Day, Track, Conditions, Etc.

Loose Entry:
• Stiffen the bleed and/or rebound valving on the rears. You "may" gain grip back on entry. If it gets better, go until the car gets loose again on corner entry & back up ... or until you run out of adjustment. If it gets worse ... stop & back up to the baseline setting ... and move on to the next step.
• If still loose ... stiffen the bleed and/or rebound valving on the rears. You "may" gain grip back on entry. If it gets better, go until the car gets loose again on corner entry & back up ... or until you run out of adjustment. If it gets worse ... stop & back up to the baseline setting ... and move on to the next step.

If still loose ...
• If you think the front end is traveling too far (not too fast) ... add equal thickness bump stop shims to each front shock.
• Reduce rear braking force with adjustable proportioning valve.
• Try braking softer & longer.
• As a last resort of shock tuning, stiffen compression on front shocks until the car grips up on entry. Don't go any stiffer than needed, as this may tighten up the roll through zone & it adds hysteresis into the suspension.
• If still loose on entry, the cure may require a stiffer front springs or sway bar rate.

Tight/Pushy Entry:
• If you are not already full soft on the front shock compression valving ... then soften compression on front shocks until the car frees up on entry. Don't go any softer than needed, as this will make the car loose on entry.
• If you think the front end is not traveling far enough ... remove equal thickness bump stop shims to each front shock.
• If still tight/pushy ... soften the bleed and/or rebound valving on the rears. Go until the car gets loose again on corner entry turning & back up ... or until you run out of adjustment.
• If still tight/pushy ... stiffen the compression on the rears. Go until the car gets loose again on corner entry turning & back up ... or until you run out of adjustment. Don't go any stiffer than needed, as this may loosen up the grip on corner exit & it adds hysteresis into the suspension.
• If still tight/pushy on entry, induce rear braking force with adjustable proportioning valve.
• If still tight/pushy on entry, try braking harder.
• If still tight/pushy on entry, the cure will require a softer front spring rate.

Loose during "roll through zone" only:
• Pinch yourself, because you're dreaming. Or, you have over slowed the race car.
• Are you sure the car isn't loose, or pushing, on entry causing the car to get loose in roll through zone only?
• This is great news ... brake softer, but the same length & increase the roll through zone speed until the car comes back to neutral handling. If it gets tight, you may need to brake slightly harder to decrease roll through zone speed & cure it.
• Ok, if it is really loose in roll through zone only ... soften up the bleed valving on the front shocks.

Tight/Pushy during "roll through zone" only:
• If you think the front end is not down on the track far enough ... remove equal thickness bump stop shims to each front shock.
• Stiffen bleed on the front shocks until the car frees up in the roll through zone.
• If still tight/pushy in the roll through zone, stiffen the rebound valving on the front shocks until the car frees up in the roll through zone.
• If still tight/pushy in the roll through zone, soften the rebound valving on the rear shocks until the car frees up in the roll through zone.
• If still tight/pushy during "roll through zone" only, brake harder, but the same length & decrease the roll through zone speed until the car comes back to neutral handling.
• If still tight/pushy in the roll through zone, the cure will require more than shock & braking adjustment.

Loose Exit:
• Stiffen the rebound valving on the rears. Go until the car gets tight on exit ... or loose on corner entry ...and back up ... or go until you run out of adjustment.
• If still needs more grip ... stiffen the bleed valving on the rears. Go until the car gets tight on exit ... or loose on corner entry ... or you experience rear wheel hop anywhere ... and back up ... or go until you run out of adjustment.
• If still loose, soften the rebound valving on front shocks until the car grips up on exit ... or gets tight in the roll through zone. Don't go any softer than needed, as this will tighten up the roll through zone.
• Do not soften the bleed valving on the front shocks UNLESS the roll through zone is awesome AND the tires spin the instant you touch the throttle.
• If still loose on exit, experiment rolling the throttle on later or slower.
• If still loose on exit, the cure will require more than a shock or driving adjustment.

