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Re: differential questions (archive)
[ Follow Ups ] [ 5-series (E12) Message Board ] [ Msg. Board FAQ ]
Posted by WH on April 12, 2001 at 10:41:31:

In Reply to: differential questions posted by stewart on April 11, 2001 at 11:35:36:


If I go to a 2.93 rear end how will it affect my top speed. I have a standard 4spd w/ a 3.45. I've heard of a web site that can calculate this automatically.
thnx

If you want to change the rear diff instead of the 4 speed tranny to have nice hwy crusing, use a 3.07 rear end not the 2.93.

Most euro spec M535i's w/CR tranny (1:1 ratio same as the 4 speed) used the 3.07 rear end. It gives the same nominal ratios as a 5 speed transmission and a 3.45 rear.

Only the Alpina B7 turbos used a 2.93 rear, simply because they had the HP to use it. The 3.07 would run out of steam at around 140 so by switching to the 2.93 the top would be 155mph.

BTW where would you find a 2.93 rear end? 3.07's are fairly easy to score out of a 635csi, but NO standard production E12 based car I know of came with a 2.93.... only the Alpina's.

The later 528 eta cars hav'em but their diffs are not directly interchangeable with a E12.

WH

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