Diff legality - '95 M3 3.15

[tomfree]

As Sean builds my car, I'm doing what I do best...buy stuff. I'm looking at a 3.15 LSD out of a '95 M3. I know the input and output flanges are different, so assuming that we swap the flanges off of my 3.15 open diff, is this a legal diff for Spec3?

 

From what I can tell, the guts of the diff are the same between the M3 and the cold weather package 325i LSD, but I've been lied to by the intarwebz a few times in the past.

 

Thoughts and comments?

[Scany]

Technically it would be wrong since I belive the rules mean the diff available to the 325 from factory, but if it is the same (I don't know) I doubt anybody would care.

[tomfree]

Thanks for the reply, Anders. I've continued to research and read, and the information is consistent about the diffs. The M3 diff and the 325i/is cold weather package diffs are different part numbers, but are internally the same. I think I'm going to pull the trigger.

 

That being said, if it comes out later that this is not an allowed swap, I'll source a 325i/is diff before the car is raced...and that will be a while.

[MDizzle]

I think you're fine...diff ratio and lockup are legal...

[tomfree]

I think you're fine...diff ratio and lockup are legal...

 

That was my thought as well. Sean picked up the diff from the BMW farm last weekend and swapped out the input and output flanges. It's the right time to do all this, as the rear subframe is out of the car to weld in the reinforcements.

 

Thanks for the feedback.