65 Rear Differential Mounting-pinion seal replacement

[Grant M.]

Looking for advice re: the front carrier bracket for a 65 differential. My mechanic, despite having the 1963 service manual for guidance, failed to put a 1/2 inch piece of wood between the carrier and floor and proceeded to remove the nuts and washers from BOTH front through bolts and then tried to remove the rearmost bolt (the one you're supposed to only loosen). As predicted in the service manual, I think the carrier has twisted upward and now the rearmost bolt, which has been pulled out of the carrier bracket on one side and is protruding on the opposite side in contact with the jack well floor, can't be re-installed nor removed.

I'm wondering of the source of torsion which causes the carrier to twist upward is the transverse spring, installed to the trailing arms, and if so, whether disconnecting the spring from the trailing arms would allow the carrier to be returned to its position on the carrier bracket and the rearmost bolt to be re-installed (pushed through) the other side carrier bracket hole, prior to following the service manual instructions correctly (ie: merely loosening the rearmost bolt, removing the front bolt and rotating the carrier bracket downward to permit access to change the pinion seal).

Can anyone advise?

Thanks,

Grant

[Bob R.]

Re: 65 Rear Differential Mounting-pinion seal replacement

All of the tension is from the rear spring. If you are using a 4 post lift when you release the spring you will have to support weigh of the car.

[Grant M.]

Re: 65 Rear Differential Mounting-pinion seal replacement

Bob, by that do you mean the weight of the trailing arms/rotors/side yokes and shafts etc? The shop is using a two-post lift. I have swapped out two rear springs (65 and 78) using jack stands and don't recall any issues.

Thanks for replying.

Grant

[Bob R.]

Re: 65 Rear Differential Mounting-pinion seal replacement

The rear spring is supporting the weight of the rear of the car if you disconnect the spring the car will drop until the rear suspension bottoms out on the body of the car not a good thing. With a 4 post lift use a couple of jack stands under the rear of the frame to hold the rear of the car up. With a 2 post lift everything is just hanging so you can release the spring. You may have to manually hold the weight of the wheels up a bit to align the front carrier bracket. By the way the only way to remove the bolts from the front carrier bracket is to drop the entire rear end. Those long bolts will hit the fiberglass floor of the car tunnel and won't come out. The 63 and I think 64 rear will allow you to remove the forward bolts as they are short but not the rear bolts but newer cars used 2 long bolts. Many cars have holes cut in the fiberglass to allow the bolts to be removed.

[Grant M.]

Re: 65 Rear Differential Mounting-pinion seal replacement

Yes, I note that other threads on this subject and the Willcox Corvette instructions all note that the frame should be supported so that the wheels hang free (as was the case when I changed springs some years back. I guess I'll have to cut a hole in the jack compartment to get that front bolt out (the rear bolt is only supposed to be loosened. To go back to my original questions, once the spring is disconnected, should I be able to re-install the rear bolt through the carrier bracket?

Thanks again for your help.

Grant

[Frank D.]

Re: 65 Rear Differential Mounting-pinion seal replacement

The only source of tension on the differential case IMO, is the spring under pressure attached to the differential case via the perch with the 4 bolts through it. If you disconnect the spring at each end and it assumes its full arch I would think all the tension is then off of the differential case and the bracket could be rotated down. You would be only working against the pressure of the sombrero bushings as the rear crossmember is attached to the differential through 4 bolts at the top (red circle). That's what I think anyway.

[Duke W.]

Re: 65 Rear Differential Mounting-pinion seal replacement

It's not clear to me the current situation, but the bracket holes and carrier holes can be lined up by using a pry bar between the bracket and carrier to line them up.

Duke

[Frank D.]

Re: 65 Rear Differential Mounting-pinion seal replacement

It's not clear to me the current situation, but the bracket holes and carrier holes can be lined up by using a pry bar between the bracket and carrier to line them up.

Duke

And if that is what is required the OP should make his mechanic do the prying, no need for him to get a hernia for this screw-up.

[Grant M.]

Re: 65 Rear Differential Mounting-pinion seal replacement

Frank/Duke,

Thanks for this. With your advice, I think we'll be able to fix it. I'll definitely be after the mechanic to do the dirty work (under supervision this time). One more case of people 'learning' on a vintage Corvette! Been there before and maybe will be again...

Regards,

Grant