Eaton Posi rebuild - Chevelle Tech
Transmission & Driveline Transmissions and Differentials

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post #1 of 26 (permalink) Old Sep 2nd, 12, 10:49 AM Thread Starter
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Freddie
 
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Eaton Posi rebuild


This needs to be a sticky.

This is the guy that tought me how to build the Eaton Posi back in the '80s. This should be helpfull to many people.

This also works on the 8.5 Traction Lock, 9 inch, 8.8 and 7.5 Ford Trac Lock and sevral other differentials that use flat clutches. I go ahead and install the preload springs. Tom doesn't use preload springs. This is a choice that you will have to make on your own.
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post #2 of 26 (permalink) Old Sep 2nd, 12, 12:44 PM
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Re: Eaton Posi rebuild

Quote:
Originally Posted by big gear head View Post

This needs to be a sticky.
Done

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post #3 of 26 (permalink) Old Sep 2nd, 12, 12:44 PM
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Re: Eaton Posi rebuild

Thanks for this post, I thought this was a lot more difficult, Toms instruction takes away all the mystery. You said preload springs were a personal choice could you elaborate on the pro-cons? I'm having some issues with my unit and this exerscise is in the near future.

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post #4 of 26 (permalink) Old Sep 2nd, 12, 1:12 PM
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Re: Eaton Posi rebuild

Thanks for the post. Great information.
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post #5 of 26 (permalink) Old Sep 2nd, 12, 3:19 PM Thread Starter
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Freddie
 
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Re: Eaton Posi rebuild

The preload springs kind of help get the lock up started. As long as the clutches are tight then the springs are not needed much. Eaton has 200, 400 and 800 pound springs for different applictaions. The springs apply constant pressure on the clutches, so they will wear more when used on the street. If you do a lot of water burnouts then the 800 pound springs can help keep both wheels spinning while doing the burnout. I see a lot of cars with a posi, trac lock or other limited slip differentials that will start out spinning both wheels in the water and then one wheel will slow down and stop spinning. The heavier springs can help keep this from happening. If a car is used for drag racing then the clutches will need regular maintanance just like the valve springs, rod bearings and other parts.
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post #6 of 26 (permalink) Old Sep 2nd, 12, 4:44 PM
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Re: Eaton Posi rebuild

Hi Freddie.
Do you think you can get another segment added showing how to do the springs? That would be GREAT.

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post #7 of 26 (permalink) Old Sep 2nd, 12, 7:29 PM Thread Starter
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Freddie
 
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Re: Eaton Posi rebuild

I'll see if I can do something myself. I doubt that Tom would do it because he doesn't use springs. It's pretty easy to install the 200 and 400 pound springs, but the 800 pound springs are a pain. My memory isn't very good, so I might forget to do this.
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post #8 of 26 (permalink) Old Sep 2nd, 12, 7:38 PM
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Re: Eaton Posi rebuild

That would be great. Would you like a reminder ;-)

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post #9 of 26 (permalink) Old Sep 2nd, 12, 10:22 PM
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Re: Eaton Posi rebuild

>>> "My memory isn't very good, so I might forget to do this."

Transalation: bug me mercilessly till I do it.

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post #10 of 26 (permalink) Old Sep 3rd, 12, 12:49 AM
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Re: Eaton Posi rebuild

Quote:
Originally Posted by Tom Mobley View Post
>>> "My memory isn't very good, so I might forget to do this."

Transalation: bug me mercilessly till I do it.
No that is our wives job
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post #11 of 26 (permalink) Old Oct 17th, 12, 9:30 PM
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Daniel
 
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Re: Eaton Posi rebuild

Thanks for this video, I just had an issue with a posi unit and this video answered my question!

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post #12 of 26 (permalink) Old May 10th, 13, 6:38 PM
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Re: Eaton Posi rebuild

Great videos!

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post #13 of 26 (permalink) Old May 10th, 13, 8:50 PM
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Re: Eaton Posi rebuild

If you want a really tight setup you can set the clutches at 0 as long as you use the GM differential lube. This is how I set mine up and the only clicking I get is when I back my car out of my garage (It's at a steep angle and I'm turning at the same time).

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post #14 of 26 (permalink) Old May 21st, 13, 10:12 PM
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Re: Eaton Posi rebuild

Set mine up as tight as i could get then put in 400lb springs.works like a champ!works like it should.
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post #15 of 26 (permalink) Old Sep 17th, 14, 3:36 PM
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Rob
 
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Re: Eaton Posi rebuild

I just posted links to Tom's tutorials on Aug 27th in my build thread because I happen to be rebuilding my posi carrier a few weeks ago.

There is more than one way to secure the axel. Having the axel in the vise vertically would not work without a customized axel so I laid the entire assembly out on my bench then locked the axel into my vise using the pipe vise on the lower part of the vise. This allowed me to adjust the preload by using different thickness shims then spinning the carrier to check for proper preload. I ended up using a .040" and .0425" thickness shims. Picture in the link following link.

I kept the ring gear attached for this part so I had more leverage to spin it as I had no ring gear wrench like Tom was using. You must remove the ring gear in order to install the spring pack. There is no room for the C-clamp otherwise.

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Quote:
Originally Posted by LevonH View Post
Hi Freddie.
Do you think you can get another segment added showing how to do the springs? That would be GREAT.
I have a post showing how to install the spring pack into the carrier using a big C-clamp and some 1" wide steel bar stock. In my case I'm using stainless bar stock and a piece of hardwood to hold down the inside part of the spring pack while being compressed.

The little bolts you see in the picture are mandatory to hold the outside part of the compression plates together, it also keeps things from flying apart. I'm installing the yellow springs here but you can't see the yellow paint because it's only on one side of the springs.

First you tighten down the C-clamp about in the middle and put the small bolts into the outside holes of the spring plates. Once the bolts are in you need a couple pieces of 1/8" thick steel bar stock because you can't get a clamp far enough to the inside of the plate in order to make it fit into the carrier. The bar stock allows you to apply leverage to the inside part of the spring pack so that it can be inserted into the carrier. The picture is worth a thousand words.
65 Chevelle 2dr. post car build thread AKA The Chevelle from hell.

In case anyone is interested. Tom is now working in the retail end of the business. I found this out by calling Tom's old listed phone number. A nice lady answered the phone but it's now a new business for selling differential parts. Very nice to deal with and overnight delivery in Cali. Use the link below for the new thegearshop business. This place actually sells single differential parts without having to purchase entire kits. They had one of Tom's hardened spider gear shafts which I purchased because mine was worn pretty badly, it's no wonder Tom has a hardened version.
http://www.thegearshop.net/store/cart.php

This is the best link I could find for setting pinion depth and backlash.
http://www.hotrod.com/techarticles/d...install_guide/

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My build thread> http://www.chevelles.com/forums/56-pro-touring/613546-65-chevelle-2dr-post-car-build-thread-aka-chevelle-hell.html

Last edited by 65chevelle300post; Sep 17th, 14 at 4:39 PM.
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