I've had an interesting (VERY annoying) suspension tuning problem as of recently. I'm hoping the problem is correctable but if it is not then I may have to look at some autocross events as competitive and then others as just fun events and a chance to go fast.

Overall scenario :
I run with many different clubs at many different lots. Some are smooth, some are not. For those that know the lots : Camden, Englishtown, Meadowlands overflow lot are the smooth lots and Meadowlands lots 17 & 18 are the rough ones. I though I was just having bad days but as it turns out I'm not very competitive at all on the rougher lots and on the smooth lots I'm very competitive. Cars that I would beat by 1-2 seconds will beat me by 1-2 seconds. The last two times on these rough lots I've driven someone else's car and was able to generate respectable times. In the case with last event I had someone else (thanks Chris) drive my car and he encountered the same problem I'm having.

The Problem :
Usually, with setup listed below, the car has strong tendency to oversteer. First runs on cold tires are definitely in the snap spin territory if care is not taken. On these different lots which have some cracked pavement and rolling dips and rises the car has what I refer to as a "Terminal Understeer" (I want to kill myself its SOOOOO bad). Under straight line braking the tires will grip then slide (skitter?). Stopping distances become very long. In turns, abrupt lifting/braking, make the car plow. Going to fast… makes the car plow. The back end has MASSIVE amounts of grip while the front end has none. I tried reducing my front shocks to full soft (though this rebound only) and dropping 6-8 pounds from the front tires. The front would not hook up.

I drove two events back to back this past weekend. Saturday at Englishtown (smooth) and I had no problem being pretty high in both PAX and Raw times. Sunday at the meadowlands lot 18 (rough) I got trounced by a lot of cars (quite a few were even running street tires). Between the two days it felt like I was driving two completely different cars. (did someone secretly switch them?)

My Ideas :
-Shock compression is too stiff for this pavement?
-Spring rates too high for this pavement?
-Wheel rates? Don't know much about this…
-Small wheels/tires? I don't know why this would effect anything but this is a major difference between me and other cars.

Setup :
2000 Integra GS-R
Koni single adjustables
Ground control coilovers. Rates Front : 525 Rear : 400
22mm Rear swaybar.
Upper front strut tower bar
Quaife LSD
225/45/13 Hoosiers on Panasport 13x8.5 wheels

Any help would be GREATLY appreciated! I've never been at such a loss to correct a problem. Drastic tire and shock changes had no effect on the car.

 

A couple of suggestions.


1. Before you change anything, have a very experienced driver do a few laps in your car and make sure it's not your driving techinque causing the problems. This is the easiest and cheapest double check.

2. Are you running a front sway bar? If not, put the stock one back in and swap your front and rear springs.

3. Is your car REALLY LOW? Cars that are too low tend to bottom out the suspension during cornering causing the spring rate to go infinate. This can cause wicked oversteer or understeer depending on which shocks bottom out first. (This would also explain why you do well on smooth ground rather than rough.)

 

Matt,

First off, I hope you are not trying to tune the car based on that pit side lot at E-town. Do yourself a favor and forget about tuning there. The lot is very slippery in the morning and "wierd" in the afternoon. The places you'd "think" it would stick, it wont and places you'd think there is no possible grip, there is.

I watched a few of your runs and really wasn't bad at all. With the LSD in the car, "drag" the rear around instead of trailbraking, get off the center pedal and feed in the right one. The tires will hold and the rear will follow.

Camden however is a very good tuning lot. It's relatively flat, sticky and usually consistent from AM to PM. As far as setup goes, start from here:
Set the rear shocks full stiff, front shocks half stiff. Front pressure 2-3psi higher than rears and tune the car with tire pressure. Don't change anything else except tire pressure for an entire event and see what it does to the car. Depending on what the car did with the changes (Terminal Understeer or Oversteer) THEN adjust the shocks (go stiffer or Softer in the front, leave the rear full stiff). Generally I found on the Del sol (with LSD and full GC kit ERS springs and ITR rear bar) was that the HIGHER the front pressure went, the LESS the car would understeer. I settled on 38 up front (on 205/50/15) Kuhmos with the rears at 34-35. Shocks were set at half up front and full in the rear. Brake early and accelerate out (slow in fast out) The LSD will help you track out a good line but you need to be on the power for the "drag around" effect to work, if you are coasting, it WILL spin...
Also, left foot braking helps and you can feed the power in without a full lift, this will help keep the car settled, also a quick stab of the left foot will transfer weight up front and give a quick steering input and right back on the gas. I use this for a pivot cone in a faster section where I want to keep the speed up, but NEED the car to turn. ( At E-town last weekend, I used this to get around the right hander after the left after the start) was just enough to turn the car and STAY on the gas...

