Curing understeer - racer feedback please
 

Ok, so I just got adjustable shocks.

If I want to decrease understeer, should I make the rear stiffer than the front, or the front stiffer than the rear?

There's a grid around somewhere that shows what to do with your geometry/suspension to cure what handling problems. I think it was either petite or pineapple racing. Chcek their websites or try searching the forums for it.

Understeer?

What size tires/wheels are you running, and what tire pressures? It's not very common to fight understeer with these cars.

could be alot of things.
tire pressure too low (so the tire will roll over easily and you're seeing how well your sidewall grips)
front sway bar too stiff compared to the rear
if you are running aftermarket wheels, did you go to a narrower width? or did you go to staggered widths between frnt and rear, if so, how much.
what kind of tires are you running? are they worn out? warmed up properly? (depending on tire type)

Guys - please focus on the original question for now.

To reduce understeer, should the front shocks be set stiffer than the rear, or should the rear shocks be stiffer than the front.

Thanks.

The FD, like most other factory car, has a built in understeer. This is for the safety of the average non-racing trained driver. What it does, in case you enter into a corner too fast, it wants to go straight (push, or understeer) forcing you to turn the steering wheel more, thereby crossing the tires up more, which in turn, will rub some speed off and allow you to make the turn, within limits of error. It also makes the car's handling uncomfortable and non precise. It is a "safe" handling mode and the manufacturer's build them this way for liability reasons.

I have never had a car that did not initially understeer, much over my liking. The best compensation is not with shock settings but with a proper size, or adjustable, rear sway bar. By installing a larger, or stiffer bar in the rear, you can tune the handling towards neutral, regardless to tire size differences between the fronts and rears.

Be careful in the process; the car's handling will improve but, it will also be less tolerant to mistakes and will spin around easier.

I would not use shock settings to compensate for major understeer as you can get yourself into far more trouble with a non compliant dampening than the minor benefit you may get from it by small improvement in understeer.

If you have not done it yet, be sure to replace front and rear rubber sway bar mounting bushings with stiff poly, getting rid of the factory rubber ones. Those alone will make the car handle with more precision and they are cheap. Trade off is a bit harsher ride as you loose some independent suspension action between the left and ride sides of the car.

that was a good post. /\

Here's a link to a PDF on general suspension adjustment effects, including damper adjustments:

http://www.neohio-scca.org/comp_clin...ut%202005a.pdf

Dave

Yes, softer shock settings up front vs the rear would reduce understeer, but you should really listen to some of the statements made in this thread.

If you are really having a trouble with understeer, either something in your setup is creating it (big stagger difference in tire sizes or huge front anti-roll bar) or it's your driving technique.

Rule #1:

Don't try to fix a problem at one end of the car by screwing up the other end of the car.

If one end of the car isn't working then work on that end. Handicapping the "good" end should only be done as a last resort.

Ok, thanks everyone! I just wanted to get a better understanding of the pysics behind all this.

So a fatter roll bar would essentially stiffen the rear end, resulting in a lesser degree of understeer. I belive it.

I would have thought the opposite, however. You get more bite on the front end by putting more weight on the front tires. If you stiffen the front shocks, and soften the rears, then the front wheels would be fighting more of the weight of the car leaning over, right? So I figured that the front would get more 'bite' on the road. I guess it just doesn't work that way, but I'm not sure why.

Sammy,

you didn't answer the question. What's your current setup that you are getting so much understeer.

Wow, some interesting stuff on this link, namely:

-Rubber friction coefficient decreases as contact pressure increases.

http://www.neohio-scca.org/comp_clin...ut%202005a.pdf

I would have never guessed that to be the case!

I've read in driving manuals about weighting the front end of the car under braking to get more bite before turn-in. This appears to be a direct contradiction?

I have a bad wheel set up, so I went back to stock. I'm upgrading the tire sizes on the wheels, so no biggie.

This post is really about me trying to understand the physics of car handling more than specifically fixing my car. There's been a lot of great info posted =)

Is the R1/2 front sway bar identical to the base/touring?

Where can I find these polyurethane sway bar mounting bushings? I quick internet search didn't yield anything...without the purchase of front and rear bars.

