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Unread 07-23-2013, 11:45 AM
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Ron Sutton Ron Sutton is offline
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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 race 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 … but for Pete’s sake we don’t want any more threads asking who I am.

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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: Designing Aerodynamics for Track Performance ... click HERE.
For a thread focused on: Safety for Pro-Touring Track Cars ... 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.

.
__________________
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!

Last edited by Ron Sutton : 12-07-2014 at 05:25 PM.
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Unread 07-23-2013, 11:47 AM
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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.


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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

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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!

Last edited by Ron Sutton : 12-06-2014 at 06:47 PM.
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Unread 07-23-2013, 11:48 AM
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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!
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Unread 07-23-2013, 11:49 AM
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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.

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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 & underworks 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.

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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.

.
__________________
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!

Last edited by Ron Sutton : 12-30-2014 at 11:55 AM.
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Unread 07-23-2013, 11:50 AM
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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.

.
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Last edited by Ron Sutton : 12-06-2014 at 04:35 PM.
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Unread 07-23-2013, 11:52 AM
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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.

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

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

Last edited by Ron Sutton : 12-06-2014 at 04:48 PM. Reason: Clarification
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Unread 07-23-2013, 11:56 AM
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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.

.
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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!

Last edited by Ron Sutton : 12-22-2014 at 06:26 PM.
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Unread 07-23-2013, 01:30 PM
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Default Thanks for taking

the time to be the "bus driver" and taking us to school.

When you speak of a soft spring vs. stiffer spring, how big of a swing are you speaking/writing? I know of Corvette guys running C5's with 1200 lbs front and 900 lbs rear that are very fast. Seen guys more in the 700/800 range in the front fast as well. Assuming the above mentioned is 3000 pounds car weight.
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Unread 07-23-2013, 04:16 PM
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Default shock dampening question

I just read through all of your posts here this morning. This is great stuff… very well written and understandable for someone like myself that is fairly new to car building, and driving on road courses. Four years ago I joined a sports car club and went through a basic driver training course and learned about driving the proper lines, braking, tire contact patch, weight transfer, and some basic car set up like you have described. Now I am hooked on this sport and trying to improve in my driving and car set up.

I have a 69 Camaro that has been modified similar to a lot of cars on here, with modern engineered chassis and suspension components, bigger brakes, modern tires and wheels… etc. My car weighs ~3,400 lb with 53% of the weight on the front. I have 600 lb coils on the front with 240 lb/in leafs on the back.

Here is my question… If I wanted to set my car up for running on road courses primarily, and use the new school set up that you defined, what would be a good starting point for setting up the compression and rebound dampening for the front and rear shocks?

If I had 10 clicks of adjustment with “1” being the least dampening and “10” the most, what would be a good starting point for setting up the dampening in the shocks?

Front compression dampening: 1 thru 10?
Front rebound dampening: 1 thru 10?
Rear compression dampening: 1 thru 10?
Rear rebound dampening: 1 thru 10?

I am just trying to understand the basics of shock dampening, and how different dampening settings affect the handling of the car. At this point I know nothing about adjustable shocks since I have only run “Tuned Shocks”. I plan to invest in a set of adjustable shocks for my next upgrade, so I want to have some logic to use as a starting point for the adjustment.

Thanks again for taking the time to write up all this great information… much appreciated
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Unread 07-23-2013, 05:23 PM
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This needs to be included in a book. I think I can learn something here. Subscribed.
And thanks for taking the time to bring all this forward. It's always better to deal with an educated customer!
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