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  1. #1
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    Default Overall Handling & Tuning for Track Performance

    Skip this part if you know me or simply don’t care.

    A little bit about me:
    I’ve been racing for 35 years in 80+ classes of racing, most professionally, including drag, road course, karts & oval track. From low powered Formula Fords & F2000 cars to Mountain Motor drag racing … Midgets, Sprint Cars, Super Modifieds … to GT road race cars, Modifieds, Late Models & NASCAR Stock Cars. I’ve had the good fortune to work with & learn from winning teams & smart people in SCCA, USAC, SRL, NHRA, IHRA, IMSA, Indy Lights, Indycar, Grand Am & NASCAR.

    Most of my modern experience is in road racing & oval track, as I haven’t been to a drag race since 1987. My operation has had 3 names, but settled on Ron Sutton’s Winner’s Circle about 20+ years ago. It was a statement to our commitment to winning. But in 2006, we joked about changing it to Ron Sutton’s Third Place Circle when we had nine 3rds & only one win … then we designed & built new cars in the off season & got back to winning. Today, my business that offers parts, complete cars, technical services & car/track consulting is named Ron Sutton Race Technology.

    Many of you know what “married up” means. I did. My sweet wife Kim is very supportive of my crazy career & involved a lot, but doesn’t work in it on a day-to-day basis. When I look back, the numbers are a little overwhelming. We’ve built 64 tube chassis pro style cars & 140+ sportsman cars for clients. We’ve had a chassis shop, parts store, track stores & engine R&D over the years. I’ve owned 79 race cars myself … including 9 full time race teams until 2012. Most years we were at the track 3-4 days a week, 40+ weeks out of the year. How I stay married is completely a mystery, and I know I’m fortunate.

    After I broke my back racing aero karts at Sears Point in 1991 I realized it’s the friends & relationships I have in the motorsports that I value most. That didn’t change how hard we worked … it just changed my viewpoint about relationships & teamwork. Frankly we started winning more races as I learned how to build better teams & developed more friendships with competitors & resources within the sport.

    I live & breathe competition, and I believe winning comes from doing your homework, testing, working hard, testing more, learning from books, classes & mentors … and testing more. I’m not the smartest guy at the track, but when he goes home I’m still there testing & learning. I figure I have 2500+ days of track testing under my belt. As a driver, owner, crew chief or driver coach I have 498 personal wins & 22 championships. My clients' wins total in the thousands.

    We closed my 9 team operation & parts business at the end of 2012. The economy being so bad for so long dried up too much sponsorship for us to continue racing as we did. When Dale Earnhardt Jr. had 13 races unsponsored in 2013, you know it’s tough. I sold all the parts, equipment, race cars & rigs and took some time off to relax ... whatever that is. I enjoyed a little slower pace, writing a series of tuning books and having fun building my new ’57 Chevy PT/Street Fighter, which is the prototype for my new Warrior cars. It's on hold now as I am busy helping so many clients build new cars or improve their current car. I’m really enjoying meeting a lot of good people in this part of the car sport. I already knew Mike Maier for several years, as he raced Midgets in USAC too. For those of you who know him only from AutoX, Mike won races in USAC Midgets too. He’s a hardcore racer & a winner.

    I’m not an engineer. I’ve worked for them & with them … and had several work for me … but we’re from different planets. One of my friends said, “Ron is a race car designer that did not go to engineering school, so he speaks car guy.” I’m a veteran car guy committed to staying on the leading edge of performance & racing technology. I like to think I’m pretty knowledgeable in my areas of expertise … but I learn every week, if not every day ... and there is a ton I don’t know about street cars, style, paint & body, upholstery, car accessories, etc, etc, etc.

    I know I’m tired of talking about me … so let's get to the topic.



    --------------------------------------------------------------------------------------------------

    This Forum Thread is for discussing & learning about “Overall Handling & Tuning for Track Performance.”

    For a thread focused on: Front Suspension & Steering Geometry for Track Performance ... click HERE.
    For a thread focused on: Rear Suspension & Geometry for Track Performance ... click HERE.
    For a thread focused on: Measuring & Modifying Your Front Suspension Geometry ... click HERE.
    For a thread focused on: Designing Aerodynamics for Track Performance ... click HERE.
    For a thread focused on: Safety for Pro-Touring Track Cars ... click HERE.
    For a thread focused on: Brake Selection ... click HERE.


    I promise to post advice only when I have significant knowledge & experience on the topic. 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. I’m writing some books and want car guys to understand them. When you’re really not clear on something I said … please bring it up & help me improve.

    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 & I think it 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.

    .
    Last edited by Ron Sutton; 12-30-2014 at 06:56 AM.
    Feel free to chime in or ask technical questions. I am here to help where I can.

    Ron Sutton

    Ron Sutton Race Technology
    Your One Stop, Turn & Go Fast, Car Building Resource Center for Autocross, Track, Road Racing & Triple Duty Pro-Touring Cars

    Check out our 400 Page Car Building Catalog HERE

    Features: Suspension, Chassis, Cages, Brakes, Rear Ends, Engines, Transmisssions, Aero & Much, Much More!


  2. #2
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    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.


    ----------------------------------------------------------------------------------------------

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

    Shorthand Acronyms
    IF = Inside Front Tire
    IR = Inside Rear Tire
    OF = Outside Front Tire
    OR = 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.

    ARB = Anti-Roll Bar
    FLLD = Front Lateral Load Distribution
    RLLD = Rear Lateral Load Distribution
    TRS = Total Roll Stiffness
    TAR = is those black round things the car rolls on. (Sorry, couldn’t resist)
    WT = Weight Transfer

    CG = Center of Gravity
    RC = Roll Center
    IC = Instant Center
    RA = Roll Angle

    ----------------------------------------------------------------------------------------------

    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.

    Total Roll Stiffness is the mathematical calculation of the “roll resistance” built into the car with springs, ARB’s, track width & roll centers. Stiffer springs, bigger ARBs, 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 Angle: is the amount the car “rolls” on its roll axis (side-to-side) in cornering, usually expressed in degrees.
    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.

    Dive = is the front suspension compressing under braking & cornering forces.
    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
    Roll = Side to side body rotation … aka body roll.
    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.