Tight/Pushy Exit:
• If any adjustment range left, stiffen the bleed valving on the front shocks. Go until the car gets good on exit ... or go until you run out of adjustment.
• If still tight/pushy on exit ... and if any adjustment range left ... stiffen the rebound valving on the front shocks. Go until the car gets good on exit ... or go until you run out of adjustment.
• If still tight/pushy on exit, soften the bleed valving on the rears. Go until the car gets good on exit ... or until it hurts the entry ... or until you run out of adjustment.
• If still tight/pushy on exit, soften the rebound on the rears. Go until the car gets good on exit ... or until it hurts the entry ... or until you run out of adjustment.
• If still tight/pushy on exit, experiment rolling the throttle on later or slower.
• If still tight/pushy on exit, the cure will require more than a shock or driving adjustment.

[/b]

Apr 13, 2026, 06:36 PM

Tuning the Track Car with Tire Temps

Tire temperatures are an excellent guide for tuning race cars in general, and specifically the front end geometry. Tire pyrometers are a simple tool to get accurate results ... if used correctly. On my race teams, we use either the Longacre or Intercomp digital pyrometer with memory.

You stick the probe into the tire tread (inside first, center next, outside last) ... listen for the "beep" telling you it has the temp ... push the button to "capture" the # ... and move onto the next spot ... all the way around the car. It stores & shows all 12 numbers (4 tires x 3 spots) in one display. We then write the numbers down in what we call a "run sheet" of the car's tuning notebook.

What? You don't have run sheets? No notebook? If you're going to get fast & win events ... better get a notebook & run sheets. Because if you can "remember" all the info from your testing ... you are NOT testing enough and/or not measuring enough key details. I'll post a version of a run sheet on here down the road, so you can download them, customize & print them out.

The digital pyrometers we use with memory, save a lot of valuable time ... when the tire is cooling off fast ... because you don't have to write as you go. But they are a little spendy. The versions we use, also have a 4-car lap timer built in them, so the crew can time our car & up to 3 competitors at the same time. It stores all the info for putting into the run sheets after the session.

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It is expensive, but will make you go faster than any other $400 you'll spend. Go HERE.
For a little less expensive version, with no stop watch, go HERE.
* I like & recommend Pegasus Auto Racing Supplies as a good source for small parts, tools, etc. they are road racers & know their shit.

Do not use an infrared temp gun. It's not ok. The misinformation IS WORSE than no information. The reason is simple. The surface of the tire cools fast ... and equalizes. Surface temps will not show you accurate differences across the tread or from tire to tire. Use a probe type pyrometer. End of story.

Being consistent is critical, or numbers varying from run to run will make you crazier than you already are. Slicks are easy ... we measure 1" in the inside ... dead center & 1" in from the outside. Note: Some slicks have relatively thin surfaces, so stick the sharp probe into the rubber deep at a 45 degree angle, so you don't pop the tire.

On treaded or grooved tires, the 1" number may put the probe in a funky spot on the tire blocks or close to a groove. My rule of thumb is to put the probe into the center of the outside tread blocks or runners, hopefully in the ½" to 1" range for the edges of the tire. With thicker street tires you can go straight in with the probe. Go deep.

Be consistent with your depth & placement of the probe into the tire tread ... and always go in the same order ... as quickly as you can before the tires cool too much ... and you'll have the most valuable data available for tuning.

I'll map out how we do tire monitoring and we can go from there.

First, I decide if we're running air or nitrogen. I always prefer nitrogen if it is practical to use, just because there is much less pressure change as heat builds up in the tires. If it is my first time running a tire, I reach out to the manufacturer & get a suggested operating pressure window for the tires & start right in the middle ... and test.

I'm looking for the optimum hot operating tire pressure. In doing so, we're always
going to:
1. Set the tire pressure before we go out.
2. Check & note the tire temps as soon as the car rolls into the pits.
3. Check & note the tire pressures right after that.
4. Reset the "go out" tire pressures with what we learned to achieve optimum hot temps &
pressures.