TIA

Like so much in life, car handling is a compromise. It was shown in experiments that in order to get max tire grip, you want to allow the car to roll over onto the outside tires and increase the tire to ground contact force. Great, if you only going to run in circles and go for max G-force numbers. But, if you need to make transitions from left to right turns, as in most cases of race and winding road driving, you need to minimize the body roll and the resulting weight tranfers. It takes time to properly and smoothly transfer chassis weight from one side to the other. During these periods of weight transfer the car is at its most unbalanced states, due to various suspension movements and variations in those settings.

I had found that for the FD the stock front bar, combined with poly bushings were quite sufficient for roll resistance, particularly for any street speeds. At the same time, the rear bar is much too small to provide the needed balance between the front and the rear. With that small rear bar the weight transfers on the rear-end of the car will be greater, resulting in greater grip which, will not allow the rear end to come around in a neutral manner. So, in effect, with the larger rear bar you make the compromise of actually reducing the outside tire grip in order to obtain chassis balance.

Also, must remember that with soft bars and lots of roll, most of the tire-to-pavement contact is with the outside tires. You can, and actually will, lift the inside tires in a turn. With lot of roll stiffness, you reduce the outside tire contact pressures but, increase the inside tire contact pressures in the process, simply because you do not transfer all that much weight onto the outside tires.

With the proper chassis balance and roll resistance the car will transition much smoother and be altogether much faster and feel more precise for road courses. The ultimate amount of roll resistance truly depends on the driver's preference and driving style, as well as on environmental factors, such as track, tire selection and temperatures, etc...

Trying to adjust with you shocks, assuming a stock sway bar setup, you'd end up placing your rear shocks on max stiffness while keeping the front ones soft which could really get tricky and unpredictable in bumpy corners.

no, because the reason friction decreases with area of contact patch is because the weight is spread over a larger area hance pressure per square inch decreases creating less friction.

Braking increases the weight on the front of the car, thus increasing pressure per unit of area and thus friction.

Bushings can be purchased at most local speed shops, or even at places like JC Whitney's online catalog. Try searching places, like Summit racing. Measure your bar diameters and order the correct size. I just got some a few months ago for the front bar, pretty sure it was JCWhitney's. They normally arrive with the proper clamps that usually fit the stock mounting bolt patterns.

That is called "trail breaking" It is done to transfer weight onto the front tires to increase their grip while, at the same time, take weight OFF the rear tires to decrease their grip and thus, allow the rear end to rotate around.

What needs to be understood is that in the vast majority of car setup cases you can NOT obtain a perfect chassis balance that will be ideal for slow, as well as, fast corners. What setup work great at autocross speeds could give you the scare of your life in a 140MPH sweeper. Thus, what many racers prefer is to set up the car to be near neutral for the fastest road course corners where most time is gained or lost and just deal with the understeer in slow corners. Trail braking is one of the ways to deal with slow corner entry understeer.

Hey, what you say is true, but the comment I was referring to was not with regards to the contact patch, rather the adhesion properties of rubber in general. The link says rubber friction coefficient decreases with contact PRESSURE. Not area. I find this hard to believe, however.

Nope. Any car will generate the most grip when each tire is loaded equally. That means minimal weight transfer and is why racecars are built with the CG as low as possible along with nearly 50/50 weight distribution. This results in minimal weight transfer and tires loaded as equally as possible at all times.

Nope. Weight transfer has zero to do with body roll. You can adjust the amount of roll all you like and the effect on weight transfer will be zilch.

Nope. Bigger (stiffer) bars create greater weight transfer. Smaller bars create less weight transfer.

Now you've got it right. Bigger bars saturate the outside tire more quickly and this results in less grip on the outside tire. Bigger bars transfer more weight across the chassis, not less.

Never handicap the end of the car that IS working. Try to fix the end of the car that ISN'T working. Only handicap the good end as a last resort.

Nope. Stiffer bars are more apt to lift the inside tire. Cars with little roll resistance and lots of grip will merely ride the bumpstops on the outside of the turn, they will not lift the inside tire because there's not enough force through the bar to pick the tire up off the ground.