    Track width = is center to center of the tread.
    Tread width = is outside to outside of the tread. (Not sidewall to sidewall)
    Tire width = is outside to outside of the sidewalls.
    A lot of people get these confused & our conversations get sidelined.

    Spring rate = pounds of linear force to compress the spring 1”.
    Spring force = total amount of force (weight and/or weight transfer) on the spring.

    Anti-Roll Bar, ARB, Sway Bar & Anti-Sway Bar … all mean the same thing. Kind of like “slim chance” & “fat chance” ...
    ARB Rate = Pounds of torsional force to twist the ARB 1 inch at the link mount.

    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.

    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.

    .
    Feel free to chime in or ask technical questions. I am here to help where I can.

    Ron Sutton

    Ron Sutton Race Technology
    Your One Stop, Turn & Go Fast, Car Building Resource Center for Autocross, Track, Road Racing & Triple Duty Pro-Touring Cars

    Check out our 400 Page Car Building Catalog HERE

    Features: Suspension, Chassis, Cages, Brakes, Rear Ends, Engines, Transmisssions, Aero & Much, Much More!

  3. #3
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    20 CRITICAL TUNING CONCEPTS:

    1. What you do WITH & TO the TIRES ... are the key to performance. Contact patch is the highest priority.

    2. Geometry design, settings & changes should be to improve how the tires contact the road dynamically.

    3. The design structure of every component affects how well that component handles the forces inflicted upon it.

    4. After the car is built, tires are selected & the geometry is optimum … most chassis fine tuning is to control the degree of weight transfer to achieve the traction goal.

    5. Force (weight & weight transfer) applied to a tire adds grip to that tire. With the exception of aerodynamics, weight transfer from tire(s) to tire(s) is the primary force we have to work with.

    6. Anti-Roll Bars primarily control how far the front or rear suspension (and therefore chassis) “rolls” under force, and only secondarily influences the rate of roll. Stiffer bars reduce roll angle, keeping the car flatter, working the inside tires better.

    7. 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.

    8. Springs, shocks & anti-roll bars need to work together “as a team” … with the springs’ primary role of controlling dive & rise, anti-roll bars’ primary role of controlling roll & shocks primarily role controlling the rate of both. They all affect each other, but choose the right tool for the job & you create a harmonious team.

    9. A production based car, 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.

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

    11.
    Tuning to allow a suspension corner … to compress quicker or farther … provides more force & therefore more grip to that tire … up to the limits of the tire. Tuning to allow a suspension corner … to extend/rebound quicker or farther … provides more force & therefore more grip to the opposite corner’s tire … up to the limits of the tire.

    12. Softer springs allow more compression travel & therefore more force onto the tire … for MORE GRIP. Stiffer springs reduce compression travel & therefore lessen force onto the tire … for LESS GRIP.

    13.
    Optimum 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.

    14. 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.

    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. Tuning is NOT linear 2 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 car can be pushy because it has too little roll angle in the front & is not properly working the outside front tire. A car can be pushy because it has too much roll angle in the front & is not properly working the inside front tire.

    18. The car’s Center of Gravity acts as a lever on the Roll Center … separately front & rear. Higher CG’s and/or lower RC’s increases roll angle. Lower CG’s and/or higher RC’s decrease roll angle. Getting the front & rear of the car to roll similar is desired. Getting them to roll the same is not, because …

    19. Goal: To have optimum grip on all tires and disengage the inside rear tire (to a degree) to turn well … then re-engage 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 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.

    20. Don’t forget the role & affects the engine, gears, brakes, driver & track conditions each have on handling.

    .
    Feel free to chime in or ask technical questions. I am here to help where I can.

    Ron Sutton

    Ron Sutton Race Technology
    Your One Stop, Turn & Go Fast, Car Building Resource Center for Autocross, Track, Road Racing & Triple Duty Pro-Touring Cars

    Check out our 400 Page Car Building Catalog HERE

    Features: Suspension, Chassis, Cages, Brakes, Rear Ends, Engines, Transmisssions, Aero & Much, Much More!

  4. #4
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    All handling cars need to travel the suspension to work.

    The car can’t run flat … it needs to travel … so it’s either got to Roll or Pitch … that’s the primary difference in the two tuning concepts I’ll outline. There are two common strategies that work. One relies more on the roll angle & the other on pitch angle.

    Roll Angle vs Pitch Angle
    • A competition car should not pitch AND roll a LOT … it would be dangerous & undrivable
    • A competition car should not pitch AND roll a LITTLE … running too flat would make it just skate on the road surface.
    • A competition car can pitch a lot & roll a little … OR … pitch a little & roll a lot

    You need to pick a path … so here is what they look like.

    -------------------------------------------------------------------------------------------------------

    Conventional:
    • Stiff front springs & soft rear springs
    • Small, soft rate sway bars front & rear (if any in rear)
    • Higher Roll Angle when cornering
    • Less Pitch Angle Change in dive under braking

    Old School – Let it Roll
    • High Roll Angle (3° +/-)
    • Front suspension doesn’t compress much on corner entry. (1” +/-)
    • Work the outside tires for grip & work the inside tires less so it will turn.

    Drawbacks:
    • Too much roll angle overworks the outside tires in corners & under works the inside tires.
    • The tires heat up quicker & go away quicker, providing a better short run set-up.
    • After tires “come in” the car is “knife edgy” to drive.
    • Very line sensitive … drivers say, “can’t drive it just anywhere” … meaning it handles poorly out of its optimum groove.
    • As the track grip increases & the car rolls more … these problems magnify.
    • When it rolls a lot & you brake hard, the inside rear tire has no grip. So to prevent from being loose on entry you must run stiffer front springs.
    • The stiffer front springs make the car tight/pushy in the middle … requiring the driver to brake more and run slower corner speeds.

