Stuck posi clutches

[Lynn]

Sherri and I worked on the 69 Z for a good 10 hours today.

First time on the road. Drove 25 miles (open headers - maybe I am just getting old, but too loud for me!!!) to my brother's shop so I could mount new tires, and can do exhaust work tomorrow, as well as some fine tuning on the engine.

Posi unit was rebuilt with all new clutches. Bought it maybe 10 years ago, so it sat for awhile, but always in climate control, and it had zero rust anywhere. In hindsight, I probably should have disassembeled before installing it.

Used GM posi additive for first fill after going through the rest of the rear.

I am guessing that once the cluthes release the first time, they will start to break in and get better.

Right now, problem is they are stuck. No differential movement around corners. So far, I have only driven on OLD dry rotted tires, so maybe with new rubber they will break loose around the first corner. If they don't, anyone have any tricks for getting them freed up the first time?

[TDW]

On my Ford 3/4 ton, 4x4 Van, the clutchs locked up from non-use. I changed the gear lube to synthetic, then took it to a big parking lot and did figure eights. They slowly worked themselves free. Never had that problem again.

[hiperf69]

Just like what Tony said;
Lynn, you can cure this with a trip to "Wallmart".
If you go late at night and find an open area with the space,
Then crank the wheel hard to one side, slowly
Do 3 or 4 full turns and then the same the other direction, it
Will get the gear lube worked into the clutch.
After doing rearend rebuilds for 30 years I have seen this manny times,also
I am not a fan of Syntheic's but that is up to you, just make sure you get the "GM"
posi additive.
It is a "Must" have!!
I have never found an aftermarket that work even close.
Just my thoughts,Joe.

[Lynn]

That was exactly my plan unless I got another suggestion.
I think it will help once I get some real rubber in the back.
Eric is sending me some Hoosier Quicktime rear tires. That ought to do it.
Just mounted some original type Firstones yesterday, but not sure that thosee E70's will be enough.

Thanks.

[67rs/ss]

I had the same problem but mine only cleared up a little doing the fig 8's. Somewhere I read
to add another small bottle of the GM posi additive and to do the fig 8's in reverse. I am
glad to say all rearend noise is gone.

Tony

[Lynn]

I tried the figure 8's with my bias ply 70 series Firestones. No go.

Lots of burning rubber smell when I got back to the house.

I have some 275 60 15 Hoosier Quicktimes, but after test fitting, they are just too darn close to the lip to do fig 8's.

May have to wait to put some bigger rear tires on the back.

[x Baldwin Motion]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 67rs/ss</div><div class="ubbcode-body">I had the same problem but mine only cleared up a little doing the fig 8's. Somewhere I read
to add another small bottle of the GM posi additive and to do the fig 8's in reverse. I am
glad to say all rearend noise is gone.

Tony </div></div>


I'll second the figure 8's IN REVERSE to free up the rear.

[Lynn]

Taking the driveshaft out tonight and dropping it off to have it re-tubed tomorrow.

Will put one more bottle of posi lube in there and try the f8s backwards after I re-install the driveshaft.

Sherri got to take it for a spin this evening. Her first time behind an old muscle car (her daily driver is a M Roadster, so it isn't like she hasn't experienced performance).

[Lynn]

Put some modern radials on and did the fig 8's and lots of circles both left and right.
No go.
Took the carrier out last night &amp; removed the spring pack. Couldn't get the side gears to move on the bench. Was getting late, so I sprayed penetrating oil on the clutches from every angle and put it back together without the springs pack. More grease and another bottle of GM posi additive.

Was 11 by then, so didn't take the time to go do figure 8's. Drove home the 30 miles and the clutches are still stuck. Hmmm... I am starting to think the buy that &quot;blue printed&quot; this rear maybe got things a little too tight. Didn't measure clearances on the side bearings and spider gears, but suspect that may be my issue.

Not much time to work on it this week, so may have to wait a week on this. Sure cuts down on the driving enjoyment. Here I have this killer Z that runs very well, and it feels and sounds likecrap going around a corner. When pulling out of the gate, I normally just punch it so at least all I am getting is tire spin.

[Lynn]

Anyone have a part number for the spring plates? One of mine needs to be replaced.