Loose steering and vibration driving me crazy

[SpeedySpaghetti]

Hey everyone -

I'm now starting year 2 of the steering wheel shake saga... Anyway, the most recent thing I did has improve the issue significantly (maybe 75% gone now) but I still have this infuriating shake in my steering wheel at 75+ mph and a lot of bump steer / some play in my steering.

Car is 2002 S with 88k miles.

I have replaced all of the following items in search of this issue:

Tie rods (in & out)
Drop links (front)
Struts & Strut mounts (front and rear)
Control arms (front and rear)
Front tracking arms
Rear trailing arms
Wheel bearings (front)
Tires (Continental ExtremeContact DW)
Sway bar bushings (front and rear)
Multiple alignments
Multiple tire balances

All parts are OEM.

Most recently, I went to a Porsche dealer and had them align the car and balance the front wheels. The toe was set to toe out on both the front and rear which they then corrected to zero toe in on the front and slight toe in on the rear.

I'm really at my wits' end here. What else could I look at? I have thrown a ton of money at this issue and I just want to enjoy my car again.

Pretty much every shop I have taken it to has claimed it to be wheel balancing, and I have had the wheels balanced probably 5 times all on Hunter Road Force machines. Every time they balance them, they seem to be close to a 1/2 oz out of balance - is it possible that there is something inside my tie that is causing this? This issue started with my old tires and has continued with the new ones too. I've had multiple places check the rims for bends, but nothing has been noticed - only thing I can think of is that they have not checked the rims with the tires off. I have also tried different PSIs and swapping tires L/R.

Rotors have a pretty significant lip on them, but the vibration does not get any worse when braking. The vibration does seem to get a little bit better as the car warms up... any help would be awesome guys.

  

 

[JFP in PA]

I would look at two things:

 

The steering column has to u-joints in it that can come loose and/or wear:

 

 

The second thing I would look at is the amount of play or backlash in the steering rack, which should be very minimal:

 

[SpeedySpaghetti]

13 minutes ago, JFP in PA said:

I would look at two things:

 

The steering column has to u-joints in it that can come loose and/or wear:

 

 

The second thing I would look at is the amount of play or backlash in the steering rack, which should be very minimal:

 

 

Which part numbers correspond to the u-joints, and how does one check/access them? What is the best way to check the rack for play?

[JFP in PA]

I am not sure the column joints are available as a sperate part, you would need to check with a dealer on that.  There are two variant of the lower steering column where the joints are, V2 is for cars with PSM (it carries the steering angle sensor), V1 without PSM.  V2 is available as a replacement shaft with both joints, as is V1.  Replacing either requires removal of the entire steering column, which is a bear of a job.  The joints a both ends of both variants also have a locking bolt that secures the joints to splined ends of the column and steering rack, these can come loose and create the issue you are seeing.

 

You can quickly check the rack by seeing how much the steering wheel moves back and forth without the car running, there should be very little free movement.  Only check this after looking at the shaft joints above; if the shaft joints are loose or damaged, you will appear to have a bad rack when you really do not.

 

Good luck.

[JFP in PA]

Here is a photo of one of the shaft joints, you can see the bolt hole for the pinch bolt that secures it to the splined shaft ends:

 

[SpeedySpaghetti]

1 hour ago, JFP in PA said:

Here is a photo of one of the shaft joints, you can see the bolt hole for the pinch bolt that secures it to the splined shaft ends:

 

 

Is this part accessible from the interior of the car, or underneath? Is it possible to tighten them without removing the steering rack?

[JFP in PA]

6 minutes ago, SpeedySpaghetti said:

 

Is this part accessible from the interior of the car, or underneath? Is it possible to tighten them without removing the steering rack?

 

The lower one yes, the upper one is very restricted and I don't think you can get a tool on it assembled.