8.5 S Spring Posi

[Greg Reimer 7376]

On the late 70's-early 80's 10 bolt, there was a tendency for the axle retaining C locks to get wallowed out and a bit thin in use with the result of them falling out, then the tire,wheel,brake drum and axle would come out while the car was going down the road. Not a happy scenario.If you need that last little bit to get the spider gear post in,thin down the end of the axle a bit-not over .010" at a time, then try again. Be sure the C lock groove on the axle and the C locks fir snug-sometimes axles show that they are getting wallowed out from a bunch of loose motion between them. Make sure the C locks aren't worn thin or bent or they might be able to slip out as well. If the axles and the C locks are nice and snug, try thinning down the end of the axle a little at a time so as to maintain a minimal clearance there. You want axles that exhibit as little endplay as you can get to eliminate stuff getting looser with age and use and coming apart. This works on a 12 bolt as well,both rear ends are quite similar. Keep the spider gears snug in the differential carrier as well, too much looseness results in issues as well, but you don't want them so tight that lube has a difficult time getting in between parts that need it.

[dwydendorf]

The original posi units were made by Eaton. I think you can still get the original type clutches through a dealer that handles the Eaton parts.
The factory clutches were broken in on a break in machine after being soaked in a pan of gear lube. You could do something similar by assembling the differential with preload plates and springs and turning the axle a half dozen times in each direction. It won't apply as much pressure to the clutches as the breakin machine did but it would be better than what you have now.

[Randy Schonscheck]

Sorry been gone for a while. Got things working by doing the install with lots of gear lube and then rotating it about 30 to 40 tomes in each direction, It seems like it gives it alittle breakin mode to take the "fuzz" off. Everything fit perfect. Most experts on differentials do not like synthetic lubes either on limited slip posi 's. So I'm going to give that a try too. Been using synthetics for 30 years. Anyways, thanks guys for your help and advice. Randy