Question for All, I want to rebuild my Posi unit in my 1973 L82. #s Matching Car. The Diff code is (AB W1 06 E 2) I Know that it is an Eaton Carrier Unit. What I don't know is what type Posi unit it is. The Differential is original and without the Carrier out of the vehicle yet , cover off, I can see the Posi unit has the large open windows in it. Most likely the original unit. I want to go with the Steel Clutch set up with possibly losing the springs as in Tom's Diff. set up. How do I determine which Posi Unit I have? I want to order the correct Steel set up for this Carrier. Any Help would be greatly appreciated. Thanks

 

First, and I say this not to be sarcastic, but you need to learn more about this before diving in.
All Corvette posi cases from 1965-79 were Eaton, 3 or 4 series. Dana was in 63 and 64 and again 80-82, they are not good. What you have, who knows. If you are 100% sure that the diff is original and never been out, ok , but many of these cars have been flipped and things changed. Also, the housing, named the carrier, may have a replacement posi in it if it had been worked on in its life. Could be an Eaton, Auburn, Yukon, and even an open case- I have found plenty of "original" diff's that had replacement parts in them.

So, it is best to get it out and opened up for a look. I just did that today with a 1971 diff.

Going with solid steels and tuned posi is good BUT you better know how to do it and do it right. Do it wrong and you will have an open diff or break the spiders. Tom's video is a good starting point, but there is a lot more to it. When it's all done- correctly, there is no lash, no endplay, no binding, no freewheeling and it is balanced. Polishing, tuning, and milling the posi takes me about 6 hours on average and I have done 100's of them. First timers should expect to spend more time. Finding someone that knows how to correctly do this is going to be interesting for sure. I have repaired the work of some tuned posi's done by owners and some shops, they were all wrong, but then, that's why I got them.

Good luck with it.

 

Thank you for the Insight on this rebuild. I believe that I am very capable of Polishing, Balancing and Tuning the Posi. I like a challenge. I just want to be sure my Posi case is rebuildable. So for starters I need to Know the Identifying characteristics of the Eaton vs. the Yukon and Auburn. If you could shed some light on that it would be very helpful. I should have the differential out tomorrow and possibly the Posi out also. If I send some Pics would that help in Identification?

 

Rookie question: Why spend all that time removing the diff.?
Rebuild it on the car on jack stands.
GTR1999 does it the professional way since customers ship their units to him. Drill a hole in the cargo floor to access bolts if need be.

GTR...correct me if I;m goofy about this

 

Yeah, ....that is not the way to do them, they are not like a conventional solid diff that can be done in the car or truck. The cover holds the diff in the car, yes you can block it up, but there is no room to rebuild it in the car. It will only lead to frustration and/or injury.
Remove from the car, mount it on a stand and then you can work on it safely.

 

If you want to be 100% sure your posi case is rebuildable, you will need to fully disassemble it, clean it and do a magnetic particle or fluorescent penetrant inspection to determine if it is cracked. Very, very common to find them cracked in the corners of the “window”, less so in the cross shaft holes, so be prepared.

 

As mentioned, the posi cases do crack. There were several revisions along the way, but all can crack. If a posi is cracked it should be replaced.

Tuning a posi is not impossible to do, tuning a posi correctly, based on a video, one time attempt, and procedure, not as easy as expected. As I say many times about posi tuning, do it right it is the best operating posi out there, do it wrong and it will not work as a posi or it will break parts- like the spiders or case.

I am not trying to dissuade you from attempting but I no longer go into long, detailed, instructions online on how to do custom work. This is my business, and I do not intend to train my competitors in how to do custom work anymore. Look at the rebuilders out there, how many offer polished and tuned posi's, and if any do, are they right???

When Tom died, he took with him more information than most will ever know. When I hang it up in another 5-7 years, I may write that book I speak of but until then I will continue to build them.

Good luck, take your time, understand what you are going to do.

 

thank u Gary for all your knowledge and expertise.. you are definitely a dying breed in these industry and have helped soooo many people including myself . You will surely be missed when you retire.

 

First off you are fortunate GTR chimed in so quick for you. He doesn't advertise best on the planet for nothing and he ain't lying and a very nice and humble dude to boot. I brought mine to him along with many other parts. I doing my own car but know when to outsource. I drove all my parts to Gary and then back again to pick them up. A bit of a lead time but worth it. Folks ship diffs to him from around the world....literally. Fine if you wanna do your own..but question anything he says at your peril...well beyond my knowledge and am thrilled to get in with him before he punches out for good...which I hope is never....Good luck with your project. And no I do not get a commission for this endorsement...or do I Gary?

 

Thank you Keith.
As for this thread, I think I will back away from commenting anymore.
Good luck.