Nope again.

Depends. It's all balance. "Stiffer" and "softer" are relative terms, not absolutes. Without a shock dyno nobody knows what the absolutes are.

It's true. Note that as cF decreases that does not necessarily mean total grip decreases. That does sound contradicting but it's not. Increasing the load on a tire increases the grip even though it decreases cF. The increase in load (and the resulting increase in grip) is enough to overpower the slight decrease in cF so the end result is still more grip. As you continue to increase load on a tire grip of that tire continues to increase, albeit at a lesser and lesser rate.

https://www.rx7club.com/suspension-wheels-tires-brakes-archive-112/17-vs-18-racing-mind-narrow-vs-wide-tires-292194/

No, it's not a contradiction. If you double the downforce on a tire you do get more traction.

But

You do not get double the traction. Insead of 200% traction you get about 180% or 190%.

Oversteer and understeer are terms describing the relation between front and rear traction.

If one end of the car is stiffer, it will get more weight transfer. It will actually remove some of the weight transfer from the softer end of the car. Therefore the softer end of the car will end up with more traction relative to the stiffer end of the car.

When one end of the car is stiffer than the other end of the car, you are actually trading some of the traction from one end to the other. For example the soft end of the car might have 40% of the load but the load actually generates 45% of the traction while the stiff end of the car might get 60% of the load but the load only generates 55% traction . That's oversteer if the stiff end is in back.

In general you get more traction with softer suspension but if the suspension is too soft the tires roll over and you lose the traction you've gained. Or if the soft shocks allow the tires to bounce too much, again you lose the traction that you've gained.

Or if one end of the car is so stiff that it lifts the inside wheel off the ground, it cannot take any more load off the soft end of the car.

A soft car will give you lots of traction but then the car will have slow response. A stiffer car will have very fast reactions but have less traction. (well, it would if it was possible to have a car with perfect geometry)

ed

I believe he was stating results from tests, not how race cars should be built.

Don't these comments contradict each other? bars reduce roll which has zilch to do with weight xfer, yet stiffer bars create greater weight xfer :scratch:

Exactly. If grip increased at a 1:1 ratio with load we would absolutely never have to concern ourselves with weight transfer. If it were a 1:1 ratio we wouldn't worry about weight transfering across the chassis in a corner because as the inside tire lost grip the outside tire would gain the amount of grip lost from the inside and the total sum would still be equal. It doesn't work that way. As weight transfers across the chassis the sum of the tires' grip is less than when each tire is equally loaded. This is fundamental. Anything you can do to reduce weight transfer will increase total grip.

As weight transfers across the chassis the outside tire becomes more highly loaded, its cF goes down and that tire saturates and slides more quickly. If we could keep the weight equally balanced at all the tires all the time then no single tire would saturate before the other and the vehicle would experience the greatest amount of grip possible from those tires since each one would be loaded as little as possible. That means the CG as close to the road as possible and the track as wide as possible. Nothing else will effect the amount of weight transfer.

If any test shows "that in order to get max tire grip, you want to allow the car to roll over onto the outside tires and increase the tire to ground contact force" as he said in his post that test is completely wrong. Read any book about suspensions.

Sorry, they do contradict. I should have said stiffer bars create greater load transfer, not greater weight transfer. Let me see if I can explain this without screwing up. There are two things going on here: weight and load. Weight shifts around because the CG of the chassis is heaving around. This shifts weight around the different tires. The swaybar on the other hand is merely a spring. There's nothing it can do to physically move the CG or weight around on the car, it can however change the load the tire sees by making its spring rate stiffer. Since the spring rate goes up that tire must now handle a greater load than it would with a lesser rate.

It does seem confusing but consider a car resting on scales. We can't change the weight of the car or the weight distribution of the car by monkeying with the springs. You can't actually move weight in the chassis without unbolting it and putting it somewhere else. Changing the spring perches isn't moving any weight around the car at all, it's merely balancing the loads on the tires. It seems contradictory because you look at the corner scales and see the numbers change but you have to look at the car as an entity. If springs really had an effect on weight putting softer springs on a car would make it weigh less! They of course don't do that, but they do decrease the loads on the tires.

