Differential surging noise

Manns53 · May 3, 2017

Bought this truck about 6 months ago didn't have this noise, started noticing it the last 30 days or so. Just changed the U joints and axle bearings, had seals leaking a little and had just started hearing a Ujoint pop a little so no loss there but they didn't take care of this noise. It's a surging rubbing sound almost that increases with the speed of the vehicle until about 25 or 30 mph. Probably still a faint wine higher speeds but it blends in with road noise and you don't notice it as much. But it's pretty bad from 0-30 enough to hear it outside the truck. Didn't notice any excessive wear on the ring and pinion everything looked ok to me when had axles out. No play in the driveshaft or pinion bearing. I took the ebrake shoes off for awhile to rule those out, no change. But in trying to isolate the noise I got it up on jack stands and put it in gear, crawled under it, and the diff would make a clunk about every 5-10 seconds like the carrier was locking up for a second. Pretty loud pop. Never does this while driving. Didn't know if this was normal with no load on it? But while in the air it def sounds like the noise is coming from the differential. Why I figured the axle bearings would solve this but no luck.

Pinion gear or main bearings?

Doesnt look like diff has ever been changed or messed with but could be wrong.

newdude · May 3, 2017

The diff will lock with the truck in the air and the wheels rolling in Drive that is normal. The G80's flyweights are noticing the slip left to right and its locking the diff.

Does the noise sound louder at the nose of the diff (pinion side) or towards the rear of the diff? I wouldn't rule out a messed up pinion bearing. The races could be scored right up. Really, you almost won't know for sure unless you at least get the diff out to inspect the side bearings, and then the pinion bearings if the sides are good.

Manns53 · May 3, 2017

Thank you for your reply I just finished the axle bearings yesterday so figured I would try to find out some opinions before proceeding further. Guess I have to take it all back apart again to dig further. Have never set up a differential before am I able to disassemble and reassemble with checking or setting any clearances?

Or more important will I be able to change the pinion bearing and/or carrier bearings without having to set anything?

I figure no, that I'll have to get a new crush sleeve and do everything as I'm setting up the rearend diff for the first time. Just wanted to see if someone has had a similar noise and a solution before I proceed. I did find the rear caliper pins on the right side wasn't moving freely like they should and plan on taking care of this. But doubt that's my cause because the sound doesn't change when I brake other than slowing down with the speed of the truck. When turning right or left it doesn't change either.

If it doesn't hurt the diff to run off the ground and clunk like it was doing I can try to isolate the sound a little more.

tankdog03 · May 10, 2017

I got that sound from the front drivers side.. I believe it to be front differential needle bearing, I'm hoping it's that simple anyways.. both front seals are leaking, but I check the fluid regularly and haven't had to add any in the past few months, so it's a slow leak..

But that growling sound is very annoying.. it's not hub bearings because I've changed them twice since I bought it with moog.. thought it was a bad hub and changed them within 2 months.. noise went away a little, then I thought it was uneven tire wear, rotated tires, got a little quieter, but now the sound is back.. I do have wear on the insides of my tires.. I'm doubting it's my tires making the sound.. but I do need new tires soon.. they was balanced with the self balancing beads.. and they suck from 10mph to 45mph. Once on the highway at 70/75mph they balance out pretty good. But I will never run balance beads again that for sure.. I should have the beads removed and rebalanced but I don't think the tires are worth the balance and remount fee

Sent from my SM-N910T3 using Tapatalk

Manns53 · May 10, 2017

I have seen tires make a substantial noise so it could be. Or it could be in the front diff.

I'm just about to wrap up the rebuild on my rear differential. Just got all the preload set and checked my backlash. Just need to put axles back in it, diff cover and brakes and fluid and should be good to go. In my case it was pinion and main bearings wore I believe. They didn't have lateral movement but the front pinion race looked like it had some wear to it. I think the noise was coming from too much backlash due to the wear in the bearings. After removing the driveshaft it had more play in the backlash than it does now after changing the bearings. The front shim was a .033 and it was wore down and I could hang my fingernail on the lip. I replaced the shim with another .033.

The old one had wore down to about .031 1/2 to .032.

Add that in combination to the carrier bearings being wore it created too much backlash. Hopefully this cures my problem as I havnt competed it yet. Took the day off to smoke some ribs. Have to keep Priorities straight!