1979 Jeep CJ7 304 3SP Manual rear axle assembly

[Chris S]

Recently my rear differential went out, along with that my rear driver side axle rod started working it's way out. With closer inspection the bearings seem to have been destroyed and not sure the level of damage in my differential. This is an original AMC 20 rear axle. I don't off road it so I don't need to over do it on the strength of the assembly. I just want it safe. Question is would it just be better to have the differential rebuilt and axle rod replaced? Are their aftermarket rear end assemblies that are bolt-on or do they require some level of fabrication? It's hard to find mechanic in my area that can do this work or want to do this work. I also having a hard time finding a used one to just swap it. Anyone have any ideas that won't break the bank? I'll probably sell it once it's safe to drive. Thanks 

 

[Moses Ludel]

Chris S...See my comments below...Welcome to the forums!...Moses

8 hours ago, Chris S said:

Recently my rear differential went out, along with that my rear driver side axle rod started working it's way out. With closer inspection the bearings seem to have been destroyed and not sure the level of damage in my differential. This is an original AMC 20 rear axle.

If your axle housing is okay, the AMC 20 is actually a bigger ring gear diameter than a Dana 44 (8-7/8" versus 8-3/4").  This can be a very durable axle.  The question is the extent of damage.  You'll want to inspect the axle housing and axle bearing area to see whether the axle shaft breakage or loosening damaged the housing bore where the axle shaft's outer bearing rides.  

If the axle housing's center section and ring-and-pinion gears are still okay, a differential carrier/case change and differential gears might do it.  If the ring gear is okay, the differential carrier/case can be removed, keeping track of the shims and where they go.  (Both axle shafts must come out to remove the differential and ring gear.)  It is possible to realign a ring-and-pinion set if you have kept track of the shims.  The pinion gear can stay in play unless the pinion bearings need replacement.  Replacing the bearings and seals would be part of a complete rebuild, but if you are on a budget and the pinion gear is okay (no noise before or after the differential breakup), the pinion shaft and driveshaft can be left in place for repair work on just the differential.

I don't off road it so I don't need to over do it on the strength of the assembly. I just want it safe. Question is would it just be better to have the differential rebuilt and axle rod replaced? Are their aftermarket rear end assemblies that are bolt-on or do they require some level of fabrication?

If you simply want to restore or repair the axle, do a close inspection to make sure it's repairable.  Many owners opt for aftermarket one-piece axle shafts to eliminate the factory two-piece design.  That might be smart, especially with the one axle shaft already broken.  As for a swap axle, again, the common consideration would be a Dana 44, but that is really no stronger nor more reliable than the AMC 20.  The only weak link with the AMC 20 is the two-piece axle shafts.

It's hard to find mechanic in my area that can do this work or want to do this work. I also having a hard time finding a used one to just swap it. Anyone have any ideas that won't break the bank? I'll probably sell it once it's safe to drive. Thanks

If selling the Jeep is the goal, I would repair the differential as long as the ring-and-pinion gears are okay.  Consider the one-piece axle shafts or price compare them with an original equipment two-piece axle shaft and hub.  This really comes down to what is currently damaged. 

Can you post some pictures of the axle damage, including the axle end where the axle shaft came loose?  I'd like to see the extent of the damage.  If you have the differential cover removed, send some photos of the axle center section, ring-and-pinion gears and the differential case and pieces.

If you need more details on the AMC 20 axle and one-piece axle shafts, we have covered this extensively at the forums.  Do a site Search under "AMC Model 20", scroll down, several topics are listed.