If you are talking about snap spin oversteer after the above mention right, the pavement is off camber and sandy, Same condition also present at that hairpin (both at the PCA event and the NNJR events). Into the hairpin, there was VERY LITTLE grip under braking and even less after the apex. Needed to be slow and tight and hope you had enough HP to get going again. I for one, did not...

Look at the NNJR Results page. When FM can PAX an event, you know the course is loose and slippery. I watched dozens and dozens of people run wide there trying to "carry speed". You couldn't.. That was one case of slow is slow and if you got on the right line to the first slalom cone (apex left hander) you could tap the brakes, tap again at the 3rd/last cone and flat out until the 2nd cone 2nd slalom) and accelerate through the finish... I was kinda able to do this in the DSP Neon I instructed in, but the inside wheel spin prevented the car from turning under acceleration into the finish, thus resulting in a "tweener" (Cone right 'tween the headlights).

Hope this helps, where are you running next??

Jeff
[edit for what else......spelling]


[Modified by jasyatz, 7:35 PM 7/22/2002]

 

Matt, Jeff is right about the course at etown last Sat. there are a lot of sand in the morning but I guess you guys clean it up quit a bit in the morning runs and the runs I have aren't that bad. I use to have snap oversteering problem like you in the beginning of last season. I found out its cause by the toe out in the rear tires, the car became much more stable after I dial the rear toe back to 0. I'm not sure if this is the same case as yours but you can try it out.

Kev

 

Actually the snap oversteer is NOT the problem I want to eliminate. I was very happy with my runs at e-town. Everything you guys said just reinforce what I felt about the course. I understand its slippery, that I can handle as long as I can plant the front (which I could) and have a relative decent amount of grip in the car (which was also true). The problem I had was with sunday at giants stadium where the front of the car would not plant (it had about 1/8th to a 1/4 of the traction I had on saturday at e-town whilke the back suffered no loss in traction at all).

Steve91 : Thanks for your input...
1. I had Chris Shenefield (very respected driver) drive my car on sunday at the same event and he was having the same problems I was having. I drove his car and I didn't have the problem anymore....
2. Stock front swaybar.
3. The car isn't really that low. By no means is it "Slammed". I think its lowered about an 1.5 inches from stock. Interesting idea that I may be bottoming out the front shocks though.... explains the why they would grab then slip.... grabs great then the shock bottoms out and the wheels slip. the shock decompresses grabs again then bumps... repeat as needed....

Jeff :
I'm acutally off for 2 weeks (social crapola). then I'm going to divisionals at Ayer, Mass. I'm not too worried cause I hear Ayer is very smooth. then its every event I can hit before topeka! I really didn't have any complaints about the pit side except that its not as nice as the other side! Camden is fine. Nazareth is fine... Rome & Peru were fine... just damn giants stadium... Gotta check the shocks.... could be the problem.

Thanks for all the info guys... anything else I might want to check?


[Modified by Watkinsm3, 8:40 AM 7/23/2002]

 

Black turbo civic hatch right?

Actually I've adding toe out in the back to add more rotation... The car is almost perfect (for me) at e-town... The snap spin is just a concern for over aggresive first runs on cold tires... its not a problem after the first run.

 

Matt, your Hoosiers may be going away on you. This sounds like the symptoms of Hoosiers reaching the end of their life. They will begine to degrade quickly in their performance at the end. So all of a sudden at an event the car will just not want to turn in.

 

hmmm.... Somone else suggested that on sunday. Then I told them that I bought them the week before the Peru Tour (1st or 2nd of july) and scuffed them in at the practice session on that friday (the 5th). The person just shrugged and wished me luck solving the problem! they should still be good...If this was the set I had bought back in april I could see them being old...

Thanks for the idea though Eric...
Weren't you supposed to come out to Peru and play?

 

have you been rotating them front and back at each event to ensure the wear is even?

And you did run them at Peru with is concrete and tends to burn up tires pretty quickly. If you have done Peru and 4-5 events since then, I would be willing to bet it is your tires going away. I would talk to Mike Neary about this. He has a much better idea on the wear of the Hooisers on the teg's.

