ALMOST have solved my vibration issue - need a bit more help
 

Hey everyone,

So I'm still on my journey to track down an annoying steering shake and kinda loose feeling in my steering/car. Nothing big happened to bring the issue on - no accidents or potholes, I just drove the car one day and it started and has not gone away since.

The vibration is most noticeable after 80 mph and the car does not feel stable as it should. Also, when taking higher speed corners (anything over 40) the car does not feel as "on rails" as it used to. It feels like it wants to oversteer / the steering does not feel as stiff as it should. I have noticed that my driver side mirror vibrates a lot - which would lead me to think that the issue is on that side. This mirror vibration got a lot better once I changed the rotors but it is still there. The car is 2002 S with 88k miles in 6 speed.

Here is what I have done so far:

Tie rods (in & out)
Drop links (front)
Struts & Strut mounts (front and rear)
Control arms (front and rear)
Front tracking arms
Rear trailing arms (or tracking arms? they are the ones that go diagonally from the front of the car to the control arm. I have not done the ones that go straight from the chassis near the strut to the control arm - could these be the culprit?)
Wheel bearings (front)
Tires (Continental ExtremeContact DW)
Sway bar bushings (front and rear)
New rotors (front and rear)
New pads (front and rear)
Multiple alignments
Multiple tire balances

All parts are OEM.

The most recent things I changed were the rotors and those actually really helped. Both had very significant lips on them, so I image there must have been some out of true-ness/round on them as well. These got the problem to about 90% resolved but I want to get it to 100% before I give up and sell the car. I've been sooo many shops and no one really seems to be able to pinpoint it. A lot have said wheel balancing, but I've had the wheels balanced many times on Hunter Road Force machines and every time they come out about 1/2 oz out of balance but it does not resolve the issue.

What else can it be? I've tried swapping rims with another member, but that did not change the issue. Could axles/CV joints be the culprit? I know the PO put aftermarket boots on the CV joints so I imagine something was done there but I have no documentation. The car felt incredible for about 9 months from when I bought it, but since then it has been a nightmare due to this issue.

Thanks for any help!

Sounds like you have toe-out. Get the front toe-in checked.

I've had the alignment done by three different shops but that has not improved the problem. Would rear wheel bearings potentially cause this? I did not notice any shake at 9 and 3 or 6 and 12 with the wheels on nor is it making any bearing type noise, but I'm running out of components to check / replace.

Wheel bearings usually change the noise as you make left and right turns. If this doesn't happen to you I doubt its a wheel bearing.

Do you have spacers?

If so, hub-centric rings would be better...spacers can cause vibrations as they may not seat correctly on the hubs.

it's not rear wheel bearings or toe out. non-hubcentric spacers is a good thought.
sounds like a tough one. What about the rims themselves being out of balance?

is it RPM dependent or strictly speed dependent? Front or rear of the car?

EDIT - just read the symptoms in the steering. Maybe it's a bad steering rack or steering linkage?

these may be long shots but my only other thoughts are a bent spindle on the front wheel carrier, possibly bent axles? or possibly bad motor/gearbox mounts. On my BMW M3 I had a really bad driveline vibration that finally turned out to be a shot differential mount

Yup...spacers have some wiggle room, thus a hub-centric ring would ensure all is properly centred. You can get crap behind the spacer too that will not allow it to seat flush on the hub. A steel hub vs. aluminum spacer = corrosion...the two metals don't get along well.

I was also thinking some sort of steering box/rack/bearing issue too...he said it was in the steering wheel...can't be the tire if he swapped someone's rim and it still does it.

Go over all bolts and re-tighten to spec?

Frustrating I'm sure.

:cheers:

No, no spacers on the car.

Hey thanks for the taking the time to respond.

I've had the rims inspected and I've tried different rims but that did not solve it. I've replaced basically everything in the steering system besides the rack but it has not really changed anything. How would I inspect the rack? There is not leakage or anything through the boots.

I had someone check the motor mount an they said it looked fine, but I don't know if they actually took it out of the car or just wiggled it. I have a new mount sitting in my garage, I just need to get around to swapping it in.

How would I go about diagnosing the axles? Wouldn't an axle issue be more present during acceleration?

Thanks again!

Very frustrating... I'm pretty sure I've removed and re-torqued every bolt on this G-D car... I just want to enjoy my car again!

vibration
 

This may be a stupid reply but I needed to buy a new left front cooling fan for my 99 box. Reading reviews the cheaper ones had complaints of vibration strong enough to feel it through the steering wheel. I went with the OEM which was $100 more to make sure I didn't cause an issue.
Maybe you have a piece missing off a fan blade? Just a thought.

Interesting idea - I haven't cleaned my radiators in a while so I might as well check this. Thanks!

any luck with the fans??

Hi! Did you arrive at some sort of conclusion?

I have the exact same problem and like you I've changed every suspension component on the car. Plus, I've changed gearbox and motor mounts also. Every new part seems to do some little benefit but nothing major. Previously the car was very precise and enjoyable.

The only slight different symptom mine does is that the shaking on some days is more severe than others. But even this is totally random.

I have also taken the car to a Porsche dealer. They say it's a wheel/tire balance problem. Can't be as I've used 3 sets of tires on it since and tried different wheels along the way. Also different tire shops didn't find any unbalance problem and always end up saying must be something mechanical. Very frustrating.