Thread: Cannot get the diff back into the axle

Rear diff was getting a bit noisy, so I reconditioned a spare I had lying around with the intention of swapping it over (so the vehicle wasn't off the road for more than the 30 minutes it takes to swap the diffs out).

Anyway, the old diff came out a little hard, but I didn't think anything of it. Cleaned up the old gasket gunk, went to install the new one and...

The blasted thing simply will NOT go in. I tried for a good hour or so, but it got to the point where the RTV dried and I had to abort the mission.

I've got a couple of new gaskets and decided to have a go dry-fitting it (i.e. no gasket) but it still isn't cooperating! Spent another hour or so today offering it up, jiggling it this way and that, lightly tapping it - nothing. Doesn't even get to the point where the gasket mating surface meets with the bolts. It seems to be something internal, so I've got no chance of seeing it especially while holding up a 20kg differential.

The weird part is - the old one goes in OK! A little jiggling needed but not too bad. The part numbers are all the same, I've triple-checked nothing is sticking out (with particular attention paid to the retainers for the serrated nuts). The spare diff came off the front axle recently, so is known-good.

Anyone got any ideas? When I did the front recently it wasn't nearly this bad. I noticed that the bolts inside the axle housing were rotated slightly, so that the "point" of the head was peeking out from the inside of the case slightly, protruding into the opening for the diff. No idea if that matters. If you've got any experience with this at all, please chime in - I'm pretty stuck right now.

Thanks for the input guys.

Gippy - that first photo is interesting, it has the bolt heads protruding into the opening to about the same degree that mine does.

I had a look for burrs etc, and filed off some minor ones on the locating dowels (my rear axle has two such dowels for some reason). Didn't make a difference, but I did notice something - the retaining wire for all the bolt heads was broken on both sides!

There are two wires, one each side of the ring gear cutout. I've removed it but ran out of time last night to try dry-fitting the diff again, I'll give it a shot tonight or Saturday.

But I reckon it's pretty safe without the wire, right? The bolts can't work their way out because of the head, and they can work their way in but that would tighten the nut on the outside. The only risk is when installing the nuts, and some Loctite would sort that. The wire feels a bit "belt and suspenders" to me.

Anyway if it still doesn't work after removing the broken wire (perhaps it was getting hung up somewhere) I might dremel off the protruding corners of the bolt heads. Feels a bit "farmer fix" to me but I don't think it'd stop anyone removing them in future, and presumably there's a reason the 2A diffs went to studs.