Sorry this is going to be long, but please read!
Ok this is my first full year of autocrossing and I have been trying many things. I started with a pretty stock GSR and I quickly found my suspension to be rather weak and holding me back. I then added Ground Controls(Stock rates) and koni yellows. I played with this for a couple autocrosses, but my beat 712's couldn't handle the suspension. So instead of not overdriving the car so bad, I buy a set of used Hoosier's and rims from MAX for a song. I didn't anticipate buying them but they were too good to pass up. Which brings me to today. So its raining and cold and I am going to run R compounds for the first time.(stupid) Anyways, The first run I go very slow and get an idea of the track. Second run I spin out I check my tires and the sidewall is not flexing at all. I started with 44PSI front/Back and have my konis set to 1.5turns Rear and 1 in the front. Third run I am faster and getting more comfortable. Fourth run I spin again. Note: All spins are from too much oversteer. The fifth run I turned the lonis down to .75Front and 1 rear and proceed to spin again and this time do cosmetic damage to my car and almost doing structural damage.. I am very frusturated and plain embarrased. I am still learning and I have a lot of variables to factor in, but I am very frustruated....

Throughout the afternoon I continually talked to many people and they all said I was running too high psi in the tires. The last run of the day I was down to 33psi F/B. Is it just the driver or the car? I think its the driver, but I am on new to R compounds and still working on the car... What to do? Can anyone lead me in any direction?
Today I needed to check my ego at the door and its been severly bruised... Am I the only one this happens to? Hope you guys can help! Thanks!


[Modified by VTECAcuraGSR, 2:56 PM 9/15/2002]

 

Uhh.. how hard is it raining?

When I ran my nearly bald R tires in a downpour this summer, the car would be STICK, then hydroplane, STICK, then hydroplane...

It made for a... ummm... interesting run.

Have you considered changing the pressures on the rears only?

 

It was not raining hard just enough to keep portions of the track wet and the other parts dry. I considered changing the rear pressures, but I thought my suspenion changes would have eliminated the oversteer....

 

The tires are part of your suspension... the most important part. You can change behavior a lot by screwing with the pressures.

However, I would try running the shocks stiffer up front before changing the tire pressures. Ideally, the tire pressures are the LAST link in the chain in suspension tuning.

I assume, by "stock" spring rates, you mean ~225 in the front and ~170 in the rear?

 

Sounds like you had WAY too much air pressure in your tires. They probably felt really squirmish. I run A032R's on the road course at a 28-29 cold in all 4 corners. I shoot for 39-40 HOT. If you were running 44 cold then you are way out of the range i would think.

I know Auto-X doesn't get as much heat in the tire as road courses do so i would try to find a happy medium and start out at like 34 in all 4 corners. Once you feel comfortable enough then go higher in the back for a bit more oversteer. Play with the pressures but i can tell you that 44psi is HIGH. What is the max PSI on those tires BTW?

mike

 

Actually the stock ground control rates are 350F/250R.

As far as pressures I was starting at 44psi because I was follwoing others advice... See link https://honda-tech.com/zerothread?&i...612113#2612113

I also need to really get used to having no notice when the tires break loose... There was absolutely no warning.

 

Now you understand why several of us recommend running on streets for a season. After a while, I stopped hearing the street tires squealing, I started depending on feel.

When I run in the rain (which I love doing, esp. on street tires), my car is much looser than dry... it might just be the slick track.

Andy - who would also have bought used Hoosiers for a song...

 

Aren't Hoosiers supposed to basically be junk in any sort of rain more substantial than damp pavement? And further junk in cold temperatures? You're not really gonna get much temperature into them anyways, and any temperature you DO manage to get will be at the front end, making it stick better than the rear. I'm pretty sure Hoosiers won't be of much use in cold, wet conditions where they don't get the temperature to make the compound grippy, and even new Hoosiers have holographic water evacuation channels. Used ones probably have none. Even in AcuraRacer112's car on stock tires in the rain, I didn't get a whole lot of warning from them when they started to slide. I just sortof anticipated the slides with what I was doing with the car. I was responsible for setting his car up with too much air pressure, it didn't grip like it should have, and the front end basically skated around every turn.