    -------------------------------------------------------------------------------------------------------

    Modern:
    • Soft front springs & stiff rear springs
    • Big, stiff sway bar in front & small sway bar in rear
    • Known as SS/BB … soft spring/big bar … if no bump stop or coil bind is utilized
    • Same concept used in conjunction with travel stops: Bump Stops or Coil Bind
    • Lower Roll Angle when cornering
    • More Pitch Angle Change in dive under braking

    New School – Get the nose on the ground & run the car flatter
    • Roll angle is minimal, controlled primarily by the sway bar in front & stiffer rear suspension. (1° +/-)
    • Front suspension travels a LOT in dive (compress) to put maximum load & grip on front tires. (3” +)
    • Load the outside tires only slightly more than inside corners for optimum 4 tire corner grip.

    Disadvantages:

    • Even when optimized … it still can not be driven as deep on corner entry as a conventional set up.
    • When racing door-to-door in a field of race cars running a mixture of set-ups, the SS/BB set-up is susceptible to dive bomb passes.

    Advantages:
    • Flatter Roll Angle works the tires more evenly.
    • The tires heat up slower & last longer … making a better long run set-up as the tires are “good” way longer.
    • Less line sensitive … drivers say, “I can drive it just anywhere” … meaning any line on the track.
    • As the track grip increases … the advantages show more.
    • The soft spring/high travel front end puts creates maximum grip on front tires for highest cornering speeds.
    • Will produce faster cornering speeds & quicker lap times over conventional set-up, all other things being optimum.

    ----------------------------------------------------------------------------------------------------------------

    The two successful types of suspensions ... conventional stiff front spring/small sway bar - low travel/high roll ... and modern soft front spring/big sway bar - high travel/low roll ... have been used successfully at all types of tracks from AutoX to Laguna to Daytona. They are just different strategies to travel the suspension. The conventional relies on more roll, & the modern relies on more front suspension travel.

    There is a third successful strategy ... which is to run a set-up somewhere in-between. Often referred to as 'tweener set-ups or moderate set-ups, because they utilize moderate front end travel (2" +/-) & moderate roll angle (2° +/-).

    I used the term "have been used successfully" ... because the conventional strategy hasn't been used in the top levels of Indy, F1, Grand Am, NASCAR, ALMS, etc. for many, many years ... on any track ... big or small. At least not by any front running teams. They all are on the modern strategy of low roll angle. How much they travel the front end depends on the ride height rules of each series. They are all getting the nose on the ground during dive, if the rules allow.

    Where old school conventional strategies are still common is the lower ranks of racing from AutoX, grassroots road racing to short oval tracks. But the change is happening there too currently. I see it. There is a trickle down process of knowledge. Eventually a racer in each series tests & works out a modern suspension for their car ... and wins ... and slowly the evolution happens. As with any change, there is resistance by some people, and acceptance by others. This migration to the new strategy takes time ... years in fact. Again, I've seen it firsthand.

    The cars you have seen run so well with old school conventional set ups are using the first strategy, have it worked it all out & fine tuned it to its optimum. It wouldn't be as fast as a car with a modern high travel/low roll suspension that was also worked all out & fine tuned it to its optimum ... but it would faster than those that aren't.

    So to summarize, you can make either the conventional or modern set-up work on all types of tracks. If each suspension is well designed & tuned to its optimum, the modern set-up will carry more corner speed & provide a slight competitive advantage.

    .
    Last edited by Ron Sutton; 12-30-2014 at 08:56 AM.
    Feel free to chime in or ask technical questions. I am here to help where I can.

    Ron Sutton

    Ron Sutton Race Technology
    Your One Stop, Turn & Go Fast, Car Building Resource Center for Autocross, Track, Road Racing & Triple Duty Pro-Touring Cars

    Check out our 400 Page Car Building Catalog HERE

    Features: Suspension, Chassis, Cages, Brakes, Rear Ends, Engines, Transmisssions, Aero & Much, Much More!

  5. #5
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    The discussion about springs is quite involved.
    More than most people would think … with something as seemingly simple as springs. This is going to be controversial … because there are new* concepts … and there will be people who have run traditional** spring packages for decades … that have worked well for them … they have been successful with traditional** spring packages … and they don’t understand the new concepts & technology.

    When anyone has run something for years … that has worked well for them … changing to something new & “supposedly” better … and re-learning new concepts … doesn’t come easy. For those following along … I’m not suggesting you change anything. I’m simply willing to share these somewhat new, yet vastly proven suspension concepts with you … and you can decide what you want.

    After you learn about this … simply go with what makes sense for you & what works best for your goals. That’s a cool thing about hot rodding. One guy goes 3-link, another chooses a torque arm & another yet is debating over 3 versions of 4-links. And we all can be happy, enjoying our cars. Even competing against each other at an AutoX or track day event.

    What I really care about … in helping you learn this … is that you have fun with it … and get your car to better achieve your goals. Not my goals. Not anyone else’s. My goal here, is to help you achieve your handling goals with your car.

    -------------------------------------------------------------------------------------------------------

    Let’s get started with some key concepts:

    Weight transfer: Speaking literally … weight doesn’t transfer. I mean weight doesn’t unbolt itself and move around the car, re-attaching itself somewhere else just because you jumped on the brakes … I mean other than your coffee cup.

    What is really happening is the car’s weight mass at the CG is acting on the roll & pivot axis of the car and applying “Force” when the driver tries to get the car to stop, turn or accelerate. Calling it “Weight Transfer” is simple & easier for most of us to understand … and I prefer it. So we’re calling it Weight Transfer.

    Static weight & weight transfer (Force) combine to define the load on the car’s 4 tires. Load applied to a tire … adds grip to that tire. More load equals more grip … up to the point of overloading the tire. As we add load to one tire, we are reducing the load on another tire. Understanding this is key. Whatever you car weighs … 3000#, 3500#, whatever … that’s what you have to work with … and only that to work with.

    With the exception of aerodynamics … suspension components & geometry tuning are the primary tools we have to work with in controlling weight transfer from tire(s) to tire(s).

    Reminder: You’re not creating the Force. The Force already exists when you try to stop, turn or accelerate a 3500# car. When you step on the brakes, Force will make the front end want to compress (dive) & the back end want to lift … also known as “pitch.”. You’re just using the tuning tools available to influence how fast & how far the front end dives & the rear end lifts. When you steer the car hard left or right … Force will make the car roll about its roll centers. You’re just using the tuning tools available to influence how fast & how far the car rolls. On corner exit, under power … you get it.

