Hi everyone, I know that this has been discussed by many but I'm having some issues with what I thought was common knowledge posted on the internet.
I've been trying to build a set of axles for a late E21 LSD I've picked up (3.91:1, 10mm threaded holes on the flanges). I've seen quite a few ways to do this, from getting axle flanges redrilled to 8mm and using 5mm or 1/4" spacers, to swapping flanges, to drilling CVs out to 10mm.
The route I'm trying to take is one that I've seen posted more than once: Take a stock 2002 CV, a stock 2002 axle shaft, and a '79-only E21 CV, and build an axle which requires no drilling, spacers, or tapping. However, upon building an axle with this combination, I'm left with an axle which is roughly 1/8" shorter than a stock 2002 axle - I figure this number by taking the offset from the flange face of the midpoint of each CV. The CVs from the '79 E21 appear to be moved inward (toward the axle shaft) by about .150" when compared to the 2002 CV.
Now because the differential is about 10mm more narrow on the E21 compared to the 2002, this is obviously not ideal.
My understanding of this combination, and the reason I wanted to build them this way, is that the '79 E21 CVs are thicker by the correct amount to make up the distance that would normally be taken up by a spacer. But from what I've measured, this is not the case, and they are actually effectively shorter than a standard 2002 CV.
There are two possibilities that I can think of - the inner CVs I have are not actually from an '79 E21. I can't really verify this as I found them in a crate of misc. 2002 and E21 halfshafts, but they are stamped with "04/79" and bolt up to the differential I have, so I assume they are correct, but being that I've never seen any pictures or dimensions of these one-year-only CVs I can't be 100% sure. The other, more likely possibility, is that I don't like the data that I've collected and can't accept that something I read on the internet is untrue
Has anybody else struggled with this? I thought this would be a straightforward process but as I look at more axles and measure more dimensions, it seems like BMW changed something about the axles approximately every 5 minutes. I'll have some pictures up later today of some problem areas I'm having.