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RE: E-30 e differential Q's



> My differential is deginning to contribute to the background noise
> at highway speeds and when driving around town. About 8 months 
> ago I replaced the oil with Redline diff. oil,

Josh,
	That (Redline) is the main cause of your newly discovered
differential whine.
	I went through a similar exercise a few years ago on my '89 325i
(with 3.73 LSD). Redline 75W90 oil was too thin for my 100+K differential.
It was always noisy and emitted hair raising screatching in tight radius
turns. Corvette LSD additive (~$5 from a Chevy dealer) helped some. Mobil
80W90 rear diff oil helped even more.
	I can still hear my differential, but a). it is now tolerable; b).
they all do it; c). they all do it for well over 200K miles before you need
to worry about it; d). above 70mph the wind noise totally drowns out the
differential whine anyway.
	Read more on the subject at the BMW FAQ:
http://cbsgi2.bu.edu/bmw/FAQ.4

> Does anyone know the original stock diff. ratio for an '86
> 325e? I haven't been able to find anything like a tag on the
> differential itself to identify it.

	Your eta probably has either 2.91 or 2.93 rear differential (don't
remember exactly).

alex f

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