Reynard38

I have a '97 Carrera "S" with Gert's Bilsteins and H&R springs. The car sits pretty low. I had it aligned (not at the dealer) after installing the suspension about a year ago. I've got a feeling the alignment just isn't quite right. The car gets unsettled in high speed corners. I'm running Michelin PS2's at 35/39 psi. I did corner weight the car myself.
Could it be bumpsteer? Or maybe the Kinematic rear toe is out. I have heard that ONLY the dealerships can set this. True?

Edward

Hi Reynard,

Don't know specifically about your tire pressures, but they sound reasonable for 18s ...maybe drop the rears a bit for a 2psi difference, but that ain't no biggie. Bumpsteer is more pronounced the lower your car is. Mine is at about 25" to the fenderlip, and I experience no bumpsteer whatsoever, but I recall others who have posted with even lower cars that do feel it. Moreover, bumpsteer does get worse with increased speed. But it could also be incorrectly set toe. I'll leave the discussion of kinematic toe to the pros, but I also recall it said that incorrect kinematic will exhibit unsettled cornering, especially left differing from right. A good tuner may have the kinematic tool, while I've heard also of some fabricating one as well. The problem with dealers is though they may have the tool, I just don't trust them with an alignment, or my car for that matter ...but maybe that's just me
Find a good Porsche shop, perhaps a "race" or performance-oriented one to do the checking.

Edward

Sonic dB

hey guys...please define "bumpsteer" for me... I tink I know what it is...

I definitely know what a "bumsteer" is, cause Im a Detroit Lions fan.

kkim

If you have your own kinematic toe gauge you can have it set at any alignment shop willing to work with you or better yet, find an independent shop that already has one.

Have you asked the shop who did the alignment if they set the KT? If not, that could be they source of your unsettled handling.

Martin S.

Having had my car in too many hands over the years, I decided to go to ground zero and start all over. I had the rear bump steer adjusted (kinamatic toe), and then a full competition alignment and corner balance. Setting the rear bump steer is not that easy to do....and I have been told by a Porsche dealer wrench (a good one too), if the car is too low, the kinematic toe gauges cannot be used...this is hearsay...you'll have to check it out on your own.

If you want to know about bump steer, go to thisweb site and there is some good information from Longacre Racing Racer Parts Wholesale

You will note that settin up the bump steer on a car is not so simple as to use a set of gauges and wrench on an eccentric...it takes hours to get it right.

I am certain there are some 993 Racer Folks in your area that can steer (no pun intended) you to a competent shop for a bump steer adjustment and a competition alignment.

Also note, I have been told that if you want to do the front bump steer correctly, you need a pair of EVO uprights and 993 RS tie rod ends. The EVO uprights allowed for optimized steering geometry in a low car...this is what you will find on a 993RS car.

So have at it: Get Her Dun {Right the first time!}

agdamis

Reynard,

I have a similar problem with the car feeling a tad unstable when there are grooves on the highway and a sense of constant correcting of the wheel. In the European press I have read that the Carrera S is prone to this problem for a reason that was never thoroughly explained. I have not seen it discussed with the guys here. My plan is to look at the alingment settings that are posted on www.p-car.com, going to a reputable Porsche race shop (absolutely not the dealer) and starting from scratch hoping to solve it. It could be a long (and expensive) road but one that is necessary as track season will be upon us before you know it. If I find any solutions I will post them.

Bull

No problem with my lowered S with an agressive track alignment.

NoSubEDU

Bull, do you have the specs for your alignment? I need a good alignment for my C2S. I had it at VIR with a stock alignment. Car felt great, had no understeer whatsoever, but I need more camber to get more tread on the pavement. Any suggestions?

sptschoice

hi guys top of my front wheels tilt a little inward after installing shorter springs any ideas why this happen

Racer944

Hi Reynard38;

You mentioned that you corner weighted the car yourself... did you have it realigned after doing this? The alignment will be affected... and this could be part of your issue.

Cheers;
Eric

Reynard38

Corner weighted, then aligned.

Racer944

Got it... I suspected that, but just thought I would check, as I wasn't sure by reading your post the order that the work was done in.

Cheers;
Eric

Edward

Lowering a car generally results in more negative camber (where the tops of the wheels are closer together than the bottoms), which is one reason why any car needs to be realigned after ride-height changes.

Edward

sptschoice

hi edward should use camber plates to correct this problem alignment was done but problem still exist