996 Understeer

[Long Islander]

Last weekend, I participated in a PCA autocross, and once again experienced significant understeer in my 2001 C2. One of the instructors who had a 996 race car told me to have the front wheels aligned by a Porsche dealer to GT3 specifications, which should make them tilt inward more at the top and lessen, if not eliminate the under steer.

Has anyone had this done? If so, what does it cost, and was the difference noticeable?

On a related note, I left the PSM engaged the whole time, but this didn't do anything to elimiinate the understeer. Is it supposed to kick in only to prevent oversteer?

One last thing. Just after the finish line, hard braking was called for, which resulted in plenty of front wheel lock up in my case. Isn't the ABS supposed to prevent lock up? How can I test if my ABS is working at all?

[nick49]

I was told a larger diameter rear sway bar will help, also wider front wheels and tires, play around with tire pressures and try more agressive negative camber on front.

[bnewport]

An alignment at a dealer is usually about 150 bucks. They can put about 0.5 degrees of camber on a stock 996 as far as I know which helps a little. More camber would require GT3 lower control arms or camber plates or a suspension with built in plates like JIC Cross.

Next time it understeers try lifting briefly on the throttle which should move weight to the front and make it hook up, don't do this if you have been putting more and more lock on in a vain attempt to get rid of the understeer as once the weight shifts to the front, you'll spin in no time.

Edited October 26, 2006 by bnewport

[BjornH]

They can put about 0.5 degrees of camber on a stock 996 as far as I know which helps a little. More camber would require GT3 lower control arms or camber plates or a suspension with built in plates like JIC Cross.

I run 1,30 deg negative camber in the front on my C4 -99. (I wanted more, but that´s the most we could achieve). The car has ROW030 suspension but no camber plates or GT3 parts.

My car is very well balanced and can be made to under- or oversteer at will. Responsive at the track wihout being twichy on the street.

The specs are:

Front:

Caster: +8,2 deg

Camber: - 1,3 deg

Toe: + 0,5 deg (toe in)

Rear

Camber: - 1,25 deg

Toe: + 0,12 deg (toe in)

[Hroussard]

Oggie... you left you PSM on??? Why . The fun is in turning all that stuff off. The car will just ""fight" you and feel unnatural because you are exceeding the "safe driving limits" and that's what all these systems try to make you adhere to.

Just turn all the crap off and do some more crossing. You will not believe what a difference that makes and how suddenly all of the built-in driving caracteristics come back and help you. You will see how the tail hanging out for instance is easy to control , how you can move the weight from back to front and how LATE you can brake provided you are prepared to stump on the brake pedal. My instructor once told me that he did not believe that a 996 could stop that good ( I have just standard brakes, rotors, pads and 18 inch wheels) ohh. and a heavy foot!!

Enjoy!

[Izzy]

I agree with Harry. I was tracking my '03 coupe and it was feeling sluggish out of corners. My '99 cabrio (doesnt' have PSM) felt a lot better on the same track, and I was beginning to think "should have driven the old one". Then I remembered to turn off the PSM on the coupe. Man! What a world of difference, you can take the corners screaming fast and the exit speeds are awesome. That is all it took. I always keep the PSM for daily driving, though.