When the car comes back into the pits, I have a guy with a memory tire pyrometer take all 12 readings ASAP. He puts the probe deep into the rubber ... about 1" from the inside edge of the tire ... then the middle ... and then about 1" from the outside edge of the tire ... and captures these numbers for review.

Most guys know if the temps are low in the middle, the tire pressure is too low. If the temp is high in the middle the pressure is too high. Adjust the "go out" tire pressures until the car comes back with correct middle temps. Pay attention & note the tire pressure gain each session until you have a handle on this.

What's common ... especially if the front geometry is off ... is to see one edge of the tire hotter than the other edge. Obviously you have an issue you need to correct, but for sake of your track day, you need to optimize the tire the best you can. If the tire is hotter on one edge ... split the difference ... and that is your target center temperature. So if the front tires read 145°-130°-129° ... the center is too cool and the tire needs more pressure until the tire comes back reading around 145°-137°-129°. This isn't optimum. Far from it. You need to correct the geometry and get the temps closer. How close is based on your performance standards. I get mine within 2°.

Once the tire temps guide you to the optimum "roll into the pits" tire temps & pressures, that will be your target every time. For sake of discussion, let's say the optimum tire pressures come back at 32 psi front & rear. Your "go out" pressure will depend on two factors ... how much do the tire pressures increase in a session and how cool or warm are the tires before your track session.

When you first get to the track, and the tires are ambient temperature ... "cold" ... you will need to start with lower pressures, because the tire pressures will grow the largest amount on the first run. Again, just for discussion, let's say you find you need to start at 25 psi front & rear on "cold" tires ... and after your first session the tires come back in at 32 psi. For the next session, your "go out" pressures with "warm" tires will need to be below 32 & above 25 ... unless the car sits so long the tires get "cold" again. You may find the tires only typically grow 4 degrees from "warm" to "hot" so your go out pressures
would be 28.

Only experience can tell you how much the tire pressures will grow from cold-to-hot and from warm-to-hot. But once you have these numbers you can plan accordingly. There are many factors that affect this though. If the day is particularly hot ... the tires will grow more pressure, so you start lower. The reverse is true for cold days with little to no sunshine on the asphalt.

You may find your front & rear tires grow pressure at different rates. Pressure gain is all about heat & work. So if the rears grow more pressure than the fronts, you probably have a loose condition on entry, middle or exit ... over working those rear tires. The driver needs to give feedback as to whether they're spinning the tires on exit or sliding on entry and/or middle. Conversely, higher pressure growth in the front tires signal a car that is tight/pushy ... or potentially being overdriven on corner entry.

Another factor in tire temps is brake heat. If the driver is abusing the brakes, the tires will be hotter. If the brake bias is correct, this will affect the front tires more, as the front brakes run hotter.

Through experience, you want to develop a "typical" pressure growth from cold-to-hot tires so you know how to set your tires before your first session. And you want to develop a "typical" pressure growth from warm-to-hot tires so you know how to set your tires before your subsequent sessions. And you want to be aware of the factors that may affect tire pressure growth ... like braking issues, being over driven, track temps, etc ... so you can adjust your "go out" pressures to still achieve the optimum hot pressures.

If you care about having a good track day, and want to have a good handling car and work on your driving ... you need tire & brake rotor temps. These two will help you learn more, run better, be safer and improve more than anything else you do. Always check tire temps (with a probe pyrometer) & pressures when you roll back in. Check all 4 rotor temps with an infrared pyrometer. And always write your notes in a book.

From this info you can tell a ton about how the driver & car are doing. Plus, you can spot problems before they bite you. The brake rotor temps can tell you if you're braking too much, too little or just right. they can tell you if you have a correct brake bias ... or too much front or rear braking. The tire temps & pressures can tell you if you're over driving or under driving the entries, middles and/or exits of the corners. They can tell you if you have a balanced or unbalanced car. They can tell you if geometry issues.