    We have many tools to use, to influence chassis pitch & roll, including springs, sway bars, shocks, adjustable roll centers, weight placement, ride height, suspension arm or link geometry, track width, wheel base, etc, etc. Some are “built in” & some are tunable. For this section I’m focused on springs, ARB’s (Sway Bars) & shocks.

    Captain Obvious says … when you brake in a straight line weight transfers from both rear tires to both front tires. When you brake & turn at the same time, weight primarily transfers from the inside rear tire to the outside front tire. When you are turning, with no braking force, weight is transferring from the inside tires to the outside tires. As you accelerate out of the corner, weight transfers primarily from the outside front corner to the inside rear corner. As you unwind the steering wheel to straighten the car, but are still accelerating, weight transfer is from the front tires to the rear tires.

    .
    Feel free to chime in or ask technical questions. I am here to help where I can.

    Ron Sutton

    Ron Sutton Race Technology
    Your One Stop, Turn & Go Fast, Car Building Resource Center for Autocross, Track, Road Racing & Triple Duty Pro-Touring Cars

    Check out our 400 Page Car Building Catalog HERE

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  6. #6
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    This next part is instrumental in understanding your role as a tuner. Where weight is transferring TO … is loading the tire more … and increasing tire grip/traction at that tire. Where ever weight is transferring FROM … is loading that tire less … and decreasing tire grip/traction at that tire.

    You need to optimize the “balance of the grip” of all 4 tires at each stage of the corner (entry-middle-exit). So you don’t want to over load some tire(s) & underload other tire(s). You’re tuning the car to find the optimum “balance of the grip.”

    Tires are your only contact with the pavement. Grip is speed. Using all four tires will be faster than just using two. You just have to work out where to increase load/grip & where to decrease load/grip … and how much.

    So how do you work a tire more?
    The further the suspension travels … the more weight is transferred TO that end or corner of the car, putting more load & grip on the tire(s) at that end or corner. And more weight is transferred FROM the opposite end or corner, reducing the load & grip on the tire(s) at that end or corner.

    Here are some basic examples utilizing ONLY SPRINGS as the tuning tool & ASSUMING the Roll Angle is kept optimum with other tuning tools.
    Such as sway bars, CG height, roll centers, track width, etc.

    As you brake in a straight line the front springs allow weight transfer from both rear tires to both front tires.
    • Softer front springs allow the front end to travel more, putting more load/grip on both front tires & reducing load/grip on both rear tires.
    • Stiffer front springs allow the front end to travel less, putting less load/grip on both front tires & retaining more load/grip on both rear tires.

    When you brake & turn at the same time, the outer front spring primarily allows weight transfer from the inside rear tire to the outside front tire.
    • Softer front springs allow more travel, putting more load/grip on the outside front tire & reducing load/grip on the inside rear tire.
    • Stiffer front springs allow less travel, putting less load/grip on the outside front tire & retaining more load/grip on the inside rear tire.

    When you are turning, with no braking force, the outside front & rear springs allow weight transfer from the inside tires to the outside tires.
    • Softer front & rear springs allow more travel, putting more load/grip on the outside tires & reducing load/grip on the inside tires.
    • Stiffer front & rear springs allow less travel, putting less load/grip on the outside tires & retaining more load/grip on the inside tires.
    • Softer front & stiffer rear springs put more load/grip on the outside front tire & reducing load/grip on the inside front tire … while putting less load/grip on the outside rear tire & retaining more load/grip on the inside tires.
    • Stiffer front & softer rear springs put less load/grip on the outside front tire & retaining more load/grip on the inside front tire … while putting more load/grip on the outside rear tire & reducing load/grip on the inside tires.

    In most every situation in life & racing there are “exceptions to the rule” … this is one of them. What you read is not a typo. As you accelerate out of the corner, the inside rear spring WOULD allow weight transfer from the outside front corner to the inside rear corner … IF THE FORCE was that direction. But it’s not. The Force … when accelerating out of a turn, while still turning … is to the outside & rear. So there is NO FORCE pushing the car onto the left rear … yet. BUT … for optimum acceleration you still need to utilize all the potential grip available with the inside rear tire. So …
    • Stiffer rear springs keep the inside tire engaged more retaining more load/grip on the inside rear tire.
    • Softer rear springs lessen the inside tire’s engagement more reducing load/grip on the inside rear tire.

    As you unwind the steering to straighten the car, but are still accelerating, NOW there is weight transfer to the insider rear tire as the car flattens out.
    • Softer rear springs allow the rear to travel more, putting more load/grip on both rear tires & reducing load/grip on both front tires.
    • Stiffer rear springs allow less travel, putting less load/grip on both rear tires & retaining more load/grip on both front tires.

    Did you notice some conflicts? That’s what makes this challenging in finding the best compromise … the best “balance of the grip.”

    -------------------------------------------------------------------------------------------------------

    Let’s clarify some things …

    Corner Entry:
    1. Softer front springs put more load & grip on the front tires for better turning ability.
    2. Stiffer front springs keep more load & grip on the rear tires allowing the driver to drive into the corner deeper & brake harder.
    3. Too soft of front springs do not allow the driver to go in as deep & brake as hard. Optimizing the brake bias & shock package helps.
    4. Too stiff of front springs makes the car push on entry due to low load & grip on the front tires
    5. Rear springs are left out, because their primary role here is working with the rest of the suspension for optimum Roll Angle.

    Mid Corner:
    1. Softer front springs put more load & grip on the front tires … allowing for higher cornering speeds … allowing softer braking on entry.
    2. Stiffer front springs keep more load & grip on the rear tires … requiring lower cornering speeds … requiring more braking on entry.
    3. Too soft of front springs make the car loose in the middle of the corner due to low load & grip on the rear tires.
    4. Too stiff of front springs makes the car push in the middle of the corner due to low load & grip on the front tires.
    5. Softer rear springs put more load & grip on the rear tires for more traction.
    6. Stiffer rear springs keep more load & grip on the front tires for better turning ability.
    7. Too soft of rear springs can unload the inside front tire & make the car tight or pushy.
    8. Too stiff of rear springs can unload the outside rear tire & make the car free or loose.