 

Am I way off on what I should use for koni settings?

 

I'd have probably tried running the back shocks 1/4 to 1/2 turn softer than the fronts if you were having that much of an oversteer problem.

 

if it's your first year, try to set the car up for a bit of understeer, or possibly neutral, and work towards oversteer. Those pressures sound pretty high, especially in the wet (loose 3-5 PSI for rain compared to your dry settings). Street tires are more forgiving and communicative, I don't blame you for jumping on race tires at a good price, but they can let go very fast if you're not used to the signs that they're slipping, and since they're so quiet the primary warning isn't there. Keep at it, you've made the most dramatic change you can make, and it's going to take a few weekends to get used to it and get things nailed down.

Aleph, who had a blast today slippin and slidin on the soaked beaverun lot on P7000s, and who was equally pleased that he was lazy and didn't have to change tires in the rain

 

Where should I start for tire pressures next time?

 

on that thread, only two comments were really germane, one who calls 40 psi the high mark and tells you to go down from there, and another who's running 54 (!?!) and advising 44.. From what I've heard of the Hoosiers, and race tires in general, the stiffer sidewall allows lower pressures than street tires. Since I'm running my street tires up around 45, I would have to go with the "sub 40 psi" advice as being more inline with expectations..

The one central theme was "just high enough to avoid rollover", so I'd keep dropping the pressures and checking until rollover, and then bump them back up a bit..

Disclaimer: I don't own and never have owned race tires.

As for shock tuning, Sports Car Magazine's shock tuning guide seemed to be along the lines of "stiff out back for to reduce understeer and help sweepers" and "stiff up front for good transitions and to help slaloms".. so I'd soften the rear relative to the front if spinning is a problem that you want to try to address with shock tuning.

 

first, don't let one bad day frustrate you, we all have them some more interesting then others. when i started autoxing i was told not to put money in to the car but the driver. iit's hard to resist adding parts to your car, but i have been running a stock jetta in sts and have been competitive. good luck and keep trying

 

Please keep the suggestions coming! Does anyone have a similar setup? What I have is pretty common, I was wondering what others are doing...

 

on my hoosier combo i run 35-36 in the front, 40-45 in the back starting/hot pressure. i do not run these when it wet at all. on my kumho combo in the dry i run 40 front 44-46 in the back. yesterday it rained, and i started at 39front/39 rear with the kumho's. it dried up a bit, and i was back to my dry pressures, and ran my fastest time even though it started to rain a bit. i don;t know if this helped or confused you..............

 

Few notes here.....

Tire pressure
Someone posted up above about taking pressures down in the rain, this is good advice. You are supposed to keep the pressure in your tires just high enough that you don't roll the sidewall. Also mentioned was that the R-compounds have a much stiffer sidewall (true) so you can run lower pressures without too much problem. However, this depends somewhat on the tire size, rims, suspension travel, etc. I run my kumho's around 36-38lbs cold in the front and 30-36lbs cold in the rear. You can mark the sidewalls with chalk (no shoe polish here) and see if you are smudging it during your runs, if you arethe pressure is too low. The whole point of this dance is to vary the stick front and rear of your car. Higher pressures in the tires tend to stick less than lower pressures when compared on a same speed, same radius turn. As speeds go up, you need the extra pressure to prevent rollover but it't at the cost of some grip. I would suggest that you find a nice comfortable front tire pressure (for me that's 38 on a fast course and 34-36 on a slow one) and then I vary the rear pressure to either get oversteer or understeer. Keep in mind with these pressures that I'm in a CRX, got a GSR

Shocks
The rebound control on your shocks should primarily be matched to the spring rate of your GC's and then given a bit of a nudge based on your preference. This means that the car should not feel bouncy after the intial bump (on a road dip or something) but should not be soo tight that you get into a lockdown condition and end up on your bumpstops. You can also tweak the rebound control to let a wheel back down earlier from a bump rebound, by bringing a specific wheel (or set of wheels) back in contact sooner you increase the pressure on that tire and can cause it to break sooner than another tire. in english, if you loosen up the rear rebound it causes oversteer.