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Let's run through some examples ... assuming we have a track or road race car on a road course running equal size Hoosier R7 slicks front & rear ... with an optimum tire temp around 190 degrees. I'll start with the basics & progress. Here is what the tire temps tell us.

Across the face of the tread
LF 190 180 190 RF 190 180 190
LR 180 190 180 RR 180 190 180
Conclusion: Front tires are under inflated & rear tires are over inflated.

Difference left to right
LF 180 180 180 RF 190 190 190
LR 180 180 180 RR 190 190 190
Conclusion: Either the track has more LH turns than RH, the car has more right side weight bias, the car's suspension is set up for a higher Roll Angle on LH turns & lower Roll Angle on RH turns or some combination of these causes.

Difference front to back – Part 1
LF 210 210 210 RF 210 210 210
LR 190 190 190 RR 190 190 190
Conclusion: Car is tight and/or pushing, the driver is over driving the car on corner entry or both.

Difference front to back – Part 2
LF 170 170 170 RF 170 170 170
LR 220 220 220 RR 220 220 220
Conclusion: Car is loose, the driver is over powering the tires on corner exit or both.

Difference opposing corners
LF 180 180 180 RF 190 190 190
LR 190 190 190 RR 180 180 180
Conclusion: Car has cross weight in the suspension set-up causing it to be tighter on LH corners & more free on RH corners.

Difference on edges – Part 1
LF 200 190 180 RF 180 190 210
LR 190 190 190 RR 190 190 190
Conclusion: Front wheels & tires do NOT have enough Dynamic Camber. (Do not confuse this with Static Camber or Camber Gain.)

Difference on edges – Part 2
LF 185 190 195 RF 195 190 185
LR 190 190 190 RR 190 190 190
Conclusion: Wheels & tires have too much Static Camber.

What if one tire is too cool
LF 190 190 190 RF 190 190 190
LR 180 180 180 RR 190 190 190
Conclusion: Either due to track or driver, the car is exiting some RH corners easier or gentler. Cross weight may be slightly off as well.

What if one tire is too hot
LF 205 205 205 RF 190 190 190
LR 190 190 190 RR 190 190 190
Conclusion: Either due to track or driver, the car is entering some RH corners deeper & more aggressively. Or you have a brake caliper dragging on that corner.

What if all the tires are too cool
LF 160 160 160 RF 160 160 160
LR 160 160 160 RR 160 160 160
Conclusion: Either the driver is under driving the car, the car has too small of a Roll Angle, the track surface is cold ... or a combination of these issues.

What if all the tires are too hot
LF 210 210 210 RF 210 210 210
LR 210 210 210 RR 210 210 210
Conclusion: Either the driver is over driving the car, the car has too large of a Roll Angle, the track surface is super hot ... or a combination of these issues.

There is a lot more to this. These were just some samples. With experience, you can learn how to read tire temps, differences & even the face of the tire & know what the car is doing. Remember harder compound tires have lower operating temperatures than my samples. And as tires age, the rubber hardens, so they will run cooler too ... because they're "dead" ... meaning the rubber has hardened.

Having & using a tire durometer is smart too. (like THIS) It will let you know the condition of tires & if you have a "bad" tire. We ran 6 USAC Midgets and set-up them up as identically as is possible with humans. Spring rates within 3#, shock valving within 5#, ride heights within .010" ... you get the point. When we roll all of them out at the track on new rubber & one of them handles differently than the rest ... we check the tires with a durometer before anything else.

Sure enough ... if a front tire is harder than is normally should be ... or a rear tire is softer than it should be ... that car pushes. Vice versa too. You can tune & tune & tune, but all you're doing to putting a band-aid on the problem and you're going to have bad days as long as that tire is on the car. We simply change the tire. Problem solved & sanity returns to what you're doing.

