LSD/gearbox preload procedure

[str160]

Hey folks,
Does anyone have a link/copy of the procedure for preloading the bearings when installing the OE LSD?

I'm going to take the LSD out of the 5 speed box and put it into the Celica box whilst I have the engine out again. Can't find a single thing online showing how to do the preload.

Thanks

[lamcote]

Is this any help?

 m https://www.miata.net/garage/diff_rr.html m

Or is it just the gearbox bearings you mean?

[str160]

No, don't think that is what I'm after.
I've read that the LSD needs the bearings preloaded during installation. That's all I can find out.

[jonbill]

The bearings aren't preloaded before installation - the preload refers to how hard the cups are pressed on to the taper roller cage by the case & shims they're installed into.
I've not done a transaxle, but this photo of my datsun diff shows the side bearing & shims held in the case. I'm sure the mr2 looks different but I expect the principle is the same.

So the preinstallation bit is about figuring out what size shims to use. In my (very limited) experience, the diff units are very consistent in size and the cases more variable, so you can often replace the diff in a case and just use the shims you had before.
The post installation measurement of preload is the torque you have to apply to the pinion to get it to rotate. Normally a very small number, like 10 in lb. (which is the sort of force you can apply with just your fingers). I don't know how the pinion is presented in the transaxle to measure but I guess it'll be obvious when you're in there.
In the ones I've done I didn't measure it with a torque wrench - they're not easy/cheap to get at that low range so I settled for it being stiff to turn with my fingers [emoji3]
Of course, it could all be different in a transaxle!