540iA differential upgrade

[kentish]

Hi to everyone,

I got a 540ia without limited slip. Would it be possible to upgrade it to one with LSD. From which E34 or E32 should I get my diff from. And how do I recognise a LSD diff and its gear ratio.


Kentish
540iA 1994

[BrianH]

You'll need a diff from an '88 750iL OR from an M5. The 750's ratio is 3.15, so it's only a little higher than your 540's 2.93. The M5 diff is 3.64, I think, so that would be a big change from your current ratio. For the 750 diff, you'll need to swap your 540's input flange onto the 750 diff. The M5 flange should bolt right up. Check out www.bmwe34.net for the full writeup.