I just picked up an S2000, and the dealer put some brand new terrible tires on the rears. I don't know if that has anything to do with this, but I noticed on the way driving the car home that if I accelerate through a corner, the car wants to go straight, then as soon as I let off the gas, the car pulls back inline. I'm not putting down a lot of power or even cornering hard, just typical getting on an on-ramp and accelerating up to the speed of traffic. There's definitely nowhere near enough power to be causing the wheels to slip. I don't remember my last S2000 acting like this.

I'm hesitant to take the car in for an alignment, because I plan on putting some kw's on the car soon, and it seems like a waste to get the car aligned right before that. If that could be the issue, then I'll definitely get it checked out. What I'm worried about, is that it could be an issue with the LSD.

 

I had the same exact issue! Most noticeable on curved highway on and off ramps, but was also present in low speed (20-30 mph) situations.

Check your tire pressures!!! This is most likely the culprit. S2Ks are very sensitive to tire pressure. Another theory could be that the front tires are worn and have less grip than the new rear tires and the car is pushing through corners.

I had the problem and took the car in to get the alignment checked. My front tire pressure was down by 4 lbs in each tire. If you buy one of the 1 yr alignment packages from NTB then just take the car back in with the KW's on and they will align for free. Make sure if you're lowering the car to go to a shop that can accomodate your car on the rack after it has been lowered. I've had issues with this as I'm lowered 1.5".

Good luck!

 

Soft sidewall tires allow more weight to shift and don't work well with the s2000 suspension imo

 

Acceleration => unloads the fronts => more understeer
Deceleration => loads the fronts => more oversteer

Understeer on acceleration is the perfectly natural/normal response of a responsive, balanced car. Up to the point that you begin to break the rear tires loose.

Likewise, getting off the gas naturally gives more oversteer/reduced understeer, pointing the car into a turn.

This is driving 101, folks...

 

I have noticed the same thing with mine. Like you, I assumed it was something to do with LSD, so I changed the oil and it's a lot better.

 

ZDan, that would be an excellent response if I was driving anywhere near the limits of grip for either the front or rear tires. I'm not sure if you read my original post all the way through, but the issue occurs at very low cornering loads, with very little torque being generated by the engine. (What does a stock s2k make at 3,000 rpms, like 10 lb/ft? ) Thanks for the response though?

It feels like when my Evo had the tires rotated and the wear must have been uneven. The car would pull to the left when you accelerated, and to the right when you decelerated. Only with the S, it doesn't pull in a particular direction.

I'll definitely check out the tire pressures, and not knowing the previous maintenance, I'm sure it wouldn't be a bad idea to replace some of the fluids, including the rear diff fluid. The terrible tires will have to stay on the car for now however, since I plan to pick up some wheels very soon. Thanks for the responses everyone.

 

What tires and how do you know you're not near the limits of the tires?

 

I don't know how to answer this without sounding rude. I know I'm not near the limits of the tires because I'm not a total dunce. Like I said, this is at very low cornering loads with very little torque. Having said that, I'm obviously half of a dunce because I didn't think to check tire pressures first. Fronts were in the mid-40's, so I got them back down to 32psi (cold.) Rears were only a few psi over-inflated. I fixed those as well, but this didn't help.

I'm pretty sure it's the squishy sidewalls on the tires (which are Doral tires btw. Never heard of them? Me neither.)

I have a hypothesis as to what's happening. Once the car has entered a steady state in a corner (low g-forces, nowhere near the limits of adhesion) there is a little more weight on the outside tire. Because the sidewall is so squishy, it makes the effective diameter of the outside tire less than the inside tire. If you've ever put a brand new tire on an axle with a worn tire on it, you know that differences in tire diameter will make your LSD act funky and put power down in weird ways. I think that's what's happening. I get the feeling there won't be a lot of people who can confirm this because none of us would put such terrible tires on such a great handling car.

So unfortunately this issue will linger until I get new wheels/tires in the next month or so.

 

Worth pointing out that you can feel small differences in slip angle WAY below the limits of adhesion. Particularly with crap tires. Are the fronts still OEM? For sure crap rears with good fronts shouldn't cause a ton of understeer on acceleration around a corner, but they of course would give more oversteer when you got off the gas. Maybe the increased relative difference made it seem more understeery on accel.

Anyway, if the behavior is symmetrical (does the same on left-handers as right-handers), I agree with your approach to wait and see how it does with proper tires all around. And of course any alignment issues will presumably be addressed when you get the coil-overs.

 

It does occur on both right and left hand corners, but does not pull in either direction when I am accelerating in a straight line, so I'm hoping it's just the crap tires. I can't wait to get these things off the car.

Thanks for the input everyone.