I have been sitting on a 4.1 ring a pinion set for almost three years. And just a few days ago I was lucky enough to find a cheap rear diff that would let me attack the rebuild and gear swap without having to first take the diff off the car and decomission it for who knows how long.

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An interesting surprise happened when I openned the differential only to find a V2 unit. The intent of buying a spare one off an e46 M3 was to get a V1, what were the odds to get one of the last ones :S


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I will try to document the process, but only those things that are really worth or for which there is not a lot of data on the net. There are several videos, but sometimes there a key details that are not mentioned or explained in detail.

Taking the diff apart is not difficult, and there is really not a lot to say as the videos we there are already explain this well enough. I will list the videos that I think are the most useful to tackle this process

Latest videos from racing diffs explaining their rebuild kits

V1 - https://youtu.be/RlqnD7k2HMU?si=oTM9VWwIc4VCPuNV
V2 - https://youtu.be/2G8PTSL4lrg?si=Xyc7-ThBcqA6Gyd1

Now here some documentary videos I have found extremely useful

From our fellow member created:

Nuances when ordering: https://youtu.be/8cRbYSChJkY?si=RIilO2N2QDLSsy13
Rebuild V1: https://youtu.be/G9pUsKDc5iE?si=YAfm--v1UMJH7XFS

Rebuild videos from racing diffs
V1 - https://youtu.be/F7QTGKCcWVU?si=fmOTr6WWLOgeX7vd
V2 - https://youtu.be/Bwtnud_ObwM?si=0EFIVfL1ft_3zKt8
Gear Swap - https://youtu.be/qt2OmQMT_l8?si=pyIYXnmR-GcGcd9J

Rubuild video from YEVS builds
V2 - https://youtu.be/jd3d0EqjBR8?si=s8Nixa-Yfj1auQzT

Now, since I am limited in space and tools. I am buying tools as I go, but my approach is to buy those things that will really make the rebuild process smoother and easier.

One thing I will for sure try is a pinion bearing puller.

Bearing puller tool - https://youtu.be/xtxgtDX7M8E?si=nyAd7_J1bFbrM6em

However, the V2 design is already making me doubt I can use the tool, in which case, I would just return it if I cannot make it work. The issue is that the V2 output flange bearings have very little space to use this tool, and for the pinion, well I am chanign to a new one, so if I still need to cut the races off to swap the bearings, I will return the tool.

Bearing puller tool - The next tool is a time-sert kit, my spare diff came with that bolt hole stripped!!!