GM 8.6 Differential w/G80

mllester325 · January 28, 2018

Hi everyone! I have a problem I haven't had to deal with before. Today I was replacing the rear axle bearings on a used 8.6 differential w/G80 that I am going to install in my 2000 Yukon XL. The left side worked just like it was supposed to. The right side did not. I removed the clip and the right shaft wouldn't come out by hand. I used my slide hammer it came out after 3 or 4 pops.I replaced the bearing and seals with no trouble. Tried to put the shaft back in and it gets close to seating, but stops about 1.5 " short. So I don't know if I let it rotate and now it is out of alignment or is there something up with this differential? I do not know its history.

I have seen internet posts with guys cautioning that's it is difficult to get axle shafts back in in things get out of alignment, but I have not found any guidance on how to get things back in alignment?

Does anyone have any suggestions?? Thanks In advance!!!

Mark

Doug_Scott · January 28, 2018

Generally the only gears that can move with the cross pin out are the two gears that the pin holds in place. The side gears cannot move out of place while the other two are in place. This will sound odd, but, are you sure you have not crossed the axles? Typically one axle is longer than the other.

Have you tried to lift the axle up by pulling down on the flange on the end of the axle to see if the axle is not centered in the axle tube? Also, can you put your finger into the side gear where the axle is supposed to go and feel any alignment issues?

The picture shows one axle fully inserted into the differential, but without the "c" clip installed. Is this the axle that is not appearing to be fully inserted? If it is, you have crossed the axles side to side.

mllester325 · January 28, 2018

Thanks Doug! The one that is inserted is the left side. It slides right in like it should. The axles are same length I believe. I did mark them when I removed them - but either shaft installs beautifully in left side and neither go in all the way on the right.

Doug_Scott · January 28, 2018

Grab a flashlight and take a look down the axle tube to see if something managed to get trapped in there. It may be as small as one of the rollers from the old axle bearing. If there is nothing there, and if you are 100% sure the correct new axle bearing was not packaged wrong, then you will have to remove the guts of the differential I do not know if the side gears and locker can be removed from the carrier with the carrier left in the housing.

Make sure that the axle bearing is correct though. If you can remove it without damaging it, I would pull it back out and see if it can slide onto the bearing part of both axles.

mllester325 · January 28, 2018

The axle tube looks perfectly clear. The old bearings came out easy and intact. in fact, I was surprised how easily the bearing came out on the "problem" side. I keep coming back to the trouble I had pulling out the axle shaft on this side the first time. This is the first time I have ever used the flange in my axle/bearing puller tool kit to remove an axle. Mine have always come out very easy? maybe I have just been lucky.

I really didn't want to have to take the carrier out, but am afraid that may be the next step.

I really appreciate your help. Thank you.

Doug_Scott · January 28, 2018

Double check the actual inner diameter of the new bearing first. It only needs to be .010" too small to stop the axle from going in. There is a small step down on the axle from the bearing and seal surface to the rest of the axle. If the bearing is defective/packaged wrong you won't see it by eye, but it would stop the axle from fitting. The bearing/seal surface is about that inch and a half you are coming up short. If you remove the seal, then try to insert the axle you will see if the axle stops right where the bearing surface starts.