The same is true of downforce. If we could put scales under the tires as the car traveled we'd see the scales read higher and higher weights as speed increased due to downforce on the car. In truth the car is not any heavier, it is merely exerting greater load on the tires. If you merely looked at the number on the scales you'd insist the car was heavier just because it was going fast, but in fact it weighs just the same it did standing still!

this is the way I always viewed it...

thanks for clearing up the weight/load term. If you read axr6's comments with load in instead of weight...they agree with your statements.

Do you know if the R1/2 front sway bar is identical to the base? If so, happen to know the diameter? ;) that way I won't have to wait until my car is out of paint to measure and order some bushings.

IIRC correctly all the front bars are the same. Rear bars varied among model years but not trim levels. I believe for a given year the rear bars are the same regardless of base, touring, R1, R2 etc but there were different rear bar rates between the 93, 94 and 95 years. The 93 had the stiffest rear bar. The 94 and 95 have softer rear bars but I'm not sure if they were the same.

Double check all of that. The only thing off the top of my head I'm 100% certain of is that the 93's had the stiffest rear bars.

I believe that to be true as you put it, particularly when you introduce CG into the picture. The ideal grip is the one divided amongst four equally loaded flat tire patches. Yet, as shown by the change of a rear bar on the FD (or any car) by increasing the rear roll stiffness we are also reducing the sum of rear tire grip, even though the apparent loading of the tires, side-to-side, appear to be more equal. From all I've learned I still tend to agree with edmcguirk, below, when it comes to dynamic weight and load transfers. I believe that he is referring to softer suspension as softer springs AND bars. (correct me if I am wrong in my assumption)

Actually the ideal weight distribution for race cars (to me) is more biased towards the rear, to provide better accleration traction by placing weight on the accelerated wheels, as well as providing less dive under braking, again for having a rear weight bias.


Those two statements appear to contradict each other. With less roll stiffness the weight and the CG will be heaving around during cornering shifting weight onto the outside tires. I'd have very little doubt in my mind that a softly suspended car, if run on a set of weight scales, heaving its body and CG over the outside wheels, would show a marked increase in tire-to-pavement contact pressures on the outside tires.

Yes, I have been suggested such many times during my racing years. I have no problem with the concept. Yet, having said that what would be your fix for this understeer scenario if not an increase in the rear bar stiffness? Assuming that the front bar is the correct size and reducing it is really not a good option as you'd get more roll. Is there anyone out there succesfully racing and FD with the stock rear bar? I'd find that difficult to imagine.

Actually you are, at least partially, correct on this one. I was thinking back my racing years watching all those stock classes and seeing some of those sedans with huge body rolls with one tire dangling off the ground. Some of those cars have so much spring/shock travel that they lean over alarmingly while do not seem to go down on their bumpstops before lifting off their inside tires. Remember the Citroen CV? I have seen some GT spec cars lifting inside tires but, when equipped with very stiff bars. I always believed that to be a chassis problem, allowing diagonal flex.

I did say, myself, that it was all about balance. I simply cautioned not to arbitrarily stiffen up shocks to do someting that they were not designed for (the primary function of a shock is not for tuning out moderate to heavy understeer) and something that could bite one under certain conditions.

Weight transfer is completely independent of roll stiffness. The equation for Lateral Weight Transfer is:

Weight transfer= G*CG height/track width

Where
G = cornering G
CG = center of gravity

Note that no where in that equation is there anything about springs, bars, shocks, suspension travel etc. They have no effect on the amount of weight transfer.

So far all we know is what the original poster said: "Ok, so I just got adjustable shocks.

If I want to decrease understeer, should I make the rear stiffer than the front, or the front stiffer than the rear?"

Without knowing more about the setup other than he has adjustable shocks and when exactly in the corner the car is pushing no well informed advice can be offered. However no race engineer's first decision is going to be to attack the end that is working rather than the one that isn't. If I walked up him that day and tried to fix it? Absolute first thing I'd want to know is tire pressure and temp.

