It seems my GTU has developed a bad vibration in the front end. I think it may be the tires at this point, but want to see if I'm overlooking something.

So far, I've replaced: ball joints, struts, springs, resurfaced brake rotors (new pads, just a brake job) and had the tires re-balanced and a 4-wheel alignment.

The steering wheel vibrates beginning around 55 - 60 mph. It does seem to be consistent up to around 80. I cannot detect anything at or below 40 mph.

The tie rod ends and wheel bearings all check out OK, but they are original and the car has approximately 140k on it. When I replaced the struts and springs, I did not replace the strut tower seats; they seemed fine and within spec.

The tires were new around 4 years ago. They sat on a car in a garage and it did not move; I pulled them off this other car and put them (wheels too, off of an S4 TII) on the GTU. I have put a few hundred miles on them and expect that any flat spots should be gone now. The left front ball joint did fail and I had to drive about 120 miles on it (it didn't let go, just developed an extreme amount of play).

Should I consider the tires suspect? Would it be advisable to look elsewhere, and if so, where?

 

Sitting without moving for years is a clue. I have a old MG Midget which sat unmoved for 3 years, and the front end shook really badly when I finally got it on the road. Balanced the tires. No change. Checked all the usual suspects, and they checked out good. Then one day I had the front end jacked up, with the tires about an inch off the ground, and for no real reason, I spun the driver's side tire. It spun around a 1/2 turn, and then stopped as part of the tire hit the ground. Turned out that they had become flat-spotted from sitting so long. New tires cured it.

 

I can replace the tires and probably should do that. If that fails to correct the vibration, what would be the next step?

 

I'd start with the new tires, properly balanced, before jumping ahead. But if all of the suspension/steering components are in proper condition, there's a possibility the steering rack could play a part in vibration, but I would check out EVERYTHING else very carefully before changing the rack. A good alignment shop will find if there is anything not up to spec in the steering/suspension before they do the alignment, so that's an option, too.