I know its been a while since my last update, but the 3.91 215K E53 X5 diff did not fit as-is, turns out the front diff mounts were 35mm too far forward which means that it could not be physically installed on an E8x/E9x rear subframe. So I bit the bullet and ordered a shim kit from Mfactory to install the 3.91 R&P onto my existing carrier - install was pretty straightforward and I ended up with a good contact pattern and 0.006" of backlash, right in the middle of Mfactory's recommended spec. I also machined the backside of the ring gear to remove rotating mass, and ended up shaving 0.35kg without weakening it at all. I could have sworn that I took pics documenting the process, but I can't seem to find them anywhere... :/
I then decided to further complicate my life by installing a 1M transmission (13kg lighter + the best shift feel I have ever experienced) along with an M4 CF driveshaft. Transmission install was pretty straightforward as it is a PnP proposition provided you use the matching shifter parts, the M4 driveshaft - on the other hand - was anything but. Required a LOT of careful measurements as well as cutting both ends as neither bolt on, so I had to use the front guibo/yoke off an N54 driveshaft and the rear CV joint off an E53 driveshaft. I'm proud to say that the end result came out looking factory...
Before:
After:
On the car (finally!) :
And finally, some gratuitous rear-end shots thrown in:
And finally, GS6-45BZ & GS6-53BZ side by side:
PS - Don't ask about the hammer
I then decided to further complicate my life by installing a 1M transmission (13kg lighter + the best shift feel I have ever experienced) along with an M4 CF driveshaft. Transmission install was pretty straightforward as it is a PnP proposition provided you use the matching shifter parts, the M4 driveshaft - on the other hand - was anything but. Required a LOT of careful measurements as well as cutting both ends as neither bolt on, so I had to use the front guibo/yoke off an N54 driveshaft and the rear CV joint off an E53 driveshaft. I'm proud to say that the end result came out looking factory...
Before:
After:
On the car (finally!) :
And finally, some gratuitous rear-end shots thrown in:
And finally, GS6-45BZ & GS6-53BZ side by side:
PS - Don't ask about the hammer