[Biturbos4] A whine from the rear

Wilson Northrup northrup at crazybug.com
Thu Jul 13 17:35:15 EDT 2006

Ring and pinion, good suggestion.

Along those same lines,  you might simply check the oil level first... or 
replace the oil to see if the sound will lessen or go away.

I'd probably go with one of the synthetic oil products.  I'm use a Redline 
Oil product (the weight escapes my memory, GL4 75/90?)  at the moment in 
my diff, but other vendors make good products as well.

i believe the biturbo s4 is also an open diff, so if that's true, so if 
you go with the Redline, i belive you do not want the NS variant.  please 
check the spec's before you buy/try.

anyway, you can change the oil for just a few dollars, assuming you 
provide your own labor.

On Thu, 13 Jul 2006, j.koenig wrote:

> Speaking as a guy who's now replaced all four wheel bearings, I think you would tend to
> notice a change in the sound due to side loads (steering/weaving) long before you would
> notice throttle-induced change (if ever).  I'm no expert, but it sounds to me like a
> classic ring and pinion issue.  I hope I'm wrong.  Good luck!
> John
> ----- Original Message -----
> From: "Chris Newbold" <chris at newbold.org>
> Just shy of 65k miles, and I'm starting to notice a whine originating
> somewhere in the rear. The whine...
>  o is loudest between 65-70MPH
>  o is unaffected by gear: 3rd, 4th, 5th or 6th and the pitch is identical
>  o is unaffected by steering inputs
>  o is strongly correlated to throttle inputs:
>     - it stops if you gently lift and coast
>     - it stops if you dip in and accelerate
>     - it returns in steady cruise
> The only things which satisfy all of these observations are:
>  o rear differential
>  o center drive shaft bearing (do the B5s even have these?)
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