    Corner Exit:
    1. Softer rear springs put more load & grip on the rear tires for more traction.
    2. Stiffer rear springs keep more load & grip on the front tires for better turning ability.
    3. Too soft of rear springs can make the car push on corner exit due to low load & grip on the front tires.
    4. Too stiff of rear springs can make the car loose on corner exit due to low load & grip on the rear tires.
    5. Front springs are left out, because their primary role here is working with the rest of the suspension for optimum Roll Angle.

    -------------------------------------------------------------------------------------------------------

    On the suspension set-up menu, your choice … pick just ONE.
    • Stiffer front springs let you drive in deeper … but gets tight/pushy in the middle requiring lower corner speeds.
    • Softer front springs require you to brake softer … but turns much better in the middle allowing higher corner speeds.
    • Moderate rate front springs to achieve a balanced compromise between the two strategies.

    .
    Feel free to chime in or ask technical questions. I am here to help where I can.

    Ron Sutton

    Ron Sutton Race Technology
    Your One Stop, Turn & Go Fast, Car Building Resource Center for Autocross, Track, Road Racing & Triple Duty Pro-Touring Cars

    Check out our 400 Page Car Building Catalog HERE

    Features: Suspension, Chassis, Cages, Brakes, Rear Ends, Engines, Transmisssions, Aero & Much, Much More!

  7. #7
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    Suggested Books

    If you desire to learn about chassis set-ups & suspension tuning, there are chassis & suspension books... covering design, engineering, theories, tuning, etc ... I think the right book for a person depends on how in-depth they plan to get. There are great books, good books, ok books & horrible books written on the subject. Some books contain old school information ... some newer technology ... and some in-between.

    I often recommend books, but the right one depends on the person's goals.
    Based on you being new to all of this, I would recommend these books, in this order. If at any point, it's get so complex, you're not enjoying it, that's a place to stop. On the other hand if you become hungry for more in-depth knowledge, then work your way through the list.

    1. Herb Adams was the "go-to" guy in the 70's & 80's. Technology has advanced quite a bit, but this book is an excellent starting point. It's a good read & much of it is still relevant. Just be open minded that some suspension set-ups have advanced & changed dramatically. Go HERE.

    When it comes to books, they're all behind what professional race teams are doing. Top race teams with 30 Engineers, full Research & Development staffs & state-of-the-art testing technology ... are understandably reluctant to share info ... until it's so old it won't hurt them competitively. So with books, there will always be a lag.

    Steve Smith race suspension books are the easiest to understand & have somewhat up to date stuff. Don't ignore it because it's oval track. While there are some differences ... handling is handling ... and NASCAR teams utilize cutting edge technology today. I recommend two books from them.

    2. Here
    3. Here

    4 & 5.
    The best books ever are from Carroll Smith (passed away several years back). They are a little hard to read, for a rookie & non-engineer, but a very solid foundation. The two I suggest you start with are "Engineer to Win" & "Tune to Win." Go HERE.

    6. Finally, the most complex, in engineering speak, is from Milliken & Milliken, titled Race Car Vehicle Dynamics. See it HERE.

    I have found this forum & Pro Touring people in general to be both knowledgeable & open to sharing. So don't be afraid to simply ask guys. You'll find they're open with information until you get close to beating them, and you have to figure out the last stuff all by yourself. Which is how it should be in a competitive environment.

    .
    Last edited by Ron Sutton; 12-22-2014 at 03:27 PM.
    Feel free to chime in or ask technical questions. I am here to help where I can.

    Ron Sutton

    Ron Sutton Race Technology
    Your One Stop, Turn & Go Fast, Car Building Resource Center for Autocross, Track, Road Racing & Triple Duty Pro-Touring Cars

    Check out our 400 Page Car Building Catalog HERE

    Features: Suspension, Chassis, Cages, Brakes, Rear Ends, Engines, Transmisssions, Aero & Much, Much More!

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    Great post. I'm very much new to PT cars in general as most of my experience comes from modern muscle and sports cars.
    I've had quite a few of them and spent time at the drag strip, autox and track days in all of them so setting up a car that wasn't designed to handle nearly as well as some of the modern stuff will be a learning experience and challenge for me. Certainly more so than dialing in a C4 corvette for autox.

    Reading your posts above made me think of the two C4 corvettes that I would autox in and how they were similar but very different. Your old school vs new school post.
    One had stiff springs and ARB with fairly stiff shocks. A Z51 1990 while the other, A base suspension 1996 was a soft spring and slightly less stiff ARB. One was flat and predictable. The other was more challenging, you could drive it deeper into a corner by putting a lot of weight transfer onto the front end with the brakes. It had lots of nose dive. If you got it wrong or misjudged it though...
    Last edited by Dr. Evil; 12-08-2014 at 09:11 PM. Reason: I cant spell properly
    1969 Wife, all stock no mods. Factory redhead package.
    2005 Son. Blond headed, blue eyes with factory hell on wheels package.
    A couple of cars too.

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    I noticed that Tires is # 1 on your list of 20 critical tuning concepts. What can tire temps tell us? Lets say I pull in the hot pits mid session and record the temps. How should it be done and what changes should be made based on the observations? I run 60 TW Yokohamas but the majority of members here that also might track their car are likely to run 200+ treadwear tires since the groups promoting PT participation at events have 200 TW limits. Any differences in recommended changes based on whether the car has race slicks, DOT R's, or street tires? Any other thoughts on tires?

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    Ron, Thanks!!

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    This is probably the first time I have seen anyone recommend the Steve Smith books. They actually are a very good starting point for most guys but are discounted because of their oval track focus. Building the Pro Stock late Model Sportsman is also a good starting point for anyone running stock based GM sub-frame cars. I've run through a various number of his books and ended up with those two you mention as the ones I check in on most regularly.


