steve walker

hi this is my 94 roadmaster 8.5 rear posi i can pull/push in out my axles 1/4 inch could the cluches be wornd down allowing for this slop??cclips wear down??pls throw in you thoughts thanks

svnt442

That seems rather excessive to me. I think if it moved in and out that much the C clips would fall off.
The movement of the axles shouldn't have an effect on the clutches as they are splined so the axles slide in and out of them.
My guess would be you have outer bearing issues if you have that much slop, but I could be wrong about that. There also could be an issue with the cross pin being worn down.
If there really is that much movement I would pull the cover and inspect the cross pin at the very least.

steve walker

but if the cluches wear down woudnt the cclips loosnd up i didnt see any wear on pinion shaft

J-(Chicago)

Ok. First things first. Is this an Auburn posi, a trac lock, or a Gov lock?
The c clip sits in a recess in the splined side gears.
If it's an auburn, your cones may be failing. If it's a trac lock, your clutch pack may need another shim behind the side gear.

If it's a gov lock, junk it.

svnt442

The clutches don't effect the side gears like that.

J-(Chicago)

I disagree.

If it's a trac loc, the clutches are packed: Side gear-clutch-steel shim-steel shim-clutch-steel shim-steel shim-clutch-steel shim-carrier.
I forget what the ball park measurement to shoot for on the Gm carriers is.

On the Ford 8.8's I think 0.640" total thickness on each side is a good starting point, but that doesn't help this situation at all.

I haven't rebuilt a GM trac loc in a long time, so it would be a trial and error if i had to.

J-(Chicago)

I found a box of GM clutches in the garage while I was thinking about it.
To the best of my intelligent guessing, A gm trac loc clutch pack would go:
side gear-clutch-shim-clutch-shim-clutch-shim-clutch-shim-special bald shim(.060" in this case) -carrier. Driver's side pack measured .576" and passenger side, .571"

monzaz

Ok...well first lets just forget about the clutches...This is a factory car and will have the Auburn 30 spline c-clip posi unit in it.

On these units the cones will wear into the posi case making the cones loose in the posi case causing all that excessive play and you could also have alot of wear on the spider because of this AGAIN causing MORE play. SO be careful as you cuold loose a c-clip and then you will be in some series S--T for sure depending on the speed your going

Now onto the clutches.

YES the same effect will occur on the clutches being worn. MOST of the time what happens on the clutch rear posi unit s that a clutch plate will shatter and fall or be chewed up in the clutch pack and that will cause the slop and excessive in out plat in the axle.

AS far as the c-clip NOT falling out...PURE LUCK and inertial spinning believe it or not will keep them in place and the fluid acts as kind of a suction glue effect...BUT the luck will run out and KABOOM!!! your gonna know it!

Normally the side gear pocket and the center large cross pin (pinion pin) keep the axle end play in check. In a posi the clutch pack has to be shimmed correctly for the spider gears and end play to stay in spec. 10 bolt 8.5 trac loc units have a .085-.100 shim so if you forget to install that... The spider gears will be flopping and the axle end play will be HUGE and the axle will fall out...lol.

So be careful with a 1/4" end play. NOTHING to take lightly. get in that rear and find out what the deal is. Jim

I have attached the posi YOU should have in the Buick. If it does not look like this someone has been in there and swapped it for something else.

J-(Chicago)

Good post.

Since it's an Auburn, it cannot be rebuilt, correct?

monzaz

No not exactly true. We can work on the units and bring back alot of life. We can machine the cones and re shim the spider gears back to spec and you can get some more life back again all depends on the use of the posi as to how long the mods we do will last.

Remember with performance posi units, whether it is clutch or cones ...THEY Are always wearing out with EVERY TURN THE CAR TAKES. It is very little each time BUT still it is happening. friction wears parts and all posi units EVEN THE TORSON unit has gear to gear will wear out sooner or later.

Enjoy the posi while it works and when it goes just rebuilt it or replace it. PArt of life and it makes the economy keep going. Right?

I know not funny but it is true.

Jim