spectacle

I've been on this forum long enough to know that each tech subsection has its own experts who will immediately call out BS when they see it. Even so, I hope this post will not end up turning into a flame fest due to my inexperience in this area. I am a FI/drag race/straight line guy, so I rarely drift (see what I did there) out of those lanes (I did it again). One of my buddies who is a big Auto-X guy invited me to a local autocross and I thought it would be fun to actually turn the steering wheel for once.

Specs on my car:
AP1
Custom turbo kit ~ 400whp+
CR shocks over Espelir springs in front (10-12k on shocks purchased brand new, springs over 30k)
OEM AP1 shocks with Espelir springs in rear (85k on shocks, same 30k on springs)
Front 225/45/17, Rear 245/40/17 Hankook V12 - ~10k on tires all the way around, tons of tread
32 psi checked on all four tires the night before
CE28N wheels, S2k offsets (+50F +63R I believe?)
Hawk HP+ pads in front, OEM stuff in the rear. About 25% life left on the front pads
ATE Superblue fluid

I'm sure if you know about this kind of thing, you'll probably be able to guess how this all ended based upon the bolded. In the interest in full disclosure: my last alignment was done last year. I don't have the numbers but everything was well within spec. Car drives straight but there is a slight vibration at sustained speeds coming from the rear somewhere (might be an axle going out). On the street, the car is really well mannered over bumps and uneven roads, but when you take turns is when whatever is wrong with this setup rears (I'm getting good at this) its ugly head. When I take a fast on/off ramp, if you modulate the throttle just a little you can feel the weight transfer from front to rear. If you let off the throttle, the front unloads and it becomes slightly unsettled. The more abrupt the decel the more exaggerated the weight transfer. Imagine holding 40mph through a turn then backing off the throttle just a tad, like if you had to decelerate to stop from hitting a car in front of you, and feeling the car get unsettled. Not out of control, but unsettled. I know AP1's are supposed to be tail happy and sensitive to changes like that but it was never like that when it was on AP1 shocks all the way around. I replaced the front shocks about 1.5 years ago because they were blown and I figured upgrading to the CR shocks would make the car handle better. Again, I'm a drag racer so please don't judge me.

Now on to the autocross. I turned the boost down as low as it could go to try to keep everything manageable. I had an instructor riding shotgun on all four of my runs. My car did TERRIBLE. I know its the car because I had an instructor drive a lap and at the end he said, and I quote: "don't take this the wrong way, but this is the worst handling car I've ever driven". Please forgive me for not knowing all the correct understeer/oversteer terminology but when I say this thing got loose, I mean it got LOOSE. It felt like I was out there ice skating. You could never tell when the car was going to let go...there was no progressive nature to it. One second it was holding and then next I was rotating around looking in the opposite direction. I knew taking a boosted car out there would be a challenge but the issues I experienced had nothing to do with power. I'm well aware that my bushings could be shot or something might not be preloaded correctly, etc etc. But I truly think the problem is that I mixed shocks with different dampening rates and it really messed up the balance of the car.

I'm posting this as a warning to anyone out there that might be thinking of doing something similar. I'm looking into BC coilovers or the KW v3's as replacements. I had the most powerful S2000 there that day and I came in 11 out of 12 in my class. Humbling experience to say the least. If anyone is interested, I have a video from the instructor driving the car that I can upload so you can get an idea of how the car drove with an experienced driver. Even with him driving it still ran slower than dirt.

Don't do this.


EDIT - Here is the video:

http://www.youtube.com/watch?v=g9JfcGXaRkU

Chugs

My first thought is the alignment. With 400whp I wouldn't be the least bit surprised that the rear toe shifted. If you knew the alignment specs, that would help. I'd start there before starting to replace struts. That being said, I don't think CR struts front/AP1 rear is an ideal setup, but the difference in dampening between the two struts wouldn't be enough to make an S2000 "the worst handling car" someone has ever driven.

Did the car behave this way from the very first run(on cold tires)? Tires will heat up very quick after some powersliding around, and if you didn't check the pressures after a few runs, your pressures may have been way too high, which will cause the tires to loose their progressive feel. It would be like an on/off switch of grip vs progressive loss.

Do you have any other suspension work done? Sway bars, RCA, bump steer? How much do the springs lower the ride height, and is the ride height equal on all corners?

