8-1/4 pinion depth shims

[4spdcuda66]

I'm doing a gear swap on an 8-1/4 rear end out of a '75 dart. This is going in my '66 Barracuda. The original gear was a 2.45, and I'm changing the carrier and swapping in a 3.55. The pinion depth shim that came out of the case is .071" thick. The shim was between the large pinion bearing race and the case. The shims I got from Dr. Diff. go between the pinion bearing and pinion gear. I emailed Dr. Diff about getting shims that go in the case, but got no reply. I guess customer service isn't their thing. I tried Randy's, but they don't have them. Does anyone here know where I can get the shims I'm after?

 

[Garrett Ellison]

The earlier 8-1/4s used them between the case and the outer race but sometime around 1976 (IIRC), the 8-1/4 shims went between the pinion and inner bearing race. I've heard of mixed reviews of swapping to carrier break in the 8-1/4's due to the difference in pinion location. But the preferred way of setting the the pinion is the smaller shims for the pinion to bearing and using an old bearing honed out just enough to to slide on and off of the pinion for measuring the setup. The new bearing is pressed on with the correct shims once you determine proper shim setting. Both styles serve the same function but arrive to the endpoint differently, either by moving the entire bearing assembly in the case or moving the pinion in the bearings.

 

[townsend]

The 1975 TSB states the position and part number of the shim changes sometime in 1975.
It says either type could be found that year.
By 1976 they all were changed to the newer style.
The earlier shims part numbers were 2931960 - 2931978. Thickness of each shim can be found in 1974 Chrysler parts catalog.
Sometime in 1975 the newer shim was introduced part numbers 3723620 - 3723637.
Don't believe the earlier shims are made any longer but most can still be found on eBay.

 

[4spdcuda66]

Thank you both for clearing the air on that. I guess I'll hog out another bearing for set up and see what the shims tell me.