Just rebuilt the 12 bolt posi for my '69. I have .055 axle endplay on both sides. Is this a big concern?


Thanks!

Sounds about right to me but, what do I know :D

.055" on a fresh rebuild is a lot of endplay. Should be more like .005-.010".
I rebuilt mine this spring using Alloy axles with the thick c-clip button, and ground them to fit. Finished up with .003" clearance.

I wouldn't be concerned. Many years ago when I first got my '65 (12 bolt posi) I noticed what seemed like a lot of axle endplay on both sides when I rotated tires first time. Since the car only had less than 10,000 miles on it by a middle-aged professional truck driver, I figured it must have been that way from the factory. This has been discussed here before several times.

Ya, I searched for 2 days on the internet and this site. Came up with answers from .022 to .125 as normal. It would seem to me that .003 is a little tight. After the the whole deal heats up I would think gauling would begin.

So apparently .055 endplay is middle of the road in my research.

Anyone else wanna chime in on this?

Did you replace the clutches and shim the preload? If you didn't then that is where you are getting the axle end play. If the clutches are set up right then you will have .005 to .010 in most cases. As the clutches wear the axle end play will increase.

Sorry I had to bring this back up again... saw that there really does not seem to be a GOOD answer for this question???

I build differentials for a living and have parts from my manufactures that are all over the place.
A standard axle c-clip is .150 thick
the c-clip button end slot will range from .155-.185 ish

Now with those numbers you already have a .005 end play with the slot alone.

lets say you have .040 end play you would have about .110 about 2/3rds of the c-clip holding the axle in with NO pressure applied.

NOW... Lets say you have a posi. the clutch pack has an ocrdinan effect when you launch hard and applies pressure to the pack which in turn decreases the end play YES more again ALL depending on how well your posi was shimmed from the factory / performance manufacture. which could be from .010 -.040

With all this factored in you could have ONLY LESS THEN 1/2 your c-clip holding an axle in its side gear before the c-clip falls out. A good curb bump on acceleration or a hard launch with tire shake at the track could be the demise of the axle being held in.

My recommendations are to get as little end play as possible with all the rest of your parts(clutch shimming and spider gear backlash) correct on their own specs. Try for .005-.020 I am sure you could run .030-.040 but that should be MAXIMUM.

remember that shimming the side gears can be done to lesson the end play BUT BE CAREFUL NOT TO BIND THE SPIDER GEAR BACKLASH AS YOU WILL BURN THEM UP TOO...

I hope this info helps some of you with the c-clip rears and confidence when installing your axle shafts.

Take care, Jim