A lot of people ask me what are acceptable split numbers ... either across the tread ... or from side to side. "Acceptable" varies with the person ... like saying it's cold. My wife says it cold when its 60 degrees. Having lived in parts of the country where it gets in the teens or occasionally single digits ... 60 is a pleasant spring day ... to me.

An acceptable tire temp variance is different with each tuner. I know a lot of racers have a larger "acceptable" window than me & are ok with ... 5-10-15 degrees differences. I'm not looking for "acceptable" ... unless that is the new term for "optimum." Optimum is 2 degrees or less across the face of the tire. Any more than that, and my race crew has tools out.

As with all guidelines, there are exceptions. I've seen series with tires so hard the only way to get heat in them was to run them on the edges or over inflate them & run them on the center. But for most racing tires & most low tread wear performance street tires ... my number is 2 degrees. If I'm road racing, I allow no more the same 2 degrees from side to side. If it's more, we're tuning on it to get more grip & speed.

When I tell you I have often achieved tire temps within that same 2 degree window ... comparing side to side ... when I was oval track racing stock cars ... after you stop calling me a liar ... realize we ran very low Roll Angle ... and we can tune some things "special" because we're only turning left.

Heck, we have had the left front & left rear tires HOTTER than the right side tires on an oval track. That's not optimum. I just don't want you to think the outside tires always have to be hotter & "accept" that.

Maximizing front tire grip is the key factor to corner speed & lap times. Front tire grip is my highest priority. Because adjusting the rear grip to match the front grip ... for a balanced "neutral" handling car ... is relatively easy.

Said another way, If the front tires can only maintain 52.3 mph in corner X ... then the car is only going to go 52.3 mph through corner X. Anything you do to adjust rear grip isn't going to make the car going faster than 52.3 mph through corner X. You could make the car loose ... or push ... and go slower than 52.3 mph ... but not faster. The only time the rear grip is the limiting factor is if your setup or tuning is not working, or we have a high rear weight bias race car.

If we tune on the front geometry & raise the front tires grip so it would carry 52.7 mph through corner X ... and then we tune the rear grip to balance that ... we raised our corner speed .4 mph in corner X ... and probably most of the other corners too.

If a car I'm working on has more than 2 degrees temp split across the tire ... or difference side to side ... we're getting tools out.

When you go to the track for your initial test & tune, remember these key points:
• Balance the high speed corner handling with aero downforce ... specifically rear wing adjustment.
• Balance the low & mid speed corner handling with suspension tuning ... specifically rear Roll Center, shock valving, spring & sway bar rates.
• If the front end geometry is not optimum, corner speeds will be down in the tighter corners & the tire temps will tell you why. Tune accordingly.

In my experience the priority for tuning the front suspension geometry is the tighter, low & mid speed corners ... as long as the car is not loose in the high speed corners. On any given road course these different corners will have different needs. You may find (with DAQ) you've got 21° of steering in one corner and 9.5° in another. Obviously those steering differences are going to produce very different dynamic Camber numbers ... as they should.

A great test & tune tool is a skid pad. (It's a good driver training tool too.) If you have access to a safe, controlled, flat, measured parking lot skid pad ... it is killer for testing geometry & tire temps. I suggest you set the radius to match your most challenging corners. You can go either direction (clockwise or counter) but pick just one & stick with it for the day. For our conversation, let's say clockwise.

Use a tire pyrometer with a probe (no infrared) to measure the temps in the center of the tread ... and both inside & outside of the tread. Stick probe in rubber DEEP about 3/4"-1" in from the edge of the tread on each side & in the middle. Writes notes every time.

Tuning tips:
• If the car ends up rolling more than projected, you'll want to increase the Caster to keep both tires at optimum angles for full contact patches. If the car ends up rolling less than projected, you'll want to decrease the Caster to keep both tires at optimum angles for full contact patches. See examples 1 & 2.
• When need Camber to help responsiveness at turn in but it hinders the inside tire achieving optimum contact patch for turning grip through the corner ... so don't get greedy with Camber. See examples 3 & 4.
• Increasing the Caster & decreasing the Camber increases the "split" or difference in Dynamic Camber between the outside & inside tires.
Decreasing the Caster & increasing the Camber decreases the "split" or difference in Dynamic Camber between the outside & inside tires. See
examples 5, 5A, 6 & 6A.

