Driving my 2001 S4 today I heard what sounded like a motorcycle
following me at a distance. The sound turned out to be from my
car. It isn't an exhaust noise because it is related to speed
rather than engine power. At 30-40 MPH it is like the rumble of
a motorcycle. At 80 it is higher pitched, a low pitched whine.
(I didn't think to check what it sounded like at 120.)
It's from behind and to the right of the driver's seat.
It sounds about the same with the sunroof open or closed.
Any idea what this might be?
The car has 66,000 miles on it. The rear differential seals
were replaced at 48,000 miles, when the dealer did a detailed
inspection for the last free service.

Signature
John Carr (jfc@mit.edu)
Tony Curran - 28 Mar 2005 03:11 GMT
Possibly a wheel bearing.
Tony
96 S6
> Driving my 2001 S4 today I heard what sounded like a motorcycle
> following me at a distance. The sound turned out to be from my
[quoted text clipped - 11 lines]
> were replaced at 48,000 miles, when the dealer did a detailed
> inspection for the last free service.
John F. Carr - 29 Mar 2005 18:57 GMT
The right, rear wheel bearing on my 2001 S4 was failing
(the quoted guess below was correct). I just had it
replaced. Is it worth preemptively replacing the other
rear bearing? I'm going to be driving a long distance
this summer and if it's going to fail I'd rather replace
it now rather than in the middle of a road trip.
The mechanic said this is a common problem on Audis.
>Possibly a wheel bearing.
>
[quoted text clipped - 16 lines]
>> were replaced at 48,000 miles, when the dealer did a detailed
>> inspection for the last free service.

Signature
John Carr (jfc@mit.edu)
KLS - 29 Mar 2005 20:16 GMT
>The right, rear wheel bearing on my 2001 S4 was failing
>(the quoted guess below was correct). I just had it
>replaced. Is it worth preemptively replacing the other
>rear bearing? I'm going to be driving a long distance
>this summer and if it's going to fail I'd rather replace
>it now rather than in the middle of a road trip.
No, don't bother. Your other bearing could go another year or more
(mine did), and any competent mechanic can replace it if you're truly
nervous about letting it go for a couple thousand miles before getting
home.
>The mechanic said this is a common problem on Audis.
>
[quoted text clipped - 18 lines]
>>> were replaced at 48,000 miles, when the dealer did a detailed
>>> inspection for the last free service.
Tony Curran - 31 Mar 2005 02:19 GMT
Wasn't really a guess. I've heard of the B series chassis having more than
its fair share of bearing failures. I have a 96 S6 with 109000kms and rear
bears are just fine - inspected 6 months ago. Had a front replaced but the
front wheel had taken a whack or big pothole.
Tony
96 S6
> The right, rear wheel bearing on my 2001 S4 was failing
> (the quoted guess below was correct). I just had it
[quoted text clipped - 25 lines]
>>> were replaced at 48,000 miles, when the dealer did a detailed
>>> inspection for the last free service.
John F. Carr - 31 Mar 2005 03:03 GMT
>Wasn't really a guess. I've heard of the B series chassis having more than
>its fair share of bearing failures. I have a 96 S6 with 109000kms and rear
>bears are just fine - inspected 6 months ago. Had a front replaced but the
>front wheel had taken a whack or big pothole.
I've lost a couple front tires to potholes but it was a rear bearing
that went. You wrote that your bearings were inspected. Is that
possible on an 01 S4? The bearings are supposed to be maintenance
free, meaning they work until they break then they have to be replaced.

Signature
John Carr (jfc@mit.edu)
Ronny - 31 Mar 2005 14:45 GMT
> >Wasn't really a guess. I've heard of the B series chassis having more than
> >its fair share of bearing failures. I have a 96 S6 with 109000kms and rear
[quoted text clipped - 5 lines]
> possible on an 01 S4? The bearings are supposed to be maintenance
> free, meaning they work until they break then they have to be replaced.
Yeah the bearings are sealed units, they basiclly go on untill you can no
longer bear the noise, there is no test to check they are gone, and my car
passed 2 MOT's with noisy bearings, there was no play or noise at low speed.
daytripper - 28 Mar 2005 04:39 GMT
>Driving my 2001 S4 today I heard what sounded like a motorcycle
>following me at a distance. The sound turned out to be from my
[quoted text clipped - 11 lines]
>were replaced at 48,000 miles, when the dealer did a detailed
>inspection for the last free service.
Is it safe to presume your S4 is left hand drive? If so, by my estimation,
"behind and to the right" would put it somewhere as near as the Torsen center
diff (tho probably not "behind" enough), the rear drive shaft and associated
u-joints, to perhaps as far as the rear diff and inboard CV joints on the half
shafts.
Otoh, wheel bearing failure can transmit some pretty harsh noise through the
drive train. Could a rear wheel bearing be within the scope of "behind and to
the right?"
Either way, if you still have a bit of warranty left, I'd scoot it into the
shop. If it's as obvious as it sounds, they ought to get it squared away...
/daytripper
'00 s4 6spd
JP Roberts - 29 Mar 2005 16:44 GMT
Rear right wheel bearing. Experienced the same last year.
JP Roberts
> Driving my 2001 S4 today I heard what sounded like a motorcycle
> following me at a distance. The sound turned out to be from my
[quoted text clipped - 11 lines]
> were replaced at 48,000 miles, when the dealer did a detailed
> inspection for the last free service.