Depends on what you call successful and what you consider the correct size. I know of many fast FD's with stock rear bars and larger front bars that have no understeer problems whatsoever (mine included).

If an inside tire lifts it will first happen at the end of the car with the most lateral load transfer, that means the end with the more roll resistance. On the vast majority of cars the non-driven end is setup with less lateral load transfer than the driven end so that the drive wheels can put power down as well as possible. If you can't put power down you can't accelerate. That means front wheel drive cars tend to pickup the inside rear tire (especially under braking) and rear wheel drive cars tend to pickup the inside front (especially under acceleration). 90% of the time when a tire lifts in a corner it's not because the suspension has run out of droop and pulls the tire from the ground, it's because the bar is stiff enough and the grip on the outside tire great enough that the bar overwhelms the spring on the inner tire and pull that tire up from droop.

2CV's are strange beasts in that their front and rear suspensions are interconnected. Even though they are raced overseas I've never heard anyone use "2CV" and "handling" in the same sentence :p: They either make it around the corner or they don't ;)

Anyone running shocks with multiple adjustments disagrees with you. The entire point of developing 2, 3 and 4 way shocks was to isolate slow speed adjustments (chassis management) from high speed adjustments (surface irregularities). Shock adjustments are exactly for tuning such things as understeer.

DamonB says "Without knowing more about the setup other than he has adjustable shocks and when exactly in the corner the car is pushing no well informed advice can be offered."

I can't believe it took this long to get to this statement. While there has been a ton of great info thrown around this is the first thing we need to know to realy help.
General statements here, and it will depend on if you can change rebound independent of compression.

If it is pushing when you first turn in soften the compression in front or stiffen rebound in rear.

If it pushing as you exit soften rebound in front, stiffen compression in rear.

If its pushing in the middle its not your shocks that are the problem.

Don't add so much rebound that you smash the chassis on to the bumpstops after a few laps.

The ability to adjust things independently is why people spend $5-10K on shocks.

You purposely restricted your question to adjusting shocks to decrease understeer and I understand that if there is only one device that is easily adjustable then that is the one you want to adjust (when you have a hammer everything looks like a nail) but there is often another thing that is easily adjustable - the nut behind the wheel.

When I increased the boost on my autocross car by 30 HP, suddenly I had an understeering problem. It turned out that my increased speeds were causing me to go just a little bit too deep into every corner. I had to use the brakes too much and the front end washed out.

I entered the corners a little less aggressively and suddenly the oversteer that I knew my car was capable of was there in abundance.

Step back and examine your driving style. Adjustable shocks on an otherwise stock car can change the flavor of your handeling a bit but the driving style can have a major difference.

ed

DamonB -

I have read and learned a lot from your posts in the archives since I'd joined this club only a few months back and I do have a lot of respect for your knowledge.

I think that we have some differences of opinion regarding proper car setup. That is fine, as there are more than one ways to skin a cat. I assume that you are a successful racer and an engineer as well.

I have had my share of racing success, winning a title in autocrossing going back to 1984 and racing in NASA Pro7, SCCA GT, FM and FS classes, winning probably close to 50 SCCA road race events, including 3 Regional titles and one West Coast Road Racing Champ title. During that process I built much of my race cars and set up the suspension, did my alignments, etc…, as well. I must admit that I ran on a shoestring budget, financing my racing through the pay of an Electrical Engineer, so I never had the experience to use some of those very expensive Penske style shocks that you seem to be referring to.

The advice I had given to the poster was reflecting my experience and my successes. I would begin setting up a race car with the initial establishing of a basic balance front to back, selecting the best combinations of spring rates, ride heights and sway bar rates. I did a fair amount of track component testing but, nowhere near enough (budget) to feel confident for having the “best” possible setup. (Is there such a thing?) It probably would have been a waste of my money to even purchase those multi adjustable shocks as, witnessing some better financed National or Pro teams, they had spent way more time and money on testing shocks only than my total testing expenses for the whole car. So, I would just ask some experts on shocks to advise me on my selection (reasonably priced) as to their suitability to my spring rates.

Once a basic desired handling was established with the above tools, I simply used tire pressures and the shocks to fine tune that handling to the track conditions.

