1988 325i SE Coupe - Differential ratio.

[kevin_whittaker]

Sorry for asking another stupid question, I have removed the rear end from my E30 to cut out and repair the rusty bits, it is all stripped down for painting and overhauling and the rear differential is leaking and is a little noisy, so I intend to replace it - so can someone help me to identify the correct ratio?

There is a tab under one of the bolts that reads 373 5291 - does that mean that it is a 3.73 or are I missing something elswhere??

Thanks in advance everyone.

[B7]

Yes, you have a 3:73 ratio'd NON limited slip diff.

[kevin_whittaker]

Thanks mate, kind of what I thought but I wanted to check before I went looking for a replacement.

[B7]

Theres 3 ratios you can take a pick from

What you have a 3:73 which it appears (in the cars I've seen) to be 325i Auto spec. Also the choice for Alpina on the C2 2.7's

A 3:64 which is usually a manual 325. It's a bit longer so drops the revs at speed which improves economy. Stats will say it'll blunt the performance but I'm damned if i've noticed much difference in my convertible.

A 3:91 which was touring fare I believe and also the ratio of the LSDs in tech 2 sports. The revs will rise at the top end but the performance will be noticably more sprightly but all at the cost of fuel economy.

You really decide what the cars going to have to deliver for you then pick the ratio really.

[kevin_whittaker]

Thanks for the information - I will keep my eye out for a decent replacement. The differential currently in the rear end of my E30 is a bit noisy, I suspect that it has been run without/low on oil in the past...

Appreciate your time responding to my question.