    Quote Originally Posted by NOT A TA View Post
    I noticed that Tires is # 1 on your list of 20 critical tuning concepts. What can tire temps tell us? Lets say I pull in the hot pits mid session and record the temps. How should it be done and what changes should be made based on the observations? I run 60 TW Yokohamas but the majority of members here that also might track their car are likely to run 200+ treadwear tires since the groups promoting PT participation at events have 200 TW limits. Any differences in recommended changes based on whether the car has race slicks, DOT R's, or street tires? Any other thoughts on tires?
    The tire temps will tell you exactly how the tire in interacting with the road surface and give you a point of reference of where to start looking to initiate changes to improve the contact patch. As Ron has mentioned in this and other posts, you want a log book to compile the information in as you want to reference the temps and changes and chart progression. You will want a probe style temperature device to get just under the surface. You will want to check three spots across the tread face; outside, middle, and inside. What you do with the info depends on what the temps tell you. Basically you will want to minimize the hot areas, put more heat into cool areas, and get consistent temps across the tread. This will typically involve alignment changes or highlight potential geometry problems, but looking at the whole picture of relative temps between the four tires can also indicate spring rate changes or changes in weight distribution that may be needed to even out temps.
    TonyC@HP2

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    Quote Originally Posted by Dr. Evil View Post
    Great post. I'm very much new to PT cars in general as most of my experience comes from modern muscle and sports cars.
    I've had quite a few of them and spent time at the drag strip, autox and track days in all of them so setting up a car that wasn't designed to handle nearly as well as some of the modern stuff will be a learning experience and challenge for me. Certainly more so than dialing in a C4 corvette for autox.

    Reading your posts above made me think of the two C4 corvettes that I would autox in and how they were similar but very different. Your old school vs new school post.
    One had stiff springs and ARB with fairly stiff shocks. A Z51 1990 while the other, A base suspension 1996 was a soft spring and slightly less stiff ARB. One was flat and predictable. The other was more challenging, you could drive it deeper into a corner by putting a lot of weight transfer onto the front end with the brakes. It had lots of nose dive. If you got it wrong or misjudged it though...

    If I understood your post correctly ... and there's a good chance I didn't ... you had a car with stiff springs & stiff sway bars , versus a car with soft springs & sway bars. Of course us using the terms stiff & soft is not very precise. Like saying hot & cold. But in racing circles, winning teams run EITHER ...

    A. Stiff front springs & small to moderate sway bar ... with softer rear springs are small to no sway bar ... traveling the front crossmember "around" 1 inch in dive & rolling around 3°.
    B. Softer front springs & big/monster sway bars ... with stiffer rear springs with a small sway bar ... traveling the front crossmember "around" 3" in dive & rolling around 1°.
    C. Somewhere in-between.

    But running a flatter car ... less roll angle ... works all four tires better, as well as providing a more drivable, confidence inspiring car.




    Feel free to chime in or ask technical questions. I am here to help where I can.

    Ron Sutton

    Ron Sutton Race Technology
    Your One Stop, Turn & Go Fast, Car Building Resource Center for Autocross, Track, Road Racing & Triple Duty Pro-Touring Cars

    Check out our 400 Page Car Building Catalog HERE

    Features: Suspension, Chassis, Cages, Brakes, Rear Ends, Engines, Transmisssions, Aero & Much, Much More!

  13. #13
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    Hi John!

    Quote Originally Posted by NOT A TA View Post
    I noticed that Tires is # 1 on your list of 20 critical tuning concepts.
    Yes sirree #1 with a bullet. Most everything we do with the suspension is about loading or unloading the tires. Our suspension geometry goals revolve around loading the tires evenly. And our steering geometry is mostly about achieving optimum slip angle for grip.

    What can tire temps tell us? Lets say I pull in the hot pits mid session and record the temps. How should it be done and what changes should be made based on the observations? I run 60 TW Yokohamas but the majority of members here that also might track their car are likely to run 200+ treadwear tires since the groups promoting PT participation at events have 200 TW limits. Any differences in recommended changes based on whether the car has race slicks, DOT R's, or street tires? Any other thoughts on tires?

    Whew! ... Holy Cow John! ... LOL ... This would be a book in itself.

    I'll list the major categories of tire performance knowledge we can discuss
    ... and then answer your first question today about what can tire temps tell us. We can continue the discussion in the other categories of tire performance one step at a time. Of course I going to write this in a way everyone can follow along with us & learn in a way that helps them with their cars.

    Major categories of tire performance:
    • Understanding How Slip Angle Defines Grip ... and how to optimize it
    • Understanding How Dynamic Camber* Defines Grip ... and how to optimize it
    • Understanding How G-Forces, Roll, Pitch & Diagonal Roll Defines Loading, Grip & Handling Balance ... and how to optimize them
    • Understanding How Tire Pressure, Rim Width & Sidewall Construction Affect the Tire Spring Rate & Slip Angle ... and how to optimize them
    • Understanding the Rubber Mixture Used in Tires - How to Care for Them Best & How to Know When They're Dead

    * Don't confuse "dynamic camber" with camber gain. Camber gain is 1 of 8 items that define the dynamic camber.

    -----------------------------------------------------------------------

    For this post, I'll keep the discussion to tire pressures & temps. First, we 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. If it is a tire I did the testing on, as long as I know the car weight, I can be pretty close to start.

    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, use a memory tire pyrometer to take all 12 readings ASAP. Put 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 capture these numbers for review. Most guys already 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. There are exceptions to this rule, but it's usually to band-aid something.

    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 and 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.

    This next part, I copied over from my Front Suspension Thread, as it primarily deals with tuning on the front geometry to optimize the front tire contact patches.
    It definitely applies to the rear tires, but obviously straight axle rear ends are typically a little harder to tune

    ----------------------------------------------------------------------------------------------------------------------

    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, my race teams 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 expensive. 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.

    --------------------------------------------------------------------------------------------------

    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.
    For a lot less expensive version with no memory, but just as accurate, go HERE.
    For a combo unit ... infrared for brakes & probe for tires go HERE.

    Do not use an infrared temp gun for tires. 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 pryometer for tires.

    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: If you run slicks ... many 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. Ask me how I know this.

    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.

    Let’s run through some examples … assuming we have a PT track car on a road course running equal size Hoosier R6/R7 tires front & rear … with an optimum tire temp around 190 degrees. I’ll start with the basics & progress. Here is what the tire temps tell me

    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 to for a higher roll angle on LH turns & lower roll angle on RH turns or some combination.