Having sad that to introduce myself, now I agree with you and other posters here that we've gone too far in advising the original poster. He told us he had adjustable shocks and asked us what to do with it to reduce understeer. Now, we're at the point of suggesting entirely race specific issues such as tire temperatures and multi stage shocks tuning ,which in itself is a small science. In all likeliness these issues are entirely not relevant to the original question but, would make a great educational discussion for racers only.

I also used to race my 1993 R1 FD rather successfully back in 94 and 95. I quit racing street cars on road race tracks when I put it into the barrier in Turn 7 at Sears Point. One could argue that it was because I used a much stiffer than standard rear sway bar for it, for the car did spin on exiting the hairpin under power. Yet, in my tested experience the adjustable rear bar gave me considerably better balance and reduced lap times. It was a matter of a minor mistake in a very neutral handling car when I was unwilling to give up a fraction of a second to back off at the fist signs of a loose rear end, for not wanting to miss what was shaping up to be the fastest lap of the race, over some very respectable competition.

My second, recently purchased FD, a 1993 touring version, also came to me with stock suspension. After replacing the springs with rates of 430-325 F-R, I had, once again, found way too much understeer to my liking. So, I put on a much higher rate rear bar and for the street driving that I intend to do, this is close enough for me. The car is a joy to whip around medium to fast corners. I would love to go back to tubular bars with aluminum arms to save weight and give me more range but, it is not worth the cost for the present use. I will put on a set of Illuminas to give me some adjustability and, hope to find a setting that will keep that car glued to these horribly bumpy CA mountain roads. No more racing in my future, simply pleasure driving.

I am sure, you also recognize that different people select different solutions to make their cars handle well. My suggestions reflect my knowledge and the solutions that appeared to work for me over the years. The great thing (and also the great confusion) with a forum like this, that a poster can receive contradicting advices to his/her questions and just have to walk the line and do the homework with all that info to make the best possible decisions that fit a particular car setup, driving style, budget.. etc. I’ve been there and, I suspect, you have too.

Best Regards

Albert

^ Albert I don't doubt at all that you're fast and it sounds like you certainly have more driving and building experience than I do. The problem we all run into however is in using words to describe something animate like driving or setting up a car. When that happens we must be certain that our language is correct or our the facts we present end up being wrong. I have no ill wishes at all toward you.

I'll be the first to agree with you that in amateur racing you don't need money to be fast (or have fun!), but it always helps ;) If the guy with more money still can't drive what he's got then his money won't help him. My car is a consistent underdog against the competition and that always leaves me with a convenient excuse. I hate that. At the same time it's an absolute joy to get behind the wheel of the FD and drive or compete, even if my competitors are beating me. I considered buying a different car to try and prove to myself how I really rate among established top drivers but it came down to me deciding my ego shouldn't be out spending money. If I had a lot more money I'd do it though ;)

Totally correct...

Dont' forget camber, too. Oh, and corner weights, physical weight distribution... :D

Mmmmm brain food thread. :)

This may not be 100% technically accurate, but this is the way I reconcile the physics of it all in my head. The more flex you have in a setup, the more it will absorb the cornering action.

Like these extreme situations, with no sway bar in the rear, the strut towers and wheels will flex independently depending on the force applied to them, absorbing the tendency of the rear end to come around. The struts will compress individually to the best height to absorb the momentum, and the body will roll (because the outside strut will compress more, and the inside one will actually want to climb). Between the 'damping' force of the struts (or dampers, if you prefer), the springs compressing, and the sidewall compressing and tread of the tire in friction with the road, the car will fight the cornering forces. So relatively speaking, the softer end of the car will hold the road better. If your whole car is too soft, cornering will feel mushy and unresponsive, the car will tend to understeer, and body roll will be very uncomfortable.

