pharmed said:
What's the approx cost of this? Considering you can now buy a £600 LSD diff is this project still worth it?
Depends on:
1- what you want
2- what you can get the M3 diff for
3- how much you can do yourself
For me:
1- I wanted the 3.64 gear, the larger/stronger diff (to deal with the LS7 swap), and wanted to run Porsche brakes front and rear.
2- I was able to purchase the entire M3 diff (with brakes) for $800 (£471).
3- I was able to do the entire install myself (zero install cost).
By contrast, the Z4 188mm LSD would have cost me over $1000 and I would have needed to pay someone to install the LSD into the diff (so $1500-$2000 in the end). For me, the M3 rear end was hands down the way to go. I plan to convert my wife's 325i to an M3 diff some time in the future.
For others who can't install the rear end themselves, don't need the extra gear, don't need extra strength, and/or don't care about larger rear brakes, the Z4 188mm LSD is probably a better option (most cost effective).