There is some confusion in the RWD market, where a lot of people think Diff = Final Drive, which isn't the case, so would like to clarify the terminology first.
Pumpkin: This is the whole differential unit, containing the differential and final drive
Differential: This is the part that we make i.e the LSD
Final Drive: This is the Ring Gear & Pinion, and is what makes up the "ratio". We will be making oem ratio final drives for those who have welded differentials. We are also thinking about making different ratio final drives for those who require better performance (whether acceleration or power rating). 4.75 anyone?
When you purchase an LSD from us, this only replaces the oem differential unit; you would still re-use your oem final drive.
For the non 135i/335i bolted diffs, if your current ratio is <= 3.07, you would choose the MT fitment. If your ratio is >= 3.15, you would choose the AT fitment.
All diffs for bolted ring gears are in stock and ready to ship. If you do not wish to wait, you can order directly from our website. If you want to save 20% and wait for the group of 5, please let me know and I'll add you to the lists:
135i/335i Welded Diff Update
We just managed to source an early model bolted large diff, so once it comes in, we can take our measurements and start producing the 3.08 and 3.46 final drives.
ETA is around 2-3 months. Once available, you guys will have the option of purchasing the final drives standalone (to use with another LSD), or as part of an "upgrade" option when purchasing one of our LSD's. Our option will basically allow you to upgrade to an LSD at around 1/2 the cost of what is currently available.
Alternatively, you could source the correct large diff oem final drives (a quick google search brings up a few options) and use that. This way, no need to wait the 2-3 months for our final drives, although you would be paying a few hundred dollars more for a used final drive rather than our new ones.
135i/335is DCT & 335d Models
We are still looking for a donor to loan us their pumpkin or diff & pinion for around 2 weeks. This will allow us sufficient time to take our measurements, and we can then ship back to you to minimise downtime. ETA for the LSD & Final Drives will be 2-3 months. The donor will receive an LSD + Final Drive free of charge when ready.