Autopsy and 5.71 Motive Gears into Rob's front diff

Rob is the President of Northeast Toyota Crawlers, and when he pulled his front diff out to redo his front suspension, he found a broken ring gear tooth. Rob packaged up the diff in a 5 gallon bucket and shipped it over to us.

The entire diff at this point had zero preload on either the pinion or carrier bearings. You could freespin the whole assembly. Backlash was measured to be .014. The diff was then torn down. I had to use a puller to remove the pinion flange...

Upon inspection, the flange was no good, some funky stuff going on with the splines, making it impossible to get the flange on without pounding it, and the seal surface had fairly deep grooves in it. The first pic shows Rob's flange bolted to one of our spare flanges to transfer the second hole pattern.

The diff had a factory solid spacer, which will be reused...

The ring gear was removed, and bearings pressed off and on the carrier.

The new ring gear installed with Red Loctite and 75 ft/lbs.

Markings on the ring and pinion gears...

Put new races in the housing.

Time for reassembly. A pic of the jig to secure it, and Never-Sieze on the threads for the side bearing adjusters.

Initial pattern check was done with the original .081 pinion shim, resulting in this pattern:

Pattern was far too shallow, and also noticed the cause of the failure of the first gearset. With the 5.71 ring gear being so tall and the pinion so small, the edge of the tops of the ring gear teeth were just about rubbing the inside of the housing. This is the exact location of the broken tooth...

Hard to see in the pic, but there was actually a small spot on the housing that had been touching the ring gear and was worn shiny smooth...

So, had to do a little clearancing on the housing...

So after everything is all cleaned up, .012 shim is added to the pinion shim.

And the resulting pattern is spot on...

I'm sure this setup is going to be put to the test!