'63 Differential carrier bracket

[Thomas B.]

In the process of disassembling and inspecting the bracket and bushings from under the car, I found that the diff and rear cross member have rotated so that the holes in the diff are too high to align with the holes in the carrier bracket.

Any suggestions on how to get things rotated back into place?

Thanks

[Duke W.]

Re: '63 Differential carrier bracket

IIRC the shop manual says to place a wood block between the body and axle nose to keep the nose from rotating up, but that doesn't always work. A pry bar (demolition bar, Wonderbar, etc.) can be used between the bracket and axle to pull the nose down to align the bolt holes. I forgot exactly how I oriented the bar, but you'll figure it out.

Duke

[Thomas B.]

Re: '63 Differential carrier bracket

Here's a pic of the extent of the hole misalignment on my car. Also included a pic from the internet of the diff mounted to a bare frame (not my car) for illustration purposes. Also included a link to a 2008 thread on the subject with some possible solutions.

I should mention that one of the front bolts on the carrier bracket was missing when I first started on this. The other front bolt was in place but the hole in the bracket has elongated over time due to forces on the carrier. Also, this bolt and the rear thru-bolt were not real loose but not as tight as they should have been.

I believe the weight from the rear crossmember and the fact that it doesn't align with the spring is what causes the uplift on the front of the diff. In my case the crossmember has rotated along with the diff since they are connected.

https://www.forums.ncrs.org/showthread.php?61190-c2-diffferential-mounting-problem

https://www.motortrend.com/how-to/1903-upgrading-the-front-differential-bracket-on-c2-1964-corvette/

Zip has a 63-64 bracket:

https://www.zip-corvette.com/63-64-differential-front-mount-bracket-reconditioned.html

[Timothy B.]

Re: '63 Differential carrier bracket

If the spring is still attached to the rear housing and trailing arms put the cars weight on the tires and I think you will find it easier to attach the front differential bracket.

[Duke W.]

Re: '63 Differential carrier bracket

,
I believe the weight from the rear crossmember and the fact that it doesn't align with the spring is what causes the uplift on the front of the diff. In my case the crossmember has rotated along with the diff since they are connected.

If the spring is connected, and the the car is on the ground or on jack stands or a frame hoist the spring force is trying to pull the axle cover down, which caused the nose of the axle to rotate up on the cross member axis due to the flexibility of the axle cross member mount bushings.

In the 2008 thread you referenced I offered the same advice as in this thread.

Duke

[Thomas B.]

Re: '63 Differential carrier bracket

I agree that with the car on the ground the spring is pushing up on the diff. So, if I put the car on jack stands and disconnect the spring from the trailing arms I may be able to rotate the diff forward with a pry bar. The cross member may still be offering resistance so maybe loosening the two end bolts may help by allowing it to rotate back forward with the diff.

I may even take this opportunity to replace the rear spring. A previous owner apparently replaced the stock 9 leaf spring with a 7 leaf spring and kept the stock front coils. I'd like to get it closer to the stock setup and hopefully soften up the ride a bit.

I'm assuming the 7 leaf spring on my car would be a higher rate spring than the original 9 leaf.

[Duke W.]

Re: '63 Differential carrier bracket

No, the spring force is pulling down on the axle cover, which causes the nose of the axle to rotate up about the axis formed by the axle cross member because the rubber cross member mounts are flexible.

You don't need to remove the spring or loosen the axle cross member. With the car on the ground a drive-on lift, on jack stands, or a frame lift, all you need to do is orient a demolition bar between the axle housing and front bracket in a way that you can pry the axle and front bracket slightly in order to line of the bolt holes.

It's a 10 second job to line up the holes and start the bolts.

Duke

[Thomas B.]

Re: '63 Differential carrier bracket

My thoughts. With wheels on the ground, the diff housing has to bear on the spring to transfer the vehicle weight to the spring. With wheels off the ground and on jack stands, most weight is off the spring but does the spring actually pull down on the diff housing in this scenario? If so, that’s great because this would tend to rotate the diff down about the axis of the rear cross member and help to align the holes in the diff with those in the carrier bracket.

Nov 20:
Got the holes to align and bolts installed. Disconnected the spring ends from the trailing arms and dropped the rear cross member down a bit. Was able to leave the exhaust in place and spring connected to the bottom of the diff. Now that the spring is disconnected I can install my new spring bushings.