Crushing the pinon crush bushing - Special Tool?

[cek]

I'm in the process of making one good 3.25LSD out of two other diffs. I've never torn down and re-built a diff before, but I found excellent documentation here:

http://www.bmw2002faq.com/_/technica...tial-build-r74

I've got all the races in, new seals, and am ready to tighten down the pinion nut in order to correctly crush the crush bushing (I bought two because, apparently, I *will* screw it up the first time).



When I pulled the diffs apart, getting the pinion nut off was easy with an impact wrench. However, I can't get the input flange to be secure enough to support the torque required to turn the nut and crush the bushing.

I've looked all over for any documentation of what the "BMW Special Tool" (apparently called the "Final Drive Work Fixture"). I don't know what it looks like or what it's part # might be. I'm hoping I can either borrow something from someone or or fabricate something.

Anyone?

[cabriodster87]

Take some flat stock and make a spanner to hold pinion input flange, done deal.

[cek]

Take some flat stock and make a spanner to hold pinion input flange, done deal.

A long spanner won't work. The amount of torque required to crush the washer is large and I think the pinon nut needs to be secured to the diff case. I tried to use one of my M30B35 to E28 intake manifold brackets it just bent like it was nothing.



If I had some good steel stock around I could weld something up, but (a) I don't, and (b) I really don't know how to weld (yet).

[LJ851]

A long spanner won't work.

Yes it will, you are doing it wrong.

[Wanganstyle]

A long spanner won't work. The amount of torque required to crush the washer is large and I think the pinon nut needs to be secured to the diff case. I tried to use one of my M30B35 to E28 intake manifold brackets it just bent like it was nothing.



If I had some good steel stock around I could weld something up, but (a) I don't, and (b) I really don't know how to weld (yet).

1.Buy a thick piece of steel stock.

2.Make template of 4 bolt flange with cardboard + sharpie

3. take steel stock to drill press and drill your holes for the fixture.

4. crush that washer.......slowly

[AndrewBird]

I'd use a 1/2" x 3/4" bar, drill two holes in it the distance the flange bolt holes are, then bolt this to the flange. Get someone to hold it while you turn the nut.

[Zreberlcoe]

If you have access to an impact, my teacher taught us to use an impact on the pinion nut just until there's no in/out movement in the pinion flange. Put some gear paint on the the ring gear, spin the assembly around several times and check your pattern and report back.


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