Jayson77

The u-joint bolt is wearing on the case. Never noticed or heard anything while driving. Just replaced that sides trailing arm. Rebuilt because of a bad bearing and noticed this wear during the reassembly.

Is this from bad yoke end play?

69L88

Your profile says you have a 77 so you likely have badly worn stub axles, due to poor GM quality control during that period. The heat treatment of the axles during manufacture was not to design standards, resulting in softer axles. They rub against the posi cross shaft, which is a lot harder, and wear. You will need to pull the differential and replace the axles at a minimum.

Jayson77

Perfect. Thank you.

Jayson77

I may tackle this on my own. Just in case, anyone know if this wear would qualify as a bad core?

GTR1999

The amount of wear you have is close to the snap ring. If it's past the snap ring they're junk. Some will core and rebuild axles- buyer beware. Some use hardened tips - some of those are good if you know how to check them, otherwise.

You need to rebuild the diff. 77 also had bad ring gear bolts and clutches. Posi cases need to be checked.

Then you have the question of what axle will you buy, new or rebuilt? Issues with both. If you install a replacement axle and end up with 020+ endplay that's not too good. I set them for 005-007" that's where they should be.

69L88

Generally speaking, the short answer is likely no. If the differential is original, you actually have the best posi carrier among the 63-79 years they were manufactured.

Rebuilding these correctly takes a fair amount of specialized tools and experience. Gary Ramadei (gtr1999) is the best there is and is extremely helpful in guiding you through the process should you decide to go down that path. You can, of course, elect to swap it out with a “rebuilt” unit but you really need to know about the rebuilder and what they use for parts and what practices they employ. Most of these rebuilders don’t know how to/refuse to “tune” a posi and you may end up with a unit that is inferior to what you have now.

gkull

My 79 wore away my diff case in less than 50,000 miles. It was past the snap rings and totally trashed the rearend with metal in the oil. So I didn't even get a core charge return on a new diff. I ended up throwing it in the dumpster.

Jayson77

Was your wear similar to mine or worse?

GTR1999

I wrote this 15 years ago, it will help you check things. I wrote several how do threads over the years. Some may still be here they're still on DC.

https://www.digitalcorvettes.com/thr...pection.77316/

gkull

I had worn rings around the case from the yokes. Worse than yours. The company didn't want it because of the case damage. I probably should have installed all new internals and kept it as a spare.

Stormin_Normin

Both mine in my 77 were trash, I had vtec rebuild it for me and re-gear, Jim did a great job if you need a rebuilder in your state.

Jayson77

Was your wear comparable to the picture I posted?