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Old August 14th, 2019, 10:34
notamechanic notamechanic is offline
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Join Date: Mar 2016
Location: Orange County, CA
Posts: 119
Pinion shaft not clearing ring gear.

Originally Posted by TRCM View Post
Ok, to begin with, that's commonly called the center pin, not the pinion shaft.

And this is common with non-stock ratio gear sets, especially the higher ones (4.56, 4.88, 5.13, etc). I had to grind down a tooth about 0.040" on the ring gear to get the center pin in on another vehicle when I installed 4.56 gears.

What this shows is laziness on the part of the installer. Usually, you can rotate the ring gear so the space needed for the center pin is between gear teeth, but that requires checking for clearance which many don't do as it may require putting on and taking off the ring gear a few times. The fact that the center pin was ground for clearance confirms the lazy factor, as they decided to do that instead of doing it correctly.

If the center pin has been ground , it is weaker, even in a stock open diff, and that same pin cannot be used for a locking diff, as the pin diameter is a key part of how it all works.

Can you push the pin thru the other direction ?

If not, your only choice is to either remove the carrier and remove/reinstall the ring gear (which requires setting it up again), or grind that offending tooth down just enough to give you the clearance you need.

Thanks for clearing up my terminology. The locker instructions identified the center pin as the pinion shaft.

.040 seems very little, I think Id need to grind at least twice that to get my center pin out. Any idea what would be considered safe or unsafe amount to grind off? Im quite weary to do so since I spend so much on the regear.

The pin will not clear on the other side either. It actually meets between two of the ring gear teeth on one side, but still not nearly enough clearance to remove.

Will setting it back up be all that difficult? Since shim measurements are already set up. Also, i think Id have to grind the teeth down regardless. Will need to have the ability to remove it if I ever break a shaft.

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