    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: [/B]Either due to track or driver, the car is exiting some RH corners easier or gentler.

    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 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.

    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.

    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.”

    Make sense so far?


    Feel free to chime in or ask technical questions. I am here to help where I can.

    Ron Sutton

    Ron Sutton Race Technology
    Your One Stop, Turn & Go Fast, Car Building Resource Center for Autocross, Track, Road Racing & Triple Duty Pro-Touring Cars

    Check out our 400 Page Car Building Catalog HERE

    Features: Suspension, Chassis, Cages, Brakes, Rear Ends, Engines, Transmisssions, Aero & Much, Much More!

  14. #14
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    Hi Tony,

    Quote Originally Posted by High Plains Mopars View Post
    This is probably the first time I have seen anyone recommend the Steve Smith books. They actually are a very good starting point for most guys but are discounted because of their oval track focus. Building the Pro Stock late Model Sportsman is also a good starting point for anyone running stock based GM sub-frame cars. I've run through a various number of his books and ended up with those two you mention as the ones I check in on most regularly.
    Like you, I find the oval track books are more specific, which can be helpful to a novice. The road racing books tend to be very general & theoretical, which is harder for a novice. Turning corners is turning corners, you just have to take the stuff that oval track racers do specifically to go left.


    The tire temps will tell you exactly how the tire in interacting with the road surface and give you a point of reference of where to start looking to initiate changes to improve the contact patch. As Ron has mentioned in this and other posts, you want a log book to compile the information in as you want to reference the temps and changes and chart progression. You will want a probe style temperature device to get just under the surface. You will want to check three spots across the tread face; outside, middle, and inside. What you do with the info depends on what the temps tell you. Basically you will want to minimize the hot areas, put more heat into cool areas, and get consistent temps across the tread. This will typically involve alignment changes or highlight potential geometry problems, but looking at the whole picture of relative temps between the four tires can also indicate spring rate changes or changes in weight distribution that may be needed to even out temps.
    Yup yup!




    Feel free to chime in or ask technical questions. I am here to help where I can.

    Ron Sutton

    Ron Sutton Race Technology
    Your One Stop, Turn & Go Fast, Car Building Resource Center for Autocross, Track, Road Racing & Triple Duty Pro-Touring Cars

    Check out our 400 Page Car Building Catalog HERE

    Features: Suspension, Chassis, Cages, Brakes, Rear Ends, Engines, Transmisssions, Aero & Much, Much More!

  15. #15
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    Mar 2007
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    Thanks Ron, excellent post. I'll admit that years ago I tried the laser guided infrared temp gun route and gave up. ahahaha

    "Whew! ... Holy Cow John! ... LOL ... This would be a book in itself."

    ^^^Hence the reason for my request. We hear so much about brakes, drivetrain, and suspension mods like 3 link, 4 link, truck arm, coil overs, and on and on yet hear very little about the difference tires can make even though they are arguably the biggest factor in making the car handle better.

    "Make sense so far?"

    Yes please continue!

  16. #16
    Join Date
    Apr 2005
    Location
    Colorado Springs
    Posts
    741

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    How important is the tire contact patch, tire pressure, and the suspension acting on it? It's critical.

    Below is the contact patch of a 26x12 street radial under a 3200# car with 35 psi in it. That's not much contact area when you think about it.

    TonyC@HP2

  17. #17
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    Oct 2012
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    Very interesting Ron. Especially the new vs old systems as I am learning with my new ride.

    Question;

    As the majority of time I'm AutoX it seems like there isnt enough time on the track to generate tire heat. I see a lot of folks marking the sides of their tires with chalk and seeing how far they roll the tires over. With inclement weather temps are also hard to measue so how does the chalk "talk" to us and what is our "goal/objective"

    Thanks as always.
    I've been away learnning & racing but back to learn more before next racing season. My '67 is coming VERY slowly but I'm learning and having fun with my ZL1. Damn weight is a Bit*h is what I now know.
    Todd
    '14 ZL1, 6 speed and 6.2L of Super Charged Awesome!
    '67 Camaro SS in process. A long, slow, expensive trip...


    How hard can it be...

    Project Obsession
    http://www.pro-touring.com/showthrea...ject-Obsession

  18. #18
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    Nov 2012
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    Hi Todd !

    Quote Originally Posted by Todd in Vancouver View Post
    Very interesting Ron. Especially the new vs old systems as I am learning with my new ride.

    Question;

    As the majority of time I'm AutoX it seems like there isnt enough time on the track to generate tire heat. I see a lot of folks marking the sides of their tires with chalk and seeing how far they roll the tires over. With inclement weather temps are also hard to measure so how does the chalk "talk" to us and what is our "goal/objective"

    Thanks as always.
    I've been away learnning & racing but back to learn more before next racing season. My '67 is coming VERY slowly but I'm learning and having fun with my ZL1. Damn weight is a Bit*h is what I now know.

    I use tire crayons AND tire temps together. I use a the yellow tire crayon to make a rectangle that goes from 1/2" onto the tread ... then rolls down over the edge of the tread to about 1" of tread side block & sidewall. I do this on the inside & outside edges of all 4 tires. When the car comes back in from a run, I visually inspect all 8 points where the crayon was. I say "was" ... because most of the crayon will be gone. I am looking to see how much of the tire "over the edge of the tire tread block" is actually running on the track surface.

    I don't think of this as how far the tire is rolling over, but it does tell you that. I'm looking to see three things:
    1. Am I using the full contract patch of the tire.
    2. Am I in the sweet spot of utilizing the the edge of the tire tread block?
    3. Is my camber & caster correct?

    Frankly, to do this accurately also requires tire temps, which is why I do these together initially. Refer to the tips for reading tire temps in post #13. After I am confident I have these three things ... I am using the full contract patch of the tire ... I am in the sweet spot of utilizing the the edge of the tire tread block ... and my camber & caster is correct ... then I stop using the tire crayon & simply take tire temps every run.



    Feel free to chime in or ask technical questions. I am here to help where I can.

