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A while ago, I replaced the pinion seal on the 9" diff on a 69 Mustang. At that time, I made little punch marks on the nut and flange before disassembling, and turned the nut back to that point when I re-assembled. However, that position seemed to be too loose, as the instructions on this page:
says to torque it to 175 lbf-ft and check the pre-load torque along the way, not exceeding 21 lbf-in. This may be invalid, but I'm checking the pre-load by turning the pinon through the back lash, and long before I get to 175 lbf-ft, the pre-load exceeds the 21 lbf-in. Should I pull the pinion out of the pumpkin by the retainer to check this on the bench? If I had indeed passed the 21 lbf-in pre-load, should I replace the crush collar and start over? I was hoping to avoid that. On the other hand, it's probably the original one, and probably has seen some hard use, if the rest of the car is any indication.
Yes, I re-used everything since I was just replacing the pinion seal. As I said, I tried to torque the nut back to its original position, hoping it would just hold its original torque and loading. This has worked before on other 9" (and 8.8") diffs, but this one had an unknown past, and I noticed that I did not have to apply very much torque when I removed the nut, or when I put it back to where it was. I figured it must have been too loose to begin with, so I tried tightening it to recommended spec. But as I said, even before getting close to the approximately 175 lbf-ft spec, the pre-load torque went way past the 21 lbf-in spec for a pinion with a new seal.
Should I take the pinion bearings apart and replace the collar?
Also, I will re-use the shim to maintain the pinion depth, hoping that will retain the original setup. How important is it to maintain the same teeth-mesh between the pinon and ring gears?
If you are going to take it out I'd just go ahead and call Randy's R&P and get the crush collar elimination kit and be done with that piece of crap crush collar set up, I never use them in any 9" I build.