38 Cadillac differential question

[cadillac60]

I have noticed some oil leaking from the differential at the drive shaft connection. What parts would be required to stop the leak & would it be a job where the rear axels would have to be removed.

Bruce W

[Tom Beaver]

Bruce, you most probably just need a new oil seal and possibly a repair sleeve for the yoke if it's seal surface has been worn by the old seal.  The repair only requires that the drive shaft be disconnected at the differential and that the differential yoke be removed from the pinion gear shaft.  There are two different size seals available for the differential depending on whether or not you have a sheet metal spacer/seal retainer installed.  I don't have the seal part numbers written down but if you remove the old seal and take it to an automotive parts house or bearing supply store they should be able to match it.

Tom Beaver

[47bigcadillac]

Make sure you mark the pinion nut position (angle) on the pinion thread- It will be a lot easier to tighten it back and get it close to the original bearing pre-load.

Usually it needs to be tighten back with 1/4 turn further in, to avoid gear grinding.

Too much tightening may destroy the bearings - its safer to have it a bit looser and then drive the car, coasting at speed to listen to any gear grind when releasing the throttle, which is quite easily noticeable, and then minimally tighten the nut bit by bit (like 1/8 of a turn) until then noise is completely gone.

Also, you definitely need to either put Loctite threadlocker on the pinion thread or use another method to lock the nut, since the nut will quickly get loose driving, when the old crush sleeve is re-used.

I used steel wires hooked to a cut-off  32mm metric socket in order to anchor the nut to the yoke, without having to resort to thread sealant (see photo), on my 1946.

If your pinion seal is in the "Seal holder cup", It will be quite tricky to remove the holder without destroying it ...you may have to build a small tool which attaches to a pull hammer to remove it as the edge/pinion shaft gap is quite narrow.

[joeceretti]

Very intelligent solution, I must say.

[Steve Passmore]

You need to know what series car Bruce has before you go frighting him with talk about Crush Sleeves. There are three different types of axle in 37-38 and the smaller series were not using crush sleeves but a solid sleeve held under pressure from three external bolts on the casing.   The rear flange nut has no bearing (if you excuse the pun) on bearing pre load.