Whereas if you took the struts and springs off the rear completely and bolted everything together solidly, connected both struts with a swaybar, and put so much air in the tires that the sidewall wouldn't compress at all, then whenever you corner, the only thing fighting the cornering forces is the tread of the tire on the road. And most likely, if you have enough pressure in there to keep the sidewall from compressing, then your contact patch is only going to be on the center of your tire's tread anyway. Now when you corner, there's almost nothing fighting the cornering action. So now, relatively speaking, the stiffer end will break free of the road first. If your whole car is too hard, you'll turn fast and have no grip, so you'll most likely end up spinning down the track if you ever get going, and initially won't be able to keep the car pointed in the right direction.

Obviously, these are extremes for illustration purposes, and the right answer is somewhere in the middle. FWD cars will inherently understeer because of the nature of the drivetrain, and RWD and Midengine cars will inherently oversteer for the same reason. AWD cars will do either or both depending on the gearing and power/torque relationship between the differentials, and on some cars it's easily tunable, which is great, except it also adds 300-600 lbs depending on the setup.

Ideally you want the back end to break free first, but at a manageable rate so you don't go wildly out of control when it leaves on you. Which means stiffer than the front.

So to decrease understeer/increase oversteer, alter any of the things that affect stiffness, you'll obviously want softer/less in the front and stiffer/more in the back, so - (this assumes the car is otherwise setup correctly)

less tire pressure in the front, more in the back making the sidewall more or less compressible (Carroll Smith had a term for this, like dynamic stiffness or something in Drive to Win)

stiffer springs in the back or softer in the front

more(stiffer) bar in the back, less(softer) bar in the front

more damping on the struts in the back, less in the front

- With that said, experimentation (safely!) is key, because stiffening the rear of your car using tire pressures is going to feel different than stiffening the rear of your using sway bar, which is going to feel different than higher rate springs. Also keep other things in mind, like body roll which is a whole car thing. If the car leans a lot when you go into a turn, you need bigger bars or stiffer springs or both in the front AND back, and THEN adjust the ratios between them for more or less steering.

More maneuverability makes for better times, to the extent you can keep up. Like fighter jets for example. They're set up so dynamically unstable that the computer has to make thousands of tiny corrections every minute to keep it from spinning out of control. The pilot just suggests to the computer which way he wants the plane to go and the computer does it. If you set your car up to be dynamically unstable to that degree, it will turn great, but it won't help if you can't keep up with it.

Also, I second Damon's post about don't mess up the good end of the car trying to fix the bad end. If your body roll is taken care of, and the only problem is that the car pushes when steering, soften the front of the car. If you find then that you've induced body roll again, then solve THAT problem by stiffening the whole car.

I know this is an old thread, but I hope this helps someone!

You have the "how" right but you have the "why" wrong. Phrases like "The struts will compress individually to the best height to absorb the momentum" and "the car will fight the cornering forces" don't actually mean anything even though they sound good.

I don't think I would say that you are wrong but your descriptions don't describe the phisical world in a way that could be extrapolated into other facets of driving and traction. If you have the basics down correct but you try to extrapolate your reasoning into weight distributions or driving styles you might come up with completely wrong answers.

You sound like you have the intuitive underlying reasoning correct but your descriptions of those reasons are not factually correct. (at least it is better than the other guys who are wrong and their explanations are the opposite of reality)

ed

That's right, I never actually finished my thought on the part about the struts compressing individually. :P I had intended to move into how the sway bar helps the body stay flatter on cornering by forcing both struts to move together (to a degree) instead of allowing them to operate fully independently. (Where one may compress and the other extend.) :P

But yeah, like I said in my disclaimer, this probably isn't 100% accurate, but it's how I make sense of it in my mind. To be fair, the guy I learned all this from didn't know a damn thing (I'm self taught) :D

Tune to Win is probably a better source of information than I could ever be, but I haven't made it to that one yet. Although I read Prepare to Win and it wasn't a great deal of help, unless I someday decide to construct my own race car. :P

Under Steer WHEN???
 

At what phase of the cornering do you have the under steer problem? Is it entry, middle, exit? Is it on a slow corners or high speed corner what rate of speed are you traveling? What type of car and weight is it? What type of tire compound and pressures do you operate? Is your steering input slow, moderate or fast? I can not see any one providing any information except general bits to try and help. Provide more information then people can help. Also if you can maybe refer to a race track and a particular corner could help.

Run Hard and Race Safe.