Techno Duck

Still getting used to this car, have about 200 miles on it so far. 57k miles (no track), brand new PS2's in stock sizes and fresh off the scales from a corner balance / alignment / bump steer. The front and rear toe links were replaced with spherical. Transmission mount is the updated 997 part, has 15k miles on it.

Ive noticed a bit of a unsettling characteristic from the rear. If you lift while turning, i can feel the car yaw / or pull slightly in the direction i am turning. I know... 'no lift'. But you can feel it even on long sweeping turns on the highway, not just driving it through the canyons. Once it 'settles'. it feels nice and planted.

Ive had cars with both worn and good LSD's and don't recall ever feeling this behavior. Is this what a worn out diff on a GT3 feels like? I am thinking of going Guards rebuilt sooner rather than later now.

Any other ideas? Engine mounts? Rubber elsewhere in the suspension? Tire squirming? I think realistically this will stay a street car for me, so i don't really want to go spherical everything.

Its one hell of a car though!

Matt Lane

Hmmm, I am sure someone more knowledgeable can chime in - but what you are describing is very pronounced if you're noticing it just lifting throttle on the highway... something is not right. Do you have locking plates on your rear toe links? I know those will otherwise come loose, but not in 200 miles of street use (?)

I am sure you can sort it out with help form folks here but ultimately with a setup/alignment shop you trust.

I have 3 years on mine, and I purposely did not change anything in the suspension other than what was required for safety and alignment (adjustable toe links w/ locking plates, and caster pucks to clear the front wheel liners when lowered and aligned). Did about 50 track days, and it handles great. I don't think you need or want to replace the rubber on a street car - at least, IMO, that's not the source of your symptoms described above.

Set up right, these are GREAT drivers cars!

Cheers

Matt

cs81

+1

I noticed this as well the first time I drove mine home (4 hour drive on highway). Put 2k mi on mine so far.

I've always driven AWD cars so assumed had something to do with RWD and/or LSD.

Curious to see what others have to say.

Welty

My experiences a tad different. On our local track (Thunderhill-Willows, CA) at the end of the longest straight. When I would lift and brake hard. The rear end became very loose (left/right-up/down) to the point I would hang on and hope the track gods were going to be good to me entering T1. Exciting enough, I wanted to go back to my past M3s. It seemed upon review/replacement that the 996 GT3 OEM LSD was tired. Upon replacing the OEM LSD with a Guards LSD, no future loose rear end issues to report.

Stephen Tinker

You would think that with 57,000 miles on the car, the LSD would be next to useless.... Also uneven tyre pressures can cause "pulling" to one side under acceleration / deceleration too.
Whether this has any bearing on the problem is a moot point, but viewing the alignment specs that has just been performed may also give an indication of the problem.

AudiOn19s

Mike Murphy

I agree, please post your alignment settings. Also, new tires could be a little greasy.

Gadsby

Techno Duck

I am confident in the shop that did the setup. Will post the alignment numbers when i get them.. it was done via string, so no print out. I also did check tire pressure yesterday morning... 32/39.

I should also mention that i felt this same condition right after buying the car; this was with corded PS2's and questionable alignment. It did feel more pronounced, but i only drove the car maybe 50 miles gently. Was hoping the alignment and new PS2's would have addressed it.

I know at this mileage the LSD probably isn't doing anything and other suspension links are questionable. Just wondering if one or the other was more likely the cause.

Gadsby

Check the thrust arm bushings, one in the arm the other in the control arm. If rubber is perished it will allow the wheel to toe in, if severely perished it can allow the wheel rotate to the point it can hit the thrust arm under hi load. Good luck Im sure you'll find it.

mistermct

In addition to all the comments above, I notice you're running OEM pressures. I did not like the feel of OEM pressure at all.. the rears were way too unstable, very much as you described. Going to powdrhound's recommendation of 32/33, transformed the handling. Amazing.. never looked back.

FYI I replaced old rubber immediately with AD08R so not a direct comparison tirewise to your PS2. In case you're interested in wear... I put 15k kms and 4 track days on the tires and I'm just past the 2/32nds wear bars on the inner of the rear tire. Wear is linear across the tire with about 3/32nds on outside.

Techno Duck

Will pull the wheels off and take a closer look at the bushings tomorrow.

Ill play around with the tire pressures also. Still very new to this car, so wanted to try it as Porsche intended it... .

Any thoughts on worn engine mounts?

Thankfully Black Friday sales are coming soon...

Marv

Can you provide a picture of the tail of the car. Worn mounts have the tail pipes sitting a little low and the gap between bumper and pipes is a clue.

I put RSS mounts on mine and it made a huge difference in tightening up the tail, but you get a lot more ride harshness and noise for your efforts.

Mike Murphy

AudiOn19s

worn LSD isn't going to cause the condition you're describing mid turn, I'd be really surprised if worn motor mounts did either.

If the toe was set where it's supposed to be then Gadsby is on the right track. He has an old post around here somewhere showing that his rubber bushings were soo worn causing enough deflection to cause tire rub under load.

I'm not bashing anyone who does alignments with strings, i used to string align my M3 all the time, but the rear of these cars is so finiky when it comes to everything being precise that I'm not sure I'd trust strings. Our 997 turbo was lowered by the previous owner and the rear toe was off just enough that the rear of the car felt horrible mid corner like it was moving all over the place (it was the definition of bump steer). A toe adjustment of .08 degrees per side made all of the difference between unstable and completely confidence inspiring.