Rear toe is minimal.. I'll look up my exact settings when I get home. Yup.. car has LSD. Judging by the comments so far.. it seems like the best plan of attack is to drop the rear bar to the soft setting and give it a try.

 

Yeah, definitely do that. More rear toe in would make rear end more stable, and more rear negative camber would increase the rear end grip.

 

So you were off the pedals and the back end stepped out? I'd agree with the others, lower the rear and if that doesn't do it change the sway bar to the soft setting...

You did the right thing in getting on the gas when the backend stepped out IMO.

 

I was about 1/4 throttle maintaining speed.

Here are my alignment specs:

LF RF
Caster 2.1 2.2
Camber 0.0 0.0
Toe .08 .08
Total Toe .17

LR RR
Camber -.5 -.5
Toe .14 .11
Total Toe .23

Whatcha' think?

 

You have 0 camber in the front?? That really stands out. Basically this means that whenever you go into a turn, you will be seeing positive camber...not good from a handling or tire wear perspective.


Toe looks good, but I think most will recommend more caster.

 

Adrial - he is trying to decrease oversteer. You have suggested 2 things which will worsen the problem. Lowering rear ride height shifts weight bias rearward = oversteer. Adding negative front camber = oversteer.

 

I understand adding negative front camber will add oversteer, but once he gets the car straightened out otherwise...I think he should add some negative camber. I dont think his alignment is the cause of the handling condition he has.

As for lowering the rear... https://rennlist.com/forums/showthre...threadid=79154 . So...Who's right? (serious question). I would think that shifting the weight bias to the rear would give the rear more grip and hence less oversteer/more understeer. Frictional force = Mu * Normal Force .

EDIT:
Maybe this list will help ya Perry...taken from CJV on the 996TT forum (https://rennlist.com/forums/showthre...threadid=80080):

"Suggestions to correct (follow @ own risk)

Oversteer: loose or rear tires slide out

Possible Corrections:

01) Lower front tire pressure
02) Raise rear tire pressure
03) Stiffen front shocks
04) Soften rear shocks
05) Raise front end
06) Lower rear end
07) Reduce rear track
08) Install narrow front tires
09) Install wider rear tires
10) Stiffen front sway bar
11) Soften rear sway bar
12) More front toe in
13) Reduce positive caster
14) Reduce front negative camber
15) Stiffen front springs
16) Soften rear springs
17) Use harder front tire compound
18) use softer rear tire compound
19) Add weight to front of vehicle
20) Remove weight from rear of vehicle
21) You may be going too deep into your turns
22) You may be getting on throttle too early
23) At high speed.... increase rear wing downforce
24) You may have too much rear brake

A good suggestion is too change one thing at a time and take notes.

Tight courses require more over steer, fast courses more understeer.

* Information was obtained from Kraus Racing "

 

I'm interested to hear how your tuning efforts work Brian.

I think I'd tackle this starting with the easiest items first, one at a time, until you get where you want to be. I.e., try different air pressure combinations first, then adjust the rear sway bar, etc.

I installed the M030 968 bars on my car this spring but I haven't had a chance to do any serious driving and tuning. I do know the couple times I tried mashing the throttle while starting off into a turn swung the rear end around very quickly and violently. I'm currently at the middle setting on the rear bar, but think I'll go softer before my first DE.

Good luck.
Ron

 

I hope you get it straightened out Perry. Let us know how things work out.
I have a stock suspension setup on my S and It seems very predictable.
A little understeer off throttle and a little oversteer on the gas.

 

Oh, and may I add that I suggest autocross before DE/track to get a feel for how the car handles...

 

I'm thinking too high of air presure in the rear, what is it at? Alsso figure on a hot day like we've been having and up to temp as far a tires go, you could add 4-7psi to what they are at, maybe more. You sure there wans't a little bump or expansion joint in the corner that made it skip out from under you? I found the expansion joint on Reagan east to 75S at 80, it wasn't fun, but I kept her, I just had to drift her out to get some traction back. I agree with adding some camber in the front too, less pushy once you get the rear taken care of and sticking, the front will tend to push with 0.0 camber.

 

Perry,
It is VERY hard to understand the handling balance on the street. Conditions change all the time. There have been many times on the track when the car changes from oversteer to understeer or the other direction.

This weekend I went to Willow Springs. First session I have lots of oversteer and in general very low grip. I went off track twice in turn 9. One spin just dusted the car and the next sent me off into the dirt berm about 150 feet off track. I tore up the front spoiler and bent a control arm.

Last time out my car was PERFECT. I made no changes to tire pressures, sway bars, or shocks. Track conditions changed.

Road conditons can change even more. Best thing to do is do Autocross. Feel what the car is doing at the autocross and make some changes. Use this to dail in the car.

 

I plan to take it out to an AX and a DE to sort it out as much as possible. That has been my plan for many years.... kinda got side tracked.

Rear pressure is 33psi cold, about 37psi hot off the highway. I have been trying to keep everything as close to the way I ran it before.

The front is wonderful.. takes some extra steering effort, but it won't budge.. no push what-so-ever. It's solid.

I dropped the rear bar to full soft last night, but did not have a chance to take it out for a test run. Rain today.. so it's at home in the garage.

If that does not work, I'll add some stiffness to the Fron't Konis. If I still have issues... I start dropping tire pressures.

 

Take a look at this site, it might help you balance your shocks/struts:

944 Suspension

Here is his recomendation: 70% stiff in front, 50% stiff rear.

 

I bet you have been lucky in previously catching a slide by getting on the throttle - best thing is to feather it at most. I find in the 944s I've owned over the years I always catch a slide by keeping roughly the same throttle input (at most) and steering through it, or simply getting off the gas...YMMV Al