Yes we were suppose to be at Peru, but were unable to make it at the last minute. Oh well. the Pro finale and Nationals are it for the rest of our season on the national level.

 

I talked to mike earlier this morning... He was saying that he encountered a similar problem on... hold on... checkin e-mail...
<U>MIKE NEARY :</U>
I'm not 100% sure I subscribe to his beliefs (at least with my car ) I still havn't checked my shocks yet (damn I'm lazy) but it is my guess they may be bottoming out. This past sunday was only my third event since Peru on the tires. I really hope they're not done. I wanted to make until a couple events before topeka.

Are you going to run the subaru in DSP at topeka?

 

Mike is right, if the sureface is real rough stiff cars have a tough time hooking up. especialy with the heavier front springs set up you are running. If you were hitting the bumpstops during turns, the car would turn in initially, then when it reached the stops, it would start to push. It would do this unless you are riding on the bumpstops all the time. It sounds more like you do not have initial bite.

How are your tires wearing? are they wearing evenly across the tire? if they are wearing significantly on the inside, then you have too much neg. camber. Mike has had a problem with this and has ended up raising the car come more to reduce the neg camber. with the double wishbone front on the teg, it needs much less neg camber than cars with struts. Only need a little more than 1 degree of neg. borrow a pyrometer from someone and take some readings on the car. It will help turn in as well if you are using all your tire. hehehe. So my real suggestion, before you go changing parts, make sure you are actually using all of your current setup.

We are running STS at the Pro Finale and Nationals. DSP was going to be a one shot trial in Peru.


[Modified by Crosser, 8:15 AM 7/24/2002]

 

Matt, yeah I'm the one that drives the turbo civic. I read your problems again and I'm glad that you brought this up because I have the same problem as you do. I compare my runs at both Etown (smooth) and Nassau Coliseum (rough) Last weekend. I too have a heavier spring up front than rear. I did really well at etown, the car have plenty of grip through out the course, but I just can't drive it the same way at Nassau which is rough and bumpy. I got snap over steer in the the first turn every run and the car push in every other corner....

 

It certainly sounds like I've got to do some investigation. I'm done autocrossing for a couple weeks so this will be a tricky one to solve. Tires are wearing very well... Like you were saying I run just a little over -1 degree of camber (about -1.2 I think). I used a pyrometer this past sunday and I was definitely warmer on the inside of the tire. about 5 degrees if I remember. I know I should target even temps all the way across...i wish I could us a camber kit in DSP....

Any recomendations for testing to see if the shocks are bottoming out? I guess I can assume if they do it to and from work then it will happen while I'm autocrossing? I guess I'll put a twist tie on for the ride home...

 

Zip-tie method is what was reccommended to me, but you're probably going to have to wait for the next autocross to get them to bottom out since you have some pretty stiff springs, and won't be on hoosiers for the drive home(or will you? ). The other alternative is if you know of a nice big empty lot near you where noone would mind if you tore it up for a while (I'm still looking for one of those near me ).

 

exactly what Mr Brite said. Take a zip tie and wrap it arong your shock shaft and push it down so it is in contact with the outer shock body, so that when the shock shaft slides into the body, the zip tie will will be pushed up the shaft as far as the shaft goes in the body. Wow that sounded pornographic...hahaha. it is the easiest way to tell though. This will have to be done when you are racing to get a true measure.

 

Well, I just thought I'd dredge this topic up from the graveyard. I just received my shocks from Truechoice! So after a late night install either tonight or tomorrow night, I'll head out to Rome, NY for a Test & Tune this saturday! Time to get them dialed in! hopefully this will alleviate the suspension problems that I was experiencing!

Finally they'll get a rough test at the Philly Region event at Nazareth on sunday. If all goes well the car will be back on top and ready for Topeka! Woo-Hoo!!!!!


[Modified by Watkinsm3, 9:06 AM 8/22/2002]

 

I'll have to get a ride with you some time to see how that suspension is.

 

Any time, I'm always interested in outside opinions on the car (besides the opinion that the car has an affinity for cones). Maybe we can even arrange for you to take it for a fun run when I get back from topeka!

EDIT : Just realized something. Don't you go out to pittsburg for school? hmmm.... might have to arrange something sooner.


[Modified by Watkinsm3, 12:32 PM 8/22/2002]