Author Topic: Wheel bearing? CV Joint?  (Read 1422 times)

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jfrahm

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Wheel bearing? CV Joint?
« on: January 12, 2006, 04:58:37 PM »
On my way back from Vail I started to notice some noise and vibration from the front of my A8 Quattro.  It is a quiet hum that only the driver can really feel and hear, and it is only noticeable above 45 MPH.  It starts out pretty low and slow (about every 2 seconds) and get s a little louder and faster as speed increases, but never very loud or fast.  It is a lot slower than the tire RPM, would be about 10 revs per second or so.  So this noise is coming up every 20 revolutions of the wheel and axle.

Something like this:
.................mmmmMMMMMMMmmmm...................mmmmMMMMMMMMmmmm.......

It is still there if I shift to neutral and coast.  The tires are new Michelin X-ice with 250 miles on them, they were quiet until Sunday.  I think the noise is from the left front but I am not 100% sure.  I can feel the vibration in the pedals more than the steering wheel though.  The sound might be there below 45mph but too quiet to hear/feel.

Any guesses what it might be?

Thanks,
-Joel.

P.S. the A8 really storms up those mountains.
2001 Audi A8 Quattro 4.2l

Eric18T

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Re: Wheel bearing? CV Joint?
« Reply #1 on: January 12, 2006, 06:11:49 PM »
so if it is alot slower than than the tire rpm that it has to be something that is geared down and thus making less rpm. What is in the front end that would be geared down that could make that sound?

Is it doing it still today? or was it just on sunday?

Rocky Mountain Club B5

Re: Wheel bearing? CV Joint?
« Reply #1 on: January 12, 2006, 06:11:49 PM »

jfrahm

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Re: Wheel bearing? CV Joint?
« Reply #2 on: January 12, 2006, 06:35:58 PM »
It was doing it when I drove home on Wed.  I have not driven the car yet today.

The frequency makes me think about a bearing or something where several things have to line up  rather than an issue with a tire that comes around 10x a second.  It could be a bearing in the front differential, I will try to listen as I go around corners and change the realtive speeds of the front wheels (thus spinning the spider gears at different rates.)

-Joel.
2001 Audi A8 Quattro 4.2l