Loose steering and vibration driving me crazy

[SpeedySpaghetti]

Hey everyone -

 

2002 Boxster S, 87k miles, 18 inch turbo twists.

 

I've been trying to track down an issue that makes my steering feel loose and sloppier along with a slight vibration I can feel in the steering wheel. I also get a lot of steering kickback when I drive over bumpy roads - the steering wheel violently shakes from side to side on road full of ruts/imperfections.

The vibration and sloppy steering is noticeably worse on rough roads, and seems to improve a bit on smoother pavement. The steering wheel shake gets worse on the freeway around 75 mph. I have also noticed that my driver-side side view mirror seems to vibrate while my passenger side one stays perfectly still. So far I have done the following:

So far I have done the following:
New tie rods (inner + outer)
New front drop links
New sway bar bushings (front + rear)
New control arms (front + rear)
New track arms
New trailing arms
New struts (Bilstein B4)
New strut mounts (front)
New tires (Conti ExtremeContact DW)
New front wheel bearings
4 Wheel Alignment
Wheel balancing @ a reputable shop

I've had all four wheels checked for bends/defects and they are all arrow straight

I have done all of the work myself (except for the alignment, balancing, and tire mounting), but I've been to a few different specialist shops and no one has been able to fully solve the issue. The parts I replaced have improved on the issue, but the car still does not feel like it did before this issue arose. I can't really find any play when pulling on the wheels nor is there a noticeable drone at highway speeds. Does the actual steering rack play a role in this? Could it be the motor mount that causes this?

[wizard]

I once had a similar sort of issue. It turned out to be two lug nuts working themselves loose on a front wheel.

 

Whilst I'm not suggesting this in your case, it may be an idea to double check that everything is torqued to spec ... and thread-locked, as necessary.

 

 

 

[DBJoe996]

Seems you have replaced just about every part that would play a role in this, and had things checked and an alignment done.  Not that it is common, but I wonder if the steering shaft has some play in it, i.e., the spline shaft and the universal joints.  Might be worth it to check the bolts that hold the steering shaft #10 and #35 here - http://www.autoatlanta.com/porsche-parts/hardparts.php?dir=996-99-05&section=403-05

[SpeedySpaghetti]

2 hours ago, DBJoe996 said:

Seems you have replaced just about every part that would play a role in this, and had things checked and an alignment done.  Not that it is common, but I wonder if the steering shaft has some play in it, i.e., the spline shaft and the universal joints.  Might be worth it to check the bolts that hold the steering shaft #10 and #35 here - http://www.autoatlanta.com/porsche-parts/hardparts.php?dir=996-99-05&section=403-05

 

How would I access #35 - under the steering wheel?

[SpeedySpaghetti]

7 hours ago, wizard said:

I once had a similar sort of issue. It turned out to be two lug nuts working themselves loose on a front wheel.

 

Whilst I'm not suggesting this in your case, it may be an idea to double check that everything is torqued to spec ... and thread-locked, as necessary.

 

 

 

 

Yeah it feels like both of my front wheels are square or something, but I've undone and re-done the lug nuts multiple times and everything up there is torqued to spec.

 

[wizard]

Sorry. Not specific enough, perhaps. The lug nuts reference was just an example.

 

When you turn the steering wheel just a fraction, is there a corresponding turning of the wheels?

 

When you slowly apply full lock in each direction at standstill with the engine running, is there any noise other than the tires against the road surface?

[DBJoe996]

Actually I don't know where #35 can be seen or reached.  Sorry not much help there.  May have to trace the steering shaft up under the dash and go from there.  Someone else was having some problems with new Conti tires.  Seems molding lubricant in tire manufacturing was making the tires feel slippery.  Have you considered a Hunter Road Force balance?  Could be something going on with the tires and wheel combinations.  Are you running wheel spacers?

Edited September 27, 2018 by DBJoe996

[SpeedySpaghetti]

2 hours ago, wizard said:

Sorry. Not specific enough, perhaps. The lug nuts reference was just an example.

 

When you turn the steering wheel just a fraction, is there a corresponding turning of the wheels?

 

When you slowly apply full lock in each direction at standstill with the engine running, is there any noise other than the tires against the road surface?

 

Yeah, the steering wheel seems to be pretty responsive to the steering inputs.

 

I'll run the second test today when I get off work - from what I remember, there is no clunking besides the wheel turning.

[SpeedySpaghetti]

2 hours ago, DBJoe996 said:

Actually I don't know where #35 can be seen or reached.  Sorry not much help there.  May have to trace the steering shaft up under the dash and go from there.  Someone else was having some problems with new Conti tires.  Seems molding lubricant in tire manufacturing was making the tires feel slippery.  Have you considered a Hunter Road Force balance?  Could be something going on with the tires and wheel combinations.  Are you running wheel spacers?

 

I thought my tire was slipping on the rim earlier this week when I referenced them off the center caps, but the center caps might also just be loose. I'm going to index the tire off of the valve stem tonight and see if it is slipping. I've had the tires road force balanced twice, but no improvement. No wheel spacers - stock 18" rims and the problem started before I put on the Conti tires. The previous owner had these horrible Nankangs on there, but they worked just fine for about 8 months before the problem started. The car felt great on my way to work that day, and then when I got back into it to drive home, it just felt off. This was about a year ago and I've been trying to track down this issue since then.

[wizard]

Bizarre.

 

The only other explanation that I could have given is that while you were parked up on that particular day, somebody hit your driver side front wheel and bent it out of shape ... but obviously not!

 

It may be an idea to check if both front tyres have identical wear patterns.

Edited September 27, 2018 by wizard