Re: Rear Pinion Crush Spacer

Posted by DavidPackard on 2015/10/6 11:06:52
Concerning the pinion seal replacement procedure; I know the standard procedure is to pre-mark the clocking position of every component that is going to be removed, and upon seal renewal, reassemble with the goal of restoring the clocking positions, especially the nut to pinion shaft relationship. Apparently I have a long lost brother in Australia that has just introduced the idea of monitoring the axial play of the pinion and become fully awake when that axial play approaches zero. As with the standard procedure, Peter suggests a check of the torque required to rotate the pinion as a segregate for pinion bearing pre-load.
Now for the assumptions that I have made about automotive differential design. I see the crush collar as a rather unique spring that is intended to be plastically deformed during assembly, but that collar should have some amount of 'spring-back' when the load is removed. If the axial motion of the pinion is monitored during disassembly there should be some initial nut removal rotation that has no effect on the axial play of the pinion. After the collar spring-back has concluded a relationship between the nut rotation and axial play should be quite predicable by the pitch of the thread.
My '48 has a leaking pinion seal that may need replacement, however the leak is far less with the car being used regularly so I may not need to rush on that task. After reading this posting, my plan is now to use the standard procedure of marking the clocking position of everything in sight, measure the pinion torque prior to disassembly, and then try my hand at monitoring the spring back of the collar. Upon reassembly I suspect all of the stars should realign. I'll post my results if I have any new information to add to the collective experience.

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