My 98 z28 a4 is making a soft rumbling/thumping noise when turning right, even ever so slightly. When I'm on the freeway going straight the noise goes away, but right when a right curve comes about and when I slightly turn the steering wheel, I hear the thumping noise. It sounds almost like a bubble on a tire or even a wheel with loose lug nuts, but it's not. It happens most often when I am above 40 miles and beyond. I feel the slight rumbling on my steering wheel too. When I am on a left curve, there is no noise.

I already rotated the wheels with the same result.

I jacked up all four wheels and they don't move around when I pull on it and rock them sideways. So I don't think its the wheel bearings.

I read some threads and some people say it's normal on a Torsen, but I think I have an Auburn.

What can it be?

 

Sounds precisely like my problem on the passenger side in my RS -- new wheel bearing needed. My sound was more of a horn-like slight grinding/whirring noise. All your description was the same for me, except mine was left curves -- longer gradual ones made the sound evident.

 

try taking the calipers off and then test the bearings. should get a rumble from the bad one when spinning. i changed both on mine when one went. figured the other would be failing soon too.

 

What exactly do you mean ? With the caliper off the brake rotors will move around and make noise if I spin it.

 

I think he means take the rotor off too, then spin it.

 

Any more possibilities?

 

^ Have you ensured your wheels are balanced recently?

 

If you wanted to keep the rotor on, you could run a couple lug nuts back on the studs to clamp it back down to the hub.

 

I spun both wheels and they do not have weird noises or movement. Sigh

 

Sorry, I meant both hubs with wheel off. On phone can't edit.