My '81 had about 85K miles on it 8 years ago when I started the rebuild. (Yep, 8 years ago I started taking it apart and am just now down to bare frame but that's another story)

I've posted some pics of the diff here: http://home.tampabay.rr.com/jking13/myvette/default.htm

My question is how do you know if it needs to be rebuilt or not? I had only driven the vette about 3 times before I started taking it apart and it didn't run that great back then so I can't recall anything about the tranny or diff that would be helpful. When I opened it up it looks great so far as I can tell for being 25 years old but I admittedly don't know a whole lot about differentials.

Looking at the unopened/uncleaned pic of the differential, it looks like it may have been leaking around the yokes. Can just the seals be replaced? If so, what kind of work is involved in doing so? Is this a job that can be done at home or should it be hired out to someone with the right tools? I'm apparently slow at the restoration process but am competent at working on mechanical things provided I have the right tools. I have more time than money so if I can do it, that's what I would prefer but would rather the job be done right the first time. Thanks for any input!

 

if you want done right, the man for the job is gtr1999 i think is his sig... he'll chime in i'm sure cuz he's the expert on diffs on this forum

 

You can replace just the yoke seals. You have to remove the circlips from the axles, pull the axles out, knock the seals out and drive the new seals in. Ideally, you'd want to use a seal driver but you can drive the seals in with a flat item that is a bit larger than the seal diameter.

The hardest part is getting the circlips back on the axles. It just takes patience.

If the front seal is leaking, that take a bit more expertise.

 

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If you have a Harbor Freight store handy, you can get a seal driver/bearing race installer kit for short money.

 

Good to know. I'd like to do all three while I have it out and apart. Anybody out there done all three? Has anybody taken pics of the process and know what else is required to do the front one?

 

I love Harbor Freight for certain things. This sounds like a good time to visit them and pick up a tool or two. Thanks for the heads up.

 

Been through this with my 80. There are a few things to look for, but given that yours has only 85K on the clock I wouldn't be surprised if it's mostly fine. Apart from changing the seals as you mentioned, other things to check are:

Ring-pinion backlash - should be .007" or thereabouts, check the service manual

LSD clutch torque - this is the torque required to rotate the side yokes relative to each other. Grab one yoke in the vice and rotate the other, see what torque it requires to do this. There's no spec in the '80 service manual for this, but I'd expect it to be 40-50 ftlb region. It's probably more for new clutches. If it's not hard to rotate the yokes in this way, the clutches are worn. You need a special tool to get these things out.

Also check the condition of the retainers on the "ears" of the posi-clutches - these take a hammering and might well be broken, allowing the clutches to rotate and cut into the carrier. Seen this on both of the 80 diffs I've opened up, so I think it's a common problem. Again, to replace these retainers requires removal of the clutches, which is a bit if a pig, and needs a special compression tool.
Obviously check the condition of the gear teeth -pitting, burning, wear etc.
Centre pin- should be free from excessive wear. If this needs replacing, the ring-rear must come off to clear the way, hence the carrier must come out and you should use new ring gear bolts when putting it back together.
Yoke inner ends - should have no more than 10 to 20 thou endfloat on the yokes, again no actual spec but this is a good figure when you consider the yoke end float dicates the suspension geometry via the halfshafts. If there is excessive float it's either worn yoke ends or centre pin.

Hopefully the bearings should be in a pretty good state - unlike the earlier vette diffs, you CAN remove the pinion to have a look at the condition of the pinion bearings, without messing up the pinion pre-load. The older ones had a crush-sleeve as a spacer, the dana 44 has a solid spacer, so you can remove and reinstall the pinion as much as you like, as long as you use a new nut each time! Makes replacing the pinion oil seal relatively easy.

Unless the bearings are totally wasted, I'd avoid replacing them unless you want to spend ages re-setting the contact pattern and bearing preload. Again, you'll need more special tools for this.... more of them than with the 79-back version.
Like some other people mentioned, Gtr1999 is the resident expert on these diffs, and hopefully will chime in with some advice...

 

 

If you do a search of the threads started by Gtr 1999 you will find one that will show you the complete process for rebuilding the rear end.
Good luck!!!

 

I should have said that!
That would probably be the best info I could have given
Although, Gary's paper is aimed at the 79 and back, cast iron diffs. The dana44/80-82 is a little more fiddly to do properly, ie if the posi clutches or bearings need replacing - more special tools needed! I did start a 80-82 rebuild paper myself, but just haven't had the time to finish it yet....