Fine bronze dust in diff oil

[Parazine]

The pinion assembly is the usual culprit in A7 diff demise in my experience, very often the lock nut on the thrust bearing is not tight enough, the bearing spacer then wears creating end float.

I agree with Ian that pinion end float is a primary trouble source in 7 axles but the question is: did the nut become loose or did the spacer wear first?

I think that previous drivers lack of skill with the clutch starts the rot, moving the train of bearings and spacers on the pinion. Once they start to move, the soft spacer wears rapidly and terminal end float sets in. This is apparent from the original axles I have stripped, where the nut is still tabbed up from the factory but not actually doing anything.

The same issue appears to afflict Big 7 axles, due to the fact that there is no engine rear oil seal and the crankcase can vent oily fumes into the bell housing. These condense on the clutch plate, causing horrendous juddering when combined with metalastik engine mountings. The back axle is the casualty.....