For a clockwise skidpad , if BOTH the outside of the LF tire & the inside of the RF tire are hotter than the rest of the tire, reduce the Caster. If they're BOTH cooler, increase the Caster.
Examples:
#1 - If LF reads: 141-135-130 ... & RF reads: 161-155-150 = Car is rolling less than projected ... so reduce Caster
#2 - If LF reads: 130-135-141 ... & RF reads: 150-155-161 = Car is rolling more than projected ... so increase Caster

If the inside of BOTH tires are hotter than the rest of the tire, reduce the Camber. If the insides are cooler, increase the Camber.
Examples:
#3 - If LF reads: 130-135-141 ... & RF reads: 161-155-150 = reduce Camber
#4 - If LF reads: 141-135-130 ... & RF reads: 150-155-161 = increase Camber
When one tire is optimum & the other is not ... adjust the Dynamic Camber split.

Examples:
#5 - If LF reads: 130-135-141 ... & RF reads: 161-160-159 = Needs more Dynamic Camber "split" ... so increase the Caster & decrease the Camber.
0r #5A - LF reads: 141-140-139 ... & RF reads: 161-155-150 = Needs more Dynamic Camber "split" ... so increase the Caster & decrease the Camber.
#6 - If LF reads: 141-135-130 ... & RF reads: 161-160-159 = Needs less Dynamic Camber "split" ... so decrease the Caster & increase the Camber.
0r #6A - LF reads: 141-140-139 ... & RF reads: 150-155-161 = Needs less Dynamic Camber "split" ... so decrease the Caster & increase the Camber.

Ultimately, you want the temps across the tires to be within 2° when driven at 102%.

Apr 13, 2026, 06:38 PM

Exceptions to the Rule:
There are some tuning items that do NOT SHIFT grip. Earlier I mentioned if you adjust any of shocks too stiff on compression or rebound, and the shock(s) prevent the suspension from following the undulations of the track surface, you lose grip on that end of the car, without gaining grip on the other end of the car. This is a tuning change that doesn't shift grip. It simply reduces grip at the wheels where the shock valving is too stiff.

Suspension bind is a "condition" not tuning. But it can & has led many crew chiefs astray. Suspension bind stops the suspension from working. Similar to the shock being way too stiff. Where we have suspension bind, we lose grip & it doesn't shift that lost grip anywhere.

Rear Roll Steer is another. When you introduce Rear Roll Steer, you are affecting the rear grip only. Yes, you can make the car tight/pushy or free/loose with Rear Roll Steer. But you're only affecting the grip at the rear tires, not the grip of the front tires. This is different than having the shocks too stiff where the only outcome is less grip.

With Rear Roll Steer, you can run positive rear steer to help the car turn better. This reduces rear tire grip when cornering. Or, you can run counter (negative) rear steer. This increases rear grip when cornering.

Apr 13, 2026, 06:41 PM

Achieving optimum handling & consistency

The goal is to achieve optimum handling for each corner ... and consistency in the handling & feel of the race car. In an ideal world, we would find the optimum Diagonal Roll and achieve it every corner.

The challenges are ...
• Corners vary in several ways: entry speeds, radius, banking, cornering speeds, grip, etc.
• So the braking needs vary from corner to corner.
• Then you have human drivers who can not be perfectly consistent with their turn in points, braking points, degree of turning, lines chosen, degree of braking & length of braking.
• Braking & turning are the factors that cause diagonal roll.

In most suspensions without travel limiters, if you get the suspension set to be very forgiving it will not be as fast as it can be. If you get it "top of the leader board" fast, it is somewhat less forgiving. This is why drivers who can drive at the limit more consistently win races.

