E28 differential upgrade??

[TomsD2]

I have a 1985 535i with 5 speed and wanted to upgrade the differential to a 3.73 ratio limited slip. I bought a 1989 E30is auto transmission, 3.73 limited slip differential. Got the differential in, pulled my old one out, swapped out the rear cover with new gasket, and tried to install it.

It seems the axle flange bolt pattern is different (less distance between bolts on the E30 versus my E28).

I'm not totally sure, but the upper mounting bolts seem to be slightly different. The lower mounting bolts seem to work good but the two bolts on the top of the case don't seem to align. Of course this may be my frustration with the axle flange issue.

Anybody familiar with this swap?? It was recommended in the tech section of the Roundel a year or so ago and it was made to sound like it was a bolt up and drive conversion.

What are my options?? I would really like to keep the differential but if the mounting pattern on the case is different as well as the axle flange, I may be hosed.

If the case mounts are ok (and I just got to pissed to fight it) then it looks like I either have to swap over the differential axle flanges (will that work?) or have some E30 C.V. joints installed on the differential ends of my axles.

Any help greatly appreciated!

Tom
1985 535i
1995 M3
1947 Caterpillar D2
1950 Case LA

[shawn_d]

... post in the right forum -- the technical forum, not the "lounge" (which is what we're in).

Step two -- swap out the rear cover and axle flanges with your E28 parts. The cover is obviously bolted. The axle flanges merely pop out.

See -- posting in the wrong section got your question answered in a "quick" month and a half! :D

[juan-O]

shawn, call me about the arian nation meting asap.

[gsuffa]