    Ron Sutton

    Ron Sutton Race Technology
    Your One Stop, Turn & Go Fast, Car Building Resource Center for Autocross, Track, Road Racing & Triple Duty Pro-Touring Cars

    Check out our 400 Page Car Building Catalog HERE

    Features: Suspension, Chassis, Cages, Brakes, Rear Ends, Engines, Transmisssions, Aero & Much, Much More!

  19. #19
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    I just wanted to jump in here quickly with some real hands on feedback for the work that Ron is doing. As some may know (but more probable don't) I commissioned Ron to review the suspension (and brakes - as part of one of his packages) on the OneLapCamaro in December. He sent over a fairly lengthy list of measurements that we worked through at Raymond's Performance and got the data back to Ron in early January. He put the data through a model and came up with the following observations:

    - the static roll center height was too low, causing too much roll angle
    - the dynamic roll center height in dive and roll was too low, causing too much roll angle
    - anti-dive was too low (causing, wait for it, too much roll angle)
    - caster/camber/KPI was not optimized
    - ackerman was low
    - front suspension geometry had a jacking effect and a higher front roll angle
    - rear roll center was too high
    - rear shock mounts were off by a fraction of an inch

    He provided a very comprehensive set of diagrams showing the issues and explaining, in depth, the "cause and effect" and then went to work on solutions.

    He then provided a "guide" as to how to fix as much of the issues as my budget allows (collectively we think we got about 75% of what was on the table for very little investment. A short list of what we did was:

    - Moved the front subframe
    - Moved the steering rack
    - Changed lower ball joints
    - Changed (revalved) shocks
    - Changed springs/spring rates
    - Changed the front sway bar
    - Raised the rear roll center using the 3-link
    - Tweaked the shock mounting position

    We got it done just before the USCA Thunderhill event and I wish I could tell you that I have incontrovertible proof of our success but, as often happens, we had a couple of issues that sent us too the track without being exactly were we wanted to be - we had an issue with the front springs and had to make due with a slightly lighter rate and the front sway bar arms were not long enough to get us to the stiffest, and preferred setting for the road course.

    The fact that I blew the engine on the 2nd lap of on the road course also limited my ability to show how good the car was. FML

    But - the car was awesome and was, in all honesty, a new car as compared to the old setup. And keep in mind - we had the stock subframe very well sorted out but we never had the time/opportunity to fine tune the AME subframe the same way. Ron's work accelerated our program by at least a year.

    And to be honest, on the autocross and speed stop the car was pretty damn good. Jake R., Mike M. and I were 0.4 seconds apart (1st to 3rs) on the autoX (OK, not that great) and 0.09 seconds on the speed stop.

    Hopefully I will have the ability to compare more at Las Vegas next month which will be good since I can actually compare it to USCA last year and provide a more absolute interpretation of the changes for you then.

    If anyone has any specific questions please let me know. We can always look at creating a dedicated thread to look at the data (or at least some of the data )

    Cheers
    James
    1967 Camaro RS - The OLC
    1989 Camaro 1LE - The CMC Car
    1989 Camaro 1LE R7U - The Players Car

  20. #20
    Join Date
    Nov 2006
    Location
    Mountain Springs, Texas
    Posts
    2,094
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    Quote Originally Posted by James OLC View Post
    I just wanted to jump in here quickly with some real hands on feedback for the work that Ron is doing. As some may know (but more probable don't) I commissioned Ron to review the suspension (and brakes - as part of one of his packages) on the OneLapCamaro in December. He sent over a fairly lengthy list of measurements that we worked through at Raymond's Performance and got the data back to Ron in early January. He put the data through a model and came up with the following observations:

    - the static roll center height was too low, causing too much roll angle
    - the dynamic roll center height in dive and roll was too low, causing too much roll angle
    - anti-dive was too low (causing, wait for it, too much roll angle)
    - caster/camber/KPI was not optimized
    - ackerman was low
    - front suspension geometry had a jacking effect and a higher front roll angle
    - rear roll center was too high
    - rear shock mounts were off by a fraction of an inch

    He provided a very comprehensive set of diagrams showing the issues and explaining, in depth, the "cause and effect" and then went to work on solutions.

    He then provided a "guide" as to how to fix as much of the issues as my budget allows (collectively we think we got about 75% of what was on the table for very little investment. A short list of what we did was:

    - Moved the front subframe
    - Moved the steering rack
    - Changed lower ball joints
    - Changed (revalved) shocks
    - Changed springs/spring rates
    - Changed the front sway bar
    - Raised the rear roll center using the 3-link
    - Tweaked the shock mounting position

    We got it done just before the USCA Thunderhill event and I wish I could tell you that I have incontrovertible proof of our success but, as often happens, we had a couple of issues that sent us too the track without being exactly were we wanted to be - we had an issue with the front springs and had to make due with a slightly lighter rate and the front sway bar arms were not long enough to get us to the stiffest, and preferred setting for the road course.

    The fact that I blew the engine on the 2nd lap of on the road course also limited my ability to show how good the car was. FML

    But - the car was awesome and was, in all honesty, a new car as compared to the old setup. And keep in mind - we had the stock subframe very well sorted out but we never had the time/opportunity to fine tune the AME subframe the same way. Ron's work accelerated our program by at least a year.

    And to be honest, on the autocross and speed stop the car was pretty damn good. Jake R., Mike M. and I were 0.4 seconds apart (1st to 3rs) on the autoX (OK, not that great) and 0.09 seconds on the speed stop.

    Hopefully I will have the ability to compare more at Las Vegas next month which will be good since I can actually compare it to USCA last year and provide a more absolute interpretation of the changes for you then.

    If anyone has any specific questions please let me know. We can always look at creating a dedicated thread to look at the data (or at least some of the data )

    Cheers
    So now it seems that these aftermarket subframes that were light years ahead of the stock subframes now need extensive rework. Are these mods necessary for your average guy running an occasional autocross or are they only needed for advanced drivers on hardcore road courses etc? Any downside for street driven cars?

    Thanks,
    Don
    1969 Camaro - LSA 6L90E AME sub/IRS
    1969 Camaro convertible - LS3 4L65E Ridetech Level 2 Tru-Turn
    1959 El Camino project

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