Here are some very real world what-ifs that vary from lap to lap:
• What if the driver brakes harder than ideal ... and the car rolls diagonally too much? Car gets loose on entry.
• What if the driver brakes softer than ideal ... and the car rolls diagonally too little? Car is typically fine on entry but pushes in the middle.
• What if the driver brakes too early ... and the car rolls diagonally too little? Car is typically fine on entry but pushes in the middle.
• What if the driver brakes too late ... and the car rolls diagonally too much? Car gets loose on entry.
• What if the driver turns in harder than ideal ... and the car rolls diagonally too much? Car gets loose on entry.
• What if the driver turns in softer than ideal ... and the car rolls diagonally too little? Car is typically fine on entry but pushes in the middle.
• What if the driver combines some of these inconsistencies? We take an otherwise good handling car & turn it into an ugly handling car.
• What if the driver varies these from corner-to-corner ... lap-to-lap? We get inconsistent lap times ... and probably inconsistent feedback from the driver as to what the car needs.

See where the challenges are?
Of course, we need to improve the driver's skills. We need to improve his or her mental awareness of their driving actions, on track, in the thick of things. We need to improve their self-discipline to do the right things for each corner, consistently lap-after-lap. Seat time, driver coaching, seat time, good books, seat time, driving schools, seat time & observing other drivers ... along with more seat time ... can all help the driver to "improve" ... but they'll never stop being human. That is what makes this fun, challenging & interesting.

But what if we could make the car more consistent?
Hmmm. How?
Well, through testing, we can find the optimum Diagonal Roll angle for a car & track. What some don't know, is the optimum Diagonal Roll angle for the fastest corner is not a ton different than the slowest corner. IT IS DIFFERENT ... but not as much as you may think. So, what if we had one strategy to achieve a similar Diagonal Roll angle every time ... and another strategy to vary that Diagonal Roll angle the correct direction & amount for faster & slower corners?

We can ... but we need to control how far the front end suspension travels ... and to a degree, we need to control roll angle too. This is where racing bump stops come into play. These are not to be confused with the "safety bumpers" on many shocks, which are merely there to protect the shock body in the case the shock bottoms out.

Racing bump stops are designed to control suspension travel in racing applications. They are engineered with progressive spring rates that allow us to pick & choose how far they compress & how fast. Combine the right rate of bump stop with quantifiable shims ... and you have the ability to control EXACTLY how far the outside front suspension compresses.

The right bump stop package controls our diagonal roll!

It works like this ...
• If we determine the optimum compression travel for the outside front suspension is X.xx" ... and that not only loads the outside front tire the correct amount ... but the Diagonal Roll angle achieved also disengages the inside rear tire to the optimum degree ... then we shim the front bump stops to limit travel to that exact travel #.
• If the previous non-limited set-up "usually" got to the optimum travel, we will typically decrease the front spring to a degree, to ensure, even with somewhat less braking force, we still get to the optimum X.xx" travel # ... and optimum Diagonal Roll angle.
• Now ... unless the driver is way out to lunch ... the front end will get in "the optimum travel window" in every corner.

But we need a strategy to decrease the Diagonal Roll angle for faster corners ... to a small degree ... and to increase the Diagonal Roll angle for slower corners ... to a small degree. We have two tools at our disposal.
• The primary tool is the "jacking effect" when turning the steering wheel. This de-wedges the suspension to some degree. How much jacking effect we have is controlled by KPI, caster, scrub radius ... and most importantly ... the degree we turn the steering wheel.
• So, in tighter, slower corners, where we need a higher Diagonal Roll angle ... you turn the wheel more ... and get it ... through increased jacking effect.
• In the faster, more sweeping corners, where we need a lower Diagonal Roll angle ... you turn the wheel less ... and get decreased jacking effect.

