Team Chevelle banner
  • Hey everyone! Enter your ride HERE to be a part JULY's Ride of the Month Challenge!
1 - 13 of 13 Posts

·
Registered
Joined
·
14,987 Posts
Discussion Starter · #1 ·
Watching some you tube videos and the video posted by big gear heads sticky. On a Eaton posi is it as easy as knocking out the preload springs, swap out the clutches and spring pack and putting it back together?
The toms video in the sticky says its a posi but they only shim it without springs. I guess im wondering what im missing? This would be a regular factory three series eaton posi out of a 67 chevelle. Thanks. Jim
 

·
Registered
Joined
·
9,759 Posts
The springs don't really do much after power is applied. Most of the pressure on the clutches comes from the teeth on the pinion and axle gears pressing against each other. Because of the angle of the teeth the gears will try to push away from each other, which puts a lot of pressure on the clutch plates. This is why Tom leaves the springs out when he does a rebuild. The most important thing is to get the shims correct.
 

·
Registered
Joined
·
14,987 Posts
Discussion Starter · #3 ·
Do the shims come in the clutch kits? Or am I better off letting a shop rebuild the posi? Jim
 

·
Registered
Joined
·
5,069 Posts
I rebuilt mine with the above kit and watched Tom's videos.

I must have either done something wrong or maybe the case has too much wear. After putting it back together I get a jerking/popping going around bends and sometimes in reverse. At the track yesterday it felt like sometimes one tire would catch before the other.

I've changed the fluid several times and tried it with and without additive.

With the cover off if I moved a wheel forward and backward it kinda looks like the spider gears had some play, not sure if that's normal or not.
 

·
Registered
Joined
·
2,478 Posts
It's much more difficult to set up these posi's up per Tom's instruction than you can imagine. It's the opposite of easy, once you know how it's not too bad but until then even good luck won't help you.

You will notice that it becomes more and more difficult to install those spider gears as you shim it up. When you get it close with the shims you will notice that you need to have everything lined up precisely in order to get the washers for the spider gears installed. They sell thinner C-clips so you can dial in the axel clearance.

If you aren't biting into the C-clips then you aren't close enough with the shims. .005-.007 axel clearance means just that and you are better off doing this with the entire diff assembled out of the case laying flat on top of a bench.
 

·
Registered
Joined
·
2,478 Posts
I have a cut off axle that I put in a vice to hold the unit while I rebuild it. You will have to be able to turn the gears inside the unit while you are building it. You can put a wheel flat on the floor and bolt one of your axles to it and use that.
The cut off axel in the vise is a good idea.

I actually have a pipe vise on my bench vise that I use to hold one of the axels so I can lay out the entire assembly flat on my bench.

I remove the ring gear when I set these up. The differential with the ring gear removed can easily spin on the bench, just slides on the wood.

You can easily set up the end play for both axels while it's laying there on the bench, can't do that while it's vertical in a vise with a cut off axel. :)

Breaking in those clutch packs can be a pain either way.
 

·
Registered
Joined
·
5,069 Posts
I shimmed it real tight and it was a pain in the butt to get the gears and washers and what not lined up.

I also used the cut off axle in a vice trick for all this.

Before the rebuild I did have a lot of axle play, enough that it would knock the pads back on my disc brakes after a right hand turn so I had to pump the brakes to get them working again. After the rebuild that is no longer an issue.

It definitely spins both wheels on the street.

On the fence about taking it apart and trying again or just replacing the unit and trying to sell mine to recoup some of the costs.
 

·
Registered
Joined
·
14,987 Posts
Discussion Starter · #11 ·
So maybe a better idea is to buy a ring pinion posi and I stall kit (550 off ebay) and just start with everything new? Jim
 

·
Registered
Joined
·
5,069 Posts
Kevin, you might be better off with a Eaton Truetrac. Seems like you are doing some auto cross or road racing ans the Truetrac would probably work better for that.

Jim, the old Eaton is a good differential and if everything else is in good condition then it's worth rebuilding.
I've considered that route too.

My Eaton lasted a long time and suffered a lot of abuse, the rebuild kit was only $100 shipped or so, thought I was going to be saving money just putting in the new clutches and shims and letting her eat for another 8 years. Guess not lol.
 
1 - 13 of 13 Posts
Top