I rebuilt and installed a '97 D60 in the front of my '96 f250. Nothing crazy, new bearings, reused the 4.10s and open carrier that it came with. I chewed up the shims a little during disassembly, so I used new shims with the same overall pack thickness. Pinion torque was in spec, backlash is right at 0.007" (spec 0.004-0.009"). Gear pattern looked good (or so I thought). It all started out swell, had some low speed 4x4 on dirt roads and there was no issue. A few weeks later, I was cruising about 30 in a few inches of unplowed snow on pavement and the axle started growling at me. The moment between loads from accel to coast was quiet, but either compression braking or accelerating had roughly the same effect. A low pitched growl that got louder with speed (only in 4x4). I slowed down some until I got off the mountain and took it out of 4x asap.

I felt the pumpkin when I unlocked the hubs. and it was warmer than I thought it ought to be. Since then, I've only had the front engaged a few times, and less than 10MPH when needed.

I got it back apart last night. Drained the fluid and there were no egregious chunks, just some small gold colored flakes, <1mm in size. I rechecked backlash. Still ~0.007". Rechecked the pattern, and It hadn't changed, and there was no gear chipping or weird wear marks.

What I did notice is that the inside ends of the axle shafts are really close to the side gear cross pin, and there was heat discoloration of the tapered end and inside end of the axle shaft splines. I'm not sure if this is normal or not, but they don't appear to contact the cross pin.

I've done all the reading online. Dana Spicer, Billavista, Ford, etc. on gear setup and felt like I actually did a decent job. I mean it was a simple rebuild. I'm at a loss for what's up, and am hoping someone will shoot some wisdom my way.

Discoloration:


Backlash:


Axle to crosspin clearance:

 

What I'm really looking for is someone to tell me what's wrong with the pattern. I thought it was okay, but if anything, the contact is too high on the tooth. I've seen conflicting info on the cause. Some diagrams say the pinion is too shallow, Billavista says it's too deep.

Pattern 1, drive side:


Pattern 2, drive side:


Coast side:



Since I have to tear it all back out, I'm installing an OX locker so I'll be back to the drawing board on setup anyways. I'm just trying to get a handle on where I went wrong so I can correct it next time. Thanks for looking!

 

Move the wear pattern closer to the center of the ring gear. You will have to shim the carrier and the pinion.