Vibrations on a 99 A6 Avant

I have a 99 A6 Avant that has developed a shaking in the steering wheel
and the car at high speeds. It starts around 50-60 and reaches its peak
around 70-75 (I can go faster than that and it just pretty much stays
at the same intensity level). I have taken it to my mechanic (who
frequently works on Audis and is also a family member so is
trustworthy) repeatedly and have had a regular balancing, high speed
balancing, and a four wheel alignment performed. The problem has become
slightly less intense, but not significantly. There are 4 new tires on
the car with less than 10000 miles on them.

I don't know if it's related, but the car also has a mysterious
pulsating when the wheel is turned sharply.

Any suggestions for either problem (the high speed vibrating or the
pulsating while turning) would be greatly appreciated. I read something
about a Hunter road force test in another post, but am not sure if it
applies to this situation or not. Thanks!

On 12 Mar 2006 05:44:39 -0800, "jman" > wrote:

> I have a 99 A6 Avant that has developed a shaking in the steering wheel
> and the car at high speeds. It starts around 50-60 and reaches its peak
> around 70-75 (I can go faster than that and it just pretty much stays
> at the same intensity level). I have taken it to my mechanic (who
> frequently works on Audis and is also a family member so is
> trustworthy) repeatedly and have had a regular balancing, high speed
> balancing, and a four wheel alignment performed. The problem has become
> slightly less intense, but not significantly. There are 4 new tires on
> the car with less than 10000 miles on them.
>
> I don't know if it's related, but the car also has a mysterious
> pulsating when the wheel is turned sharply.
>
> Any suggestions for either problem (the high speed vibrating or the
> pulsating while turning) would be greatly appreciated. I read something
> about a Hunter road force test in another post, but am not sure if it
> applies to this situation or not. Thanks!

Check your tires carefully for a broken belt or the beginnings of some
delamination -- you may have a bad tire. This can cause a shaking of the
steering wheel much like an unbalanced tire, but you should also notice a
slight tendency for the steering wheel to oscillate slightly at low speeds
(with your hands off the wheel). A tire with excessive radial runout will
also cause your symptoms, but they should have caught that when you had the
tires rebalanced.