[Novice Goat]

Finally getting around to replacing the original rear end gears and installing a posi. Took the old one apart 6 months ago and am finally getting ready to final assembly of the new when I see the attached ring that I don’t remember where it goes. Seems like a carrier shim to get the backlash right, but want to get confirmation from someone that knows. I’m hoping it’s not part of the inner pinion race, because it took me forever to get the wear pattern right.

[johnta1]

That thick, I'd say it's a carrier shim.
Do you have 2 of them?

[steve25]

When you slip it on your old pinion does it slap around from being too big in ID?

If so then there’s your answer.

Like John posted, at least for a 8.2” rear it looks like a carrier spacer.

[PontiacHO]

Yes. Carrier shim. Cast iron shims were factory shims. Unfortunately they tend to shatter when tapped in.The factory assembly used some massive case spreading equipment.

[Novice Goat]

Thank you for the quick response. A carrier shim made the most sense to me but I wanted to make certain before I put everything back together. There was only one of them, so I guess from the factory they only used one shim, instead of the multiple varying thickness ones that come with the the aftermarket kits.

[TXSTARFIRE]

I think there should be two of those shims. Every differential I have done had one on each side.

[mgarblik]

There is always 2 of those cast iron shims used from the factory. Often 1 will be stuck against the side of the axle tube so look closely in there. As mentioned, when you try to install the shim, it will need to be tapped into place. They crack very easily. Make sure it is lined up as straight as possible and use a plastic shot filled hammer to GENTLY tap it back into place. If if goes in smoothly with little effort, the housing has relaxed over the decades and the bearing preload will have been lost. It should install pretty tight. Then re-shimming from scratch with a service spacer and multiple shims will be required. Also make sure the case bearing caps have been kept in order, right and left and top and bottom for correct assembly. This is important because the case is honed from the factory similar to engine main bearing caps and mixing all that stuff up often results in trouble and broken parts. Good luck with it.