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What makes a differential unable to be rebuilt? Mine has the usual stub axle wear. Mine are so far worn, the U bolts are contacting the case. Does that mean anything in terms of being a rebuild candidate?
I would jack it up and see how much that yoke moves in & out.
It is important to measure it too.
As it moves out, look at the yoke seal surface and see if it looks damaged.
If the seal area is damaged enough, the entire outer diff housing is junk.
But yours does not look like an oily mess, yet, so you may be in luck.
What makes a differential unable to be rebuilt? Mine has the usual stub axle wear. Mine are so far worn, the U bolts are contacting the case. Does that mean anything in terms of being a rebuild candidate?
To really answer your initial question, you’d need to fully disassemble the unit and take stock of all of the parts. In most cases, all parts can be replaced but you need to be clear in your objectives and balance the cost and level of effort needed to achieve them with what you have.
Your stub axles are likely toast. In theory, they are rebuildable but you need to be very careful about confirming what you get are getting is acceptable in therms of quality. Check the posi case carefully for cracks as that is a common problem. If cracked, they are junk. Don’t let anyone tell you they can be welded. Quality gears for these units are very, very difficult to find.
Bearings and seals are readily available (use Timken bearings).
Check the rear cover carefully for cracks. Muskegon brake sells a replacement heavy duty cover.
Building these units correctly takes a lot of knowledge. There are many rebuilders who will offer up a “rebuilt” unit but you get what you pay for. Caveat Emptor.
The axle already has hit the differential ear, if the lip is ground away and the seal hit you have a doorstop. I can machine repair an axle bore but it's not worth it.
The fact that the axles worn that much indicates they are probably the originals and that usually means the internal parts are probably worn too. Not always to the point of junk but no one can tell you what you have until it is taken apart an inspected correctly. Buying a common exchange diff- no comment.
You need to pull the diff, and then the back cover to inspect. Then pull the c-clips and the axles.
Then you will be in a much better position to determine how much of it is still good.
Visual comparison pics below:
Axle seal area on diff case. This is what you DO want to see. No rubbing marks, both case lip & seal intact. The lip on the case is raised somewhere around 1/8" or so where it holds the seal. Because your bolts hit the ears at the bottom of the pic, you are very close to damaging this lip.
Axle stubs. Good ones on the left measure 0.185" c-clip groove to tip, and have a beveled edge. Worn ones are on the right. Sometimes they go all the way down to the c-clip. These were almost there. I'm guessing yours will look bad and need replacement because the bolts hit.
Main gears. Hopefully they did not whine or make noise. Then likely the main gears are still good. Unmarked gear teeth is what you DO want to see. A very smooth shiney surface.
Posi case. This is what you do NOT want to see. Spray the grease with brake clean and look carefully for cracks, especially near all the windows and the pin hole. The pin should fit pretty snug in it's hole. I went thru 3 cracked ones before I found a good used one.
If it passes visual inspection then the main parts are likely good candidates for a rebuild.
If you want, post pics like these and then the CF can help.
Last edited by leigh1322; Sep 15, 2023 at 07:47 PM.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
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Ou need a new one.....i have found decent ones on FB market place or here on the forum. Decide what you want for gearing and stay with that choice....another is to either buy a rebuilt from Gary or from one of the reliable companies like Duntov or Vansteel..etc..
Gary "mentored" me when I did my diff myself.
I could not have done it without him.
So I feel it is my obligation to help spread the knowledge, and help him by saving him some time replying to so many inquiries.
At least questions that I feel comfortable with.
But he has forgotten more than I will ever know.
He's the real expert.
Diff rebuild or replace
