Otto Mechanic

All -

So after 3 years, today was a good day to take my '89 S2 out for its second test drive following a fairly complete drive train and suspension refresh. The suspension wasn't really just refreshed nor was the drive train. All of it suffered from my personal opinions on performance upgrades with the intention of reproducing a Firehawk car.

My situation is that the car gets extremely tail happy exiting the apex of a turn when I apply throttle over 4000 rpm. It's possible I'm overly sensitive since I've been driving my '85 928 on this same road for over 30 years and it doesn't do this. I've had the tail break loose on me under acceleration exactly once, about 20 years ago, on a damp road in 2nd gear. It's usually very well behaved and I've learned to trust it. It was a surprise when the 944S2 broke loose; sort of an unpleasant surprise. My heart started beating a little faster as I brought it back under control. I tested my 'over 4000' theory a couple of turns later to verify, then checked under 4000 on a few turns. This one rings true.

I've put in the Lindsey adjustable rear bar, I think it's 19mm and the 30mm front bar to get as close as I can to the factory M030 package they used on the Firehawk cars (944 S2 CS I think it was).

Maybe the rear bar, which is currently neutral in the middle position of the 5 position adjustment, isn't quite right? Any other suggestions?

944crazy

If you want it to just understeer, then soften up the rear sway bar.

MAGK944

Arominus

Have you been reading ed's thread over in the autocross section?

https://rennlist.com/forums/autocros...autocross.html

V2Rocket

what springs F/R?
gas tank low? (late 944 empty vs full gas tank is over 120 lbs difference over the rear axle)
tire pressures?

4000 rpm is the torque peak for the S2 but it's so smooth its unlikely that a sudden "peak" would make the tires break loose.

my car with its lowly ~150 lbft but 200/190# springs/t-bars + 25.5/18mm sways will put the tail out, everywhere...lol

Otto Mechanic

I'd like to understeer a bit more, but not really understeer. Which direction would the rear bar go to increase understeer? Now it's set in the middle with two holes to the front and two to the rear. To increase understeer, pull the bar back to the next forward hole, or move it forward to the next rear hole?

Multiple edits to get F/R hole right. Sorry. Ask me to hold up my left hand sometime..

Otto Mechanic

No rear springs, torsion bars at factory spec. Stock front springs. 1/3 full tank. Tire pressure at 32lbs all around.

Well, it seems to do it consistently. There was a light fog, possibly some moisture on the road but it was following a heavy rain three days ago followed by dry weather.

That's more or less what I'm asking. I'm used to punching the gas exiting an apex in the 928. Not sure that's OK in an S2.

Regards,

Otto Mechanic

No but thanks, will do.

Regards,

Otto Mechanic

It's very noticeable on this car, not sure I'd still call it street though. It doesn't shake your fillings but the dashboard rattles on peddle off...

I've used the 968 parts available through Lindsey so it's clearly not an exact replica. I did the best I could

ealoken

How is the shape of your tires?

mel_t_vin

Scott, what tire/wheel combinations are you running, front and rear?

Do you have a side view of your car, as it currently sits, that you can share?

marc abrams

Scott, towards the rear. Also try increasing the rear tire pressure if you haven't done so already.

thomasmryan

T&T Racing

For oversteer, try to soft the rear sway bar by moving the drop links to the furthest hole from the sway bay mounting block, this is the longest lever arm. If still have too much oversteer, disconnect the rear sway bar drop links.

Go to www.paradigmshiftracing.com for how to correct oversteer

Otto Mechanic

OK, I'll try to answer everyone's questions in a single post, hopefully I won't leave anything out. Thanks for the pointer to Ed's thread, it was very informative and gives me a good overview and a place to start.

The tires are Cooper Zeon R53-S's front and rear. Fronts are 205x50 R17, Rear 245x45 R17. Pressure rating reads either 50 or 60lbs, I'd have to double up my glasses to be sure. They have what looks like good tread on them but I've misplaced my tread gauge. I have no idea how many miles they have on them since they were on the car when I bought it. I have them filled to 32lbs all around.

I've attached a photo from today showing the passenger side that should give some idea of the car's rake if there is any. It looks to be slightly higher in the rear.

I'll try playing with tire pressure first since it's easiest. Not sure if I should try increasing the rear pressure or decreasing front, or by how much? I'd guess maybe 2psi?

Thanks for pointing out the directionality of the rear sway adjustment. From Ed's thread, it seems I need to soften the rear bar to reduce oversteer.

All comments and suggestions appreciated,