Join Date: Jul 2006
Location: Northfield, Illinois
If I understand you correctly, here's what happened. You have simply disenguaged the pinion gear from the ring gear. When you rolled the car backwards, the pinion was pushed forward - out. no problem. When you rolled the car forward, it pulled the pinion in and jammed it into the ring gear, locking everything up. STOP now, do not apply any force, or you will damage the ring gear, or pinion or pinion bearings. To correct the problem, reinstall the pinion nut, and tighten (not all the way) firmly enough so as the car (on its wheels, not in the air) can be rocked, gently, backwards. Both rear wheels must be turning the same direction (backwards) at the same rate. With luck, you will hear a clunk as the pinion once again enguages with the ring gear. Then tighten the pinion nut further and check to see if it is now free.
I have been using the differential bottom as a jacking point for 45 years with a soft wood block. No problem. However, IF you had the old seal out when you washed the rear end, you have most likely introduced some moisture into the case. You should probably replace the gear oil at least twice after driving it until the diferential is hot, maybe 50 - 100 miles the first time, and then again at about 500 miles. The moisture usually cooks out and vents the half shaft breathers, but if not, it can eat up the bearings.
Look for a foamy or milky color to the otherwise clear yellow spirex as an indication of moisture. Be SURE to use the pinion flange holding fixture when re torquing the pinion nut. Incorrest preload (torque) on the pinion can cause all manner of nastiness. Gordon Raymond