1989 D35 with factory Posi. Before the Turdy-Five bashing starts I'll let you know it will be soon replaced with a C8.25 with locker and chromoly shafts donated by a friend. But until then I'm driving it.

In any case, posi has worked great with both rears spinning pulling and getting me up an over some otherwise winching situations. However, if one tire leaves the ground then game-off. The tire in the air just spins. It seems both tires must have at least a little traction for the posi to lockup. My question is, is this normal?

 

No, that is not normal. If it is indeed a "posi" both tires have full power all the time no matter what. But more likely than not you have a limited slip, which will slip a little then divert power from the tire without traction to the one with traction. What you are describing indicates burned out clutches or other issues.

 

A 1 tire fire is perfectly normal even with a clutch type limited slip. Maybe this video will help a little.

 

Thanks for the info. This video is what made me think the factory posi was still working. Plus the other open-diff Jeeps didn't even come close to making it. Maybe it is worn-out and just borderline enough on this climb for me to think it was fully working.

 

Don't forget there r 2 separate factors.....axle torque and tire traction. The rollers completely eliminate tire traction and allow one to see how axle torque is, or isn't, applied to the road surface, via traction, by the 3 differential types....open, limited slip, locking. Lots of variables with a limited slip, a locker is either locked or not.