Driver
lastly, and I should have put this first. Take a serious look at how you are driving. The R compounds are going to make every input you give the car much more apparent. You said that all of your spins were due to oversteer, my first thought was throttle lift. If you let off going into a corner the deceleration of your car transfers weight forwards, giving the front wheels more traction and the rear less. This, combined with turning will automatically bring the rear end of the car around. Try to keep everything smooth, both going on and coming off the throttle. The water you had (especially since it was patchy) just makes any jerky movements that much worse as you have an even smaller traction budget to work with.

R compounds are a blast, you'll have a grin on your face ear to ear when it all comes together.

Ian
89 CSP CRX Si

 

FYI, I am running Kosei K1 15x7 with 205/50/15 Hoosiers.

Even at 33psi I wasn't using all of the tire, I still had more to use. But speeds were not tht high sence it was raining. If I want to reduce oversteer shouldn't I reduce
the psi in the rear?

Also with the shock settings, I had a good amount of oversteer with 1turnR/.75front. I could continue to reduce the oversteer by putting the rear down to .75. Right?

On a final note, with my strret tires I knew where the limit was and I learned to keep my foot in it when slidding. I believe I did the same last time, but it was snapping around too quickly to catch. Does this make sense?

Please keep the help coming!

 

Yah, the rain keeps speed down a bunch (at least in the turns), which is why it's ok to run the lower pressures (lower speed = less rollover). You are correct, to tune out oversteer reduce PSI in the rear. The reduced pressure gives greater grip in the rear, helping to keep it in line.

As for the shocks, if I recall correctly, turning to the right tightens the koni's so you would want to go up in the turn amount in the rear to reduce oversteer. I run all 4 of mine between 1/2 and 1 turn back from full lock. The extra damping force helps keep the car stable in transitions as I don't have that big a spring or sway bar rate. Try cranking yours all the way over and backing off 1 turn on each shock. Drive it a bit and make sure you are not locking down into your bumpstops. Adjust from there....

It's good you are keeping your foot in. It may just be you need to let off a bit easier on the throttle as everything is more sensitive. Or it may just have been the spot you were at in the course called for a different approach to the turn. The other thing is the snap will be more pronounced if you were sliding in from another turn. Say you are slipping around a right hand sweeper, keeping the throttle down with the rear of the car slipping out. Now say you come up on a left turn, you let off a bit as you need to brake (lightly, very lightly now) but turn in to the left to keep straight and line up for the left turn. When you go back on the throttle weight goes back and all of a sudden you have pressure on your rear tires. Since straight ahead for your rear tires is still pointing to the right they will snap the rear end of the car that way (you are still turning left here) and all of a sudden you are turning left with the rear end snapping around to the right... and viola you are backwards.

Now, how to not do this again well, the fun way is to not brake quite so much (rear end does not swing left as much, so you stay straighter coming into the turn. Then don't give as much gas coming out and hope you can do a nice snap around the cone and not loose the rear end in the process. The best solution would probably be to late apex the sweeper so you are not slipping in the last part of it. This keeps the car nice and settled in the end so you can brake, shift in a straight line. Then the left turn just becomes a matter of finding the correct speed and line.

The fastest line is not always the one with the quickest corner exit speed. Sometimes it's better to keep a turn slow so you can line up for the next one. or the next one, or the next one, or the....

That help?

Ian

 

It was cold and rainy. Pretend the day did not happen and start next event at 44.

FWIW I have a DS Type R with Hoosiers and run 51 F 47 R on concrete and 47 F 43 R on asphalt (assuming temps around 80 degrees)

Do yourself a favor and go back to street tires. The guy who sold you the tires probably used them up (even if they are not corded they may have too many heat cycles in them) If you refuse to stop changing your setup you won't progress in your learning curve as quickly as you might.

This sport is all about driver skill and has little to do with car setup. You won't develop as a driver if you don't have a stable setup.

Regards,
Alan