pinion flange replacement

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Oct 11, 2012
I'm replacing my pinion flanges on my 73 fj40 to the 4spd style and am having some issues. The front went on fine, torqued to 160 ft lbs and spins freely. I put the rear on, and torqued to 160 ft lbs, and have a really hard time turning the pinion by hand. What would cause this, and what is the proper way to fix?

I double checked its in ft lbs. I did a search, can't find why this would happen. I know there's different shims, but don't know why I should have to do that from just simply switching flanges?
if for some reason the front diff was assembled or set up with a spacer/shims you could torque the pinion nut and affect preload minimally, if it is a crush sleeve re-torquing the pinion nut could result in a significant increase in pinion preload.
When I removed my pinion nut the first time it wasn't really tight, and now I torque it to 160 ft lbs and have I hard time turning it. I think my pinion shims are shot, does this sound correct?
Should I back the nut off to get the proper preload or replace the shims inside?
Should I back the nut off to get the proper preload or replace the shims inside?

We ran into the same(ish) issue on the same day! I think you have to shim it until the torque and preload are within spec. It looks like the shims protect the bearings from taking the force of the 150 or so ft. lbs. applied to the pinion nut.

Check this:

I'll update it tomorrow when I'm back in the shop.
Sounds like the rear has a crush sleeve in it instead of spacer and shims (or there is damage to the shims). The most correct answer is to replace the crush sleeve once the pinion nut has been removed, but I think it is pretty common to reuse if you are not changing bearings and such. Like if you are changing just the pinion seal. A search on reusing crush sleeves may shed some light. It would also be prudent to pull the pinion flange back off and visually check to see if it is a crush sleeve or solid spacer, like referenced above a shim may be damaged and need to be replaced and rechecked instead. The spacer and shims should be under the front pinion bearing and you would add shims to reduce preload.
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Correct me if I am wrong, but don't you have to disassemble the entire third member in order to put these shims in place?
Update, Found the problem. Got home from work pulled the pinion flange back off, pulled the seal, bearing, one shim and washer. Looked inside with a flashlight and saw about 1/3 of a shim inside! Pulled it out with a pair of tweasers. Pulled the drain plug and found the other 2/3 of the shim in the form of flakes. Pulled the diff cover , everything appears good. How much damage do you think that shim did to the bearings when it disintegrated?
Thanks for the help, I'm gona order a shim kit. It might be a good time to think about installing a locker as well.

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