I have a 77 stingray.. It seems that the snap ring for the yoke coming out of the right side of my rear end may have sheared off.. broke, came off.. what have you.. Its no longer holding the yoke into the rear end.. The yoke doesnt come all the way out but it moves freely in and out about 2inches when i turn corners. Now i have stopped driving the car. I have it up on jack stands with the back to wheels and spare off. I cant for the life of me figure out how in the hell to open the rearend case. Usually i am pretty good at figuring these things out but this is my first corvette and i am seriously at a loss.. If some one could maybe point me in the direction of a build sheet or break down manual i would be ever greatful. I have the "Haynes Repair Manual" for the C3 but there is nothing in it about the rear end... Now all the parts appear to be orignal or at least factory replacements, nothing appears to be out of the oridanary. But i cant figure it out lol.

Fellow corvette guy in need.
Bones

 

Bones.
Most likely the tip of the stub axle is worn off past the snap ring groove. The stub axle won't come out because the end of it is mushroomed. It will have to be ground down to remove. The Haynes manual won't help you much. The differential has to come out and be dis-assembled if nothing else to remove the metal that has accumulated in the cavity between the pinion bearings. You also need to inspect the case at the seal for damage from the stub axle moving in too far.
Mike

 

I have a 81 and i know 77 are diferent but remove the spare tire holder. Take out the bolts that hold the rear diff cover. You should see the internals of the diff at this point. You may be able to put a new retaining ring on fluss the rear and be good to go.

 

The C3 diffs may have a 'cover', but that 'cover' supports the entire center section to the frame and the transverse leaf spring. The differential side yoke that you say moves out, should only barely move in and out by .050" (less than a 1/16th). It forms one element of your rear suspension geometry, along with your lower strut rod. More than likely the end of the yoke has worn away, taking with it the snap ring groove meant to keep the axle in when the body rises relative to the road surface (high crowned road at speed, on a lift, etc.) to maintain correct rear alignment.

I rebuild these diffs regularly at a shop in Linden, NJ. Don't, I repeat, don't buy a cheap repro yoke, they are junk. Spend the $150-200 for a good one, typically a rebuilt GM with tool steel button to replace the worn-out portion.

And it is likely the other side has a problem too. They only wear out when one rear axle/wheel spins faster that the other (tire pressure, tire size, too many one wheel burn-outs, doing doughnuts, etc.) over long periods of time.

Pay a little now or a lot later, it's your call. Get a good shop to take care of you and don't make it a Firestone or Goodyear tire center. I usually fix what they break on their first attempts around here.

 

Well i am some what unhappy to hear that this has happened enough for you to be able to diganos with out seeing it heh, but i still cant fingure how to get the "cover" off.. it has bolts coming down into it from above a center support that i cant get to the top of on both the front and back sides of it. I really would rather repair this my self rather then take it to some shop where any 16 year old kid can tear into the car.

 

Drop the rear spring, take the two bolts out of the cross member mounts (you will have to pry the mounts lose as they may be stuck pretty hard). The front differential mount will support it and it will pivot down far enough so you can get the four bolts holding the cross member to the differential cover. Now you can remove the cover bolts and take a look at all the fun you are going to have :-)

 

As I said earlier, the 'cover' is not a cover, but a structural member of the entire assembly.
Pulling the entire differential out is the only way to be able to do any kind of repair. It's not going to be simply "Put the snap ring back on" and motor on.
Here's some steps:
1. Support the car off the ground with jack stands.
2. Remove the spare tire, lower cover and upper cover for room to work
3. Unbolt the driveshaft at the diff yoke.
4. Unbolt the 2 half-shafts at the side yokes
5. Unbolt the pinion support bolt under the diff front yoke
6. Unbolt the leaf spring at the trailing arms - BE VERY CAREFUL HERE
you could loose a finger. The spring will be under enormous tension
(a jack under the spring to unload the bolt will help)
7. Unbolt the 4 leaf spring bolts from the 'cover' and drop the leaf spring to the floor
8. Put a jack under the diff assembly
9. Unbolt the 2 diff support bracket to frame bolts and pry (and I mean pry) the support from the frame (it's likely rusted in place)
10. Lower the diff assembly to the ground
11. Now take off the 8 'cover' bolts to release the center carrier section from the cover and see what's broken inside.

If you are lucky, it may be that the snap ring popped off. After 100+ diffs I've done though, I've never seen this happen. It's usually the end button on the side yoke that has been ground down to nothing and there is no snap ring groove left.

Good luck.

 

If you are just removing the diff cover than this will help.:
You need to jack it up & place it on stands. Remove the wheels. Remove the strut rod holders from below the diff. Remove the shocks from the lower connection by the strut rods or the top end. Remove the leaf spring. (careful with that as you need to take one side of at a time with the use of a floor jack at the ends by the bolt. Place a vice grip on the spring so it will not slip off the jack when lowering the spring after you have disconeccted the long bolt at the end. The vice grip gives the jack pad a place to stop its sliding off). Remove the 4 bolts that hold the leaf spring under the differential cover . Place the jack under that also as its heavy as hell. Place a jack stand under the diff unit itself to support its weight. The face of the diff. cover has bolts that need to be removed . remove them as you can to start draing the lube. (Its thick & smelly. Your nostrills will retain that odor for some time ) The top cover bolts can be reached with a wrench if you reach in from the side over the brake assembly. The last part is the toughest there are 2 bolts that go into the top of the diff through the crossmember that have to come out. They are not accessable unless you either drill a hole or opening through the floor of your car right above the diff. or remove the crossmember(which is what I did, Its that long piece of metal that bolts into the body that runs across like the leaf spring above the diff.)) there is 1 bolt on each end that needs to come out. The fun part is removing the crossmember. I used a 6 foot steel bar to pry it loose from its spot & it took all of my strength . It will break loose and fall down. It probably weighs about 75 lbs. If you got all the bolts off the diff cover (which you should at this point) the diff plate it will come off with this crossmember attached Than you can access the bolts that hold it to the cover and its off. Place some heavy rags under it to soften the blow if it hits the floor. If you have access to a lift it will be much easier. I did it myself on the floor with a sears 3 ton floor jack & 4 jackstands. Power tools would have helped also. If I missed something I'm sure someone else will chime in. I did this about 7 tears ago and may need to do it again this week as I'm still having rear end problems.

If you are removing the entire rear diff assembly than you also need to remove the half shafts & the driveshaft. No need to remove the diff cover bolts but you need to remove the front diff suppor. Remove the entire diff along with the crossmember attached. Use the floor jack to lower it & guide it out. Make sure you have the car high enough to do this. Make sure its safe to go under and be real careful when breaking loose the crossmember as these things are pressed in from the weight of the car & if it wasn't removed in the last few years they will separate viciously when they finally break loose. don't stay under it.

You can look up info at http://vettenet.org/sharkrear.html and also http://w.w.w.bright.net/~corvette/howto3.html

good luck & stay safe.

 

Believe the others when they say that its time to rebuild the diff. Been there, have done that...

 

I feel your pain. I am doing a frame off on my 71, and today I took my rearend cover off so I could replace the yoke seals. Inside I found three chewed up broken bolts laying in the bottom. Looks like a trip to Bairs for me. Nothing is easy.

 

i just took the cover off my diff for the same reason yesterday, accept the yolk came out of the rear end due to a c clip comming off while removing the drive shafts...it took a while to get out but i eventually figured it out

i can take some pics that may be helpful, pm me if you want some pictures

Pat