I've been trying to figure this out for a long time now. Here's the quick rundown. It's a 1995 Miata, the diff is from an 86 RX7 non-turbo. I rebuilt the differential with some new parts from MazdaTrix and the pre-load is set to 75lbs ft.

The backlash is perfectly within spec, the bearing preload is within spec, and all of the bolts were torqued perfectly when I put it back together.

I'm using the axles from the 86 RX7 differential with new RX7 axle clips. I've also replaced the axle seals twice.

I still can't figure out why it's leaking. If you have any input it's greatly appreciated!

Here's my video: http://www.youtube.com/watch?v=j42iad_4ce0

 

pull the diff out, and pull it apart again. something isnt right. the axle shouldnt move like that

 

how is the gear pattern? is it too far on the heel or toe side? it's weird how only one side is moving excessively, seems like the diff is too far off to one side which is enough to lock one stub in place but not the other.

i don't think it has anything to do with the differential itself, just the install into the casing.