Cool? Yes, but we're not done. Sometimes the degree of jacking effect in the car is too much or too little. Here is my approach ...
• I have found from experience we put the fastest package on track when we minimize scrub radius and optimize the KPI & caster for optimum tire contact on both front tires when the car is in full dive & roll angle. In other words "dynamically".
• I "usually" do not tune caster or give up scrub radius for more jacking effect. There are exceptions.
• I usually change the rate of bump stops in the front suspension to effect the net front roll angle.
• If I need a higher Diagonal Roll angle when turned harder in tight corners ... I put a softer rate of bump stop in the front suspension.
• If I need a lower Diagonal Roll angle when turned harder in tight corners ... I put a stiffer rate of bump stop in the front suspension.

When I do tune on the geometry for more or less jacking effect, I always do so with a combination of caster & camber change. For example, if the car is good almost everywhere ... but tight/pushy in the tightest corners ... if I have emptied my tool box of other tuning tools & the car still needs a little more jacking effect, I'll do it.

Here is how:
Increasing the caster ... increases the "dynamic camber" split between the two front tires. If the geometry was optimum for the outside front tire ... and if we only increased caster ... the outside front tire would suffer with less grip. That's not helping us get the car turning better. So we need to reduce camber too ... to get the outside tire back to the optimum "dynamic camber" angle it was before. In doing so, the inside front tire now has more "dynamic camber" and therefore more jacking effect. Remember, simply adding caster without subtracting camber can make the car tight/pushy.

Conclusion:
• You can utilize bump stops (& slightly softer springs) to get the car in the Diagonal Roll angle "happy window."
• The bump stop softness/stiffness and jacking effect help optimize the Diagonal Roll angle for different radius/speed corners.
• You can fine tune the Diagonal Roll angle with bump stop softness/stiffness and jacking effect.

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Bump Stops are often clouded in mystery.

In reality, there are a simple tuning tool for corner entry under braking. They are simply an additional, progressive spring that engages only when you want more spring rate to load the tire & stop the front end travel.

If you have the right setup, they gently stop the front end dive at your target travel amount. Every Time. This loads the front tires more than non-bump stopped setups AND keeps the rear tires loaded. That consistency grip is confidence inspiring, while allowing the driver to learn, experiment & even make errors ... without costly crashes.

Bump stops increase the wheel rate & load the front tires more than regular setups & keeps the rear tires loaded too. That consistent grip is confidence inspiring, while allowing the driver to learn the track, experiment with deeper braking zones & even make errors, without crashes.

Tuning? If the car is loose on entry under braking & turn in, add more shims. If the car is tight or pushy under braking & turn in, remove shims. Yes, it is that easy if you have the right bump stop rate curve. Ron can provide you with the rate charts for all the air & polyurethane bump stops we use, as well as set you up with the optimum starting place for air or poly bumps.

FYI: There are 4 common types of bump stops .... cellular foam, polyurethane, small coil spring & air spring. We don't use cellular foam because they lose rate too quickly with use. We don't use small coil springs because they do not have the progressive rate we want. Poly bumps work well, are least expensive, but do need to be replaced. Air bumps are tunable for any progressive rate we need. So, we don't need to stock a range of polys. But they cost more.

On rough tracks we run softer rate bump stops. On smoother tracks, we can run stiffer rate bump stops to gain more grip & quicker lap times. Pro racers looking for every ounce of grip & lap time will run very high rate bump stops, as long as the track is smooth enough.

Another cool tuning strategy for road courses is being able to tune the grip on corner entry of left hand & right hand corners separately. If the car is loose on entry of left hand corners, simply add a shim to the RF. If the car is tight on entry of left hand corners, simply remove a shim in the RF. Just do the opposite on righthand corners to make ALL the corners optimum!

Final note: Bump stops are one of the few things that increase grip on all 4 corners. The added spring rate at the front wheel loads the front tires more (more grip) while also keeping more load on & grip in the rear tires. In fact, we need to make sure we're not too aggressive with bump stop rates or we'll wear the tires out sooner.