RedCelica

"If you let off the throttle, the front unloads and it becomes slightly unsettled."

You mean loaded...when you let off the throttle, the front loads as the weight transfers to the front of the car.

Your setup is not bad, I have a feeling this is due to alignment above all else...and/or you have a blown shock or two.

s2000Junky

Those tires exacerbated it even further with their shitty handling attributes, being a flexi, single ply sidewall constructed tire. Put a good tire on this car and that would greatly help. Don't mean to beat you up, but it makes little sense to me to over double the power output of this car, add some higher performance brake pads up front, double the spring stiffness and then put tires that handle and grip less then the ones that came on it from the factory. Poor alignment will also add to the fun.

spectacle

I'll try to answer a few questions.

I didn't check tire pressures at the track or between runs. We had a good 15-20 mins between each run and I figured that would be enough for them to cool down. The car did not behave better or worse from the first run as far as grip goes. If anything, I just became more aware of the cars handling characteristics and pussy footed my way around the course.

The Espelir springs are a moderate drop. 1.5 finger gap in the front, maybe 2 finger gap in the rear. I've had them for about 5 years and had no issues with them. I listed every suspension mod I have.

There was another AP1 at the autox with the same tires running good times. Only difference was he had OEM suspension on the car. Not sure how these tires are bad...they handle and grip great for my power on the street. As I said in the first post I don't want to argue with the "experts" here but I know they are good tires. Maybe not Star Spec good, but good in there own right.

People might think its the alignment. I can't say yea or nay there but I do know the car drives straight and has no crazy tire wear from excessive toe in or out. If one of my shocks is blown, I wouldn't know it from how calm the car drives on the street.



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GT Motoring

I would look towards the alignment first, then the added power. The alignment can do a lot - make the car handle very strangely and unpredictably. Then, Id look at the power. Too much power is a bad thing in track and autox settings. The car needs to be balanced - i.e. handling matching the power. Even at low boost, it probably still makes way, way, way more than stock.

s2000maniac

First of all those tires suck for autox. They are good for daily driving but other than they suck. I know coz I still run theses tires and on the autox, I was the slowest s2k. Gotta remember 80% of handling comes from tires and the rest from the suspension.

pastoli

You should look into a bumpsteer kit for your AP1. I have done research on this item and have heard nothing but good things. +1 on a alignment and good tires. It was night and day difference going from Sumitumo HTR ZIII's to Star Specs. It is amazing how much comes into play autocrossing. Then, when I got a solid alignment it was..... Nice!

I think that you should PM Termination. He has a decent HP car that he has set up more for autocross. He just went from All season tires to RS3's...... Night and day for him.

Carbon Blue

Regarding the rear bumpsteer kit on ap1s, they SHOULD be treated as a consumable item. There have been quite a few instances in where they snap at the joint and do some serious damage, the oem part on the other hand I have not seen any failures but again should be checked for wear and tear.

SlowTeg

As others said.

#1- Check alignment. If that's off, car could behave very unpredictably.
#2- Check suspension/shocks. You didn't say how old/how many miles are one your car/suspension. If you have a blown shock, that will also add to the fun.
#3- Look into the tires, I can't comment on those personally.
#4- Take it slow. I know this is the last thing people want to do because they want to be the fastest guy out there right from the get-go but that's just never the case. After you get everything sorted on the car.. go back and start "slow" and slowly increase your speed as you get more comfortable. I understand it can be difficult because you only have a limited # of runs, but that's the best way. With a boosted car, I imagine it being VERY easy to get the rear end to swing around if you're just barely too heavy on the gas.

I'd even recommend going to a real go karting place and take a few laps and really beat the shit out of a kart to get used to the handling characteristics of RWD. The first instinct for many people is to lift throttle completely when they feel the rear end getting light, and you have to learn not to. A few sessions out and it becomes more second nature. You need to give very light throttle to give traction to the rear when going around a turn. Having gone go karting many times, driving the s2k just felt like a big go kart. The handling characteristics are the same. Regarding the car feeling skittish when just pressing the brakes that's hard to say. Since you're unloading the rear the car will inevitably feel a little more skittish, but if it's bad then it really sounds like the alignment or possibly a blown shock.

Either way, have a good time and I think you can get a whole new appreciation for the car w/ the turns. Let your friend take it for a drive and see what he thinks, or another local s2k guy. I'm sure they can provide some input in terms of what might be wrong.