I was going to change the pinion seal and I found out I had the wrong seal. So I took a break. While on my break the boy put the flange for the u-joint on the rear end with the impact. Now the rear end will not turn. What did he do?
He over tightened the pre-load for the bearings on the pinion. There is a "crush sleeve" in there that pre-loads the bearings, it will need to be replaced. If I remember correctly the drag should be 15 - 20 in.lbs. Need to check the repair manual for how to and how much.....
6-9 in lbs without the seal. I have a Ford service school book for servicing the 9". I always hated those crush sleeves. The factory procedure is to assemble the pinion without the seal and crush the sleeve until there is 6-9 in lbs of preload on the pinion bearings. Remove the yoke and install the seal...then reinstall the yoke. I find this procedure ridicules! The crush sleeve is to be used only once. Yet the service procedure is to use it twice and there is no pinion nut torque spec. Under heavy duty use, the factory installed shims. Even in a production environment (dealership), I shimmed every pinion. I have several 9" center sections setup with different options...Detroit Lockers, TractionLoc, and different rations...every one of them is shimmed. I use 1350 ujoints. If I swap a center section into some other vehicle, I can change the yoke without impacting the pinion bearing preload. Anything else is jeopardizing the setup.
I've skipped these steps and changed yokes and pinion seals for short term applications. But I would not do it for a long term solution.