Just came in to check the Mini thread after rebuilding the TA03 ball diff in my M03 LWB. A huge contact with a board required the replacement of a front chassis half, so it seemed like a good idea to redo the diff since it was built over a year ago.

I posted how to build a TA03 diff awhile back so won't bore anyone with it. Just want to say that the diff was still smooth, but I wanted to tighten it a bit. What I found in the teardown was that the diff rings showed almost no wear and just needed a touch up with some 600 paper and a quick buff with some polish. What I did find was that one of the large Belleville washers had "flattened" and needed replacement. That was why the diff seemed looser than my others.

As Craig said, attention to detail will pay off----also good driving. The M05 diff is "tricky" to build correctly and little stuff can really trip you up. As I recall you had to flip the diff over halfway thru the build to get everything in the right places. Lapping and polishing the diff rings should help keep the diff smooth much longer than stock. Ceramic diff balls are a good investment cause you don't have to replace them every time you rebuild the diff. It's actually cheaper.