Obie1

Saw an old post about this topic but there was no real conclusion. Recently the steering wheel started to wobble back and forth under normal breaking conditions usually between 30-10mph. I really don't think it is a break pad or rotar issue but I am no expert. It seems to be coming from the right rear wheel. I recently had this tire off due to a nail puncture that needed patching. I would have normally just bought a new tire/tires but I am close to upgrading to 18" twists so I decided to patch the tire. Now I have this wobble issue that I can't figure out. The tires are Pirelli P-Zeros. I am wondering if the issue could be that I just didn't tighten the lug nuts correctly since I didn't use a torque wrench when I put the repaired tire back on the car.
Any help from the experts would be greatly appreciated.

John

zoaatc11

tire may still be out of balance....

RDS928S

warped rotor is usually the cause.

Good Luck

Steve Weiner-Rennsport Systems

Hi:

"Wobbles" and such vibrations are usually caused by:

1) Tire issues; balance, out of round, or separated plies.

2) Overtorqued wheel nuts causing distorted rotor/hats and excessive axial runout.

3) Worn front A-arm bushings.

Texas993

Steve,

How can you diagnose #3? I have this issue with both of my cars. And it doesn't happen everytime. It mainly happens at speeds above 50 mph and not every time I brake.

Thanks!

1pcarnut

Need more info.
Does it start immediately when the brakes are applied and cease wobbling when the brakes are released,
or is wobbling anytime when slowing regardless of whether or not brakes are applied?

A tire balance wobble is usually speed related and not so much braking related so initial indication leans towards a rotor warped.

Texas993

In my case, it starts immediately when braking and ceased when the brake pedal is released.

On my 964, the big reds/rotors are pretty new - just a few thousand miles old.

Steve Weiner-Rennsport Systems

The way I do it is to insert a big prybar into the space where the front bushing fits the control arm and see how much deflection you get. Its a judgement call but it should not move easily or very much.

chris walrod

Here is what you'll see in a cracked or failed control arm bushing when deflected.

niche

I have a similar problem. I can specify though it usually happens when I'm on highway and I'm slowing down. To be specific at about 4th gear and 3k rpm. Could this be the same bushing issue. Brakes are brand new, so that can't be.

Steve Weiner-Rennsport Systems

Might be,..the only way you will know is to put the car on a lift and do the prybar test.

IMHO, as the whole fleet of 993's gets older and accumulates more mileage, you'll see more and more of this. Rubber deterioration is due to mileage as well as environmental factors (UV and ozone) so its difficult to predict how long they last on each car.

Texas993

Thanks Steve and Chris. I am afraid that this is the issue with my cars. I will have RUF take a look the next time the cars are there.

RallyJon

Here's the pic from the magazine article:

aperalta

The bad news...you cannot just replace the bushings. Porsche requires you replace the whole control arm ,unless you go with aftermarket polyurythane bushings which people have said are squicky/noisy.

cgfen

hmmmmmmmmmmm it's a crying shame that no one has adequate replacement bushings available to press into the existing A arm.

I'll bet that if someone did have replacement bushings available, particularly if they were designed for just this application, that there would be a market for them.

Hi Chris, Happy New Year.

Cheers

Craig