Re: Advice on rear differentials!!

[Spiegelthal.Dave@xxxxxxxxxxx]

Ken wrote:
<Can someone please tell me what ratio diff. should be on a M3 E30 91
convertible and how can I identify that it is the correct one. I have just
had it replaced and it is making a muted roaring noise @ cruising speed that
is audible from the cabin which turns into a muted whinning noise @ motorway
speeds, it is bearable but is this normal? Does a LSD diff. make more noise
than a non-LSD diff.? Or could it be my rear wheel bearings?>

Be careful here.  I had the same sort of noise in the rear of my '91 318 sedan
(4.10 non-LSD), and I was 90% sure it was the rear wheel bearings.  Brought it
to my friendly local shop (who have been very good thus far, in my experience),
to have the bearings done; however, I did ask them to test-drive the car first
to confirm my guess about the bearings.  Lo and behold, they told me it was the
differential, and not the bearings.  So I ordered a used 325i differential (also
4.10 ratio, marked on a metal tag on the upper right side of the diff) from
Jason Lile at Zionsville Autosport, and put it in last week.  NOISE HASN"T
CHANGED!  Turns out my original diff (with 105K miles on it) was good all along,
and I was right about the rear wheel bearings!  So I'm now negotiating with the
shop that did the wrong diagnosis to do the rear wheel bearings (finally) for
free (although I'll give them my old, but apparently OK, original diff).  Thus
hangs a tale....  On the plus side, I now have a beefier 325i diff in my 318i,
and I can vouch that Jason Lile provides a good product with speedy service.

     Dave Spiegelthal
     Calverton, VA
     C

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