Cost me an entire rear end. Stupid design. Ruined the pumpkin. If anyone googles and finds this thread, some advice: Find a used open diff 9.25 rear end from like a little 3.7 single cab or something in a junkyard. They can be built up same as a factory LSD or aftermarket and it's guaranteed to not have that prior failure in it. Saves big $ when rebuilding.

 

Where area is the noise coming from? You have picture of inside with the cover off, like close up on the bearing caps?

 

Thanks Prismatic and fj5. I'm going to use a stethoscope and isolate the source of the grinding. I initially assumed wheel bearings, but I was wrong.
Prismatic, how did you inspect your diff? Did you take out the ring/carrier then inspect the carrier (side) bearings?
Thanks for the suggestion about a 3.7 rear. I can see advantage to building up a diff before installing on the truck. I think most difficult part of rebuilding diff while on truck/jack stands is going to be setting pinion pre-load. It was major effort getting 85 ft/lbs when re-attaching the prop shaft.
Fj5, I thought noise was coming from the wheel area, but it could be an echo. I don't think the bearing caps have ever been removed and am confident they are oriented correctly. Got no idea what is going on underneath the caps though, I should have checked when I had diff open last week. I get to do it all again.
Pinion turning torque was 8 in/lb when I checked prior to removing old pinion seal, and I set it to 10 in/lb on re-install. Do you think adding some pre-load is worth a shot?

 

I'd torque it all to factory specs. When do you hear the noise, only when driving? Or can you reproduce by spinning the yoke by hand?

 

You didn't accidentally bend the dust shield into the rotor did you?

 

Always possible, and I'll check. I'll rule out brake noises by removing calipers and rotors and turning drive shaft with truck on jack stands.

[QUOTE=fj5gtx;3559023]I'd torque it all to factory specs. When do you hear the noise, only when driving? Or can you reproduce by spinning the yoke by hand?
I wish I would have thought to spin yoke and check for crunchiness and noise. I thought problem was wheel bearings and pinion seal. I hear noise when driving and when in drive on jack stands.

Plan now is to put truck on jack stands and run in drive to try and isolate noise. I'll do a second run without rear wheels, brakes, or rotors to see if I still get grinding. If noise still present replace bearings, pinion, and ring gear. I'll post a video.

 

Oh jeez, make sure you've got it blocked up really well before you get under that thing! You won't be able to slow down the driveline with the brakes removed, so plan on just turning off the engine... slamming it into park won't be a pleasant experience.

 

Concur fj5, I wouldn't get under a running truck for any reason. I have a long tube that I'll hold up against the diff using a stick, and use it like a stethoscope. I'll also use an IR gun to look for hot spots after shut down.

 

This is the sound. I listened all around the diff with a stethoscope and everything sounded good.
I have about 1/16 play in the rear u-joint. My working theory now is that the u-joint is making the noise.
The pinion seal has been leaking for a while, but was not the cause of the noise.
I removed wheels, brakes, and rotors to eliminate any brake noise.
Take a listen, I'd appreciate hearing what you think.

 

I don't really hear anything untoward.... but then, my hearing sucks anyway.