A Few Diff Rebuild Questions, Crush Collar?

[Blackmk3]

So decided to finally strip my spare diff apart and rebuild it, bearings have lots of play leaking axle seals etc just age

The car is a 1989 ma70, Ive got the LSD side sorted (dealt with that before) but just a question, ive been searching around and researching the "Crush Collar" that seems to be pointed at many diff failures in our cars

After talking my diff all the way apart, Pinion out etc. Theres a metal sleeve that sits between the two bearings on the pinion so when you tighten up the pinion nut then presses on the bearings, hence pre-load

Correct me if im wrong but i was expecting some sort of rubber device or something that fails over time, but how can this metal sleave cause this problem? in theory unless the but comes loose it will stay like that? the aftermarket kits available are just aluminum versions?

I cant seem to find any pictures around or anything to run off

Just wondering if somebody can clarify this for me, Im going to throw some new bearings and seals at it with a shimmed up stock LSD, which will be fine for my use

Thanks
Nick

 

[IJ.]

It compresses further under power/load and you end up with play.

 

[Blackmk3]

Right so under load it squeezes one bearing and the other looses its pressure and gets play?

i understand now, so by a custom spacer and shims you can set the preload and it wont change, under load

 

[IJ.]

It actually crushes more and you lose preload.

 

[supraguy@aol]

I'm pretty sure that all the aftermarket upgrades are steel, not aluminum.
The included spacers are used so that you can set the proper preload by incrementally adding to the collars effective thickness(trial and error) till it is correct.
It takes a bit of assembly/ disassembly, but you eventually nail it.