Rear end clunking

[Kruck88]

Searched through some other threads and didn't find anything that matches my symptoms.  It's an 05 Silverado 3500 DRW 4x4.  The only time I notice it is when going slow, as in walking speed, and either barely on the gas or at idle.  It sounds like a solid clunk with about every rotation of the tire.  I've jacked the truck up and ran it on jack stands, no noise.  I've turned the wheels by hand on jack stands, no noise.  I've removed the rear wheels to make sure there wasn't anything trapped.  Crawled under the truck and the u-joints seem fine, even greased them while I was under there.  

 

Next on the list is to pull the hubs to see if maybe something in the parking brake has failed?  Any more suggestions?  It isn't spring related as I know there have been lots of issues around that.  It doesn't seem to get better or worse when I turn.  There is no vibration or noise going down the hwy.  You can't really feel the clunk unless you are really really paying attention and the surface is smooth.  

[davester]

Maybe chock the front wheels and using the engine to spin the rear wheels.  If you know it has an open diff and not a G80, you might also chock one rear wheel and then other other and see if it happens on one particular side (If you have a G80, this is dangerous, as when the relative speed difference makes the G80 lock, then the chocked wheel will suddenly really want to spin).

[davester]

... and there's not much in the parking brakes to make a clunk, short of some part having come loose to roll around inside.

 

If you can't hear a loud clunk doing that test with the engine spinning the wheels, maybe try repeating it, and use a mechanics stethoscope (carefully) to listen to the backside of each hub, and to the diff housing, maybe you can hear something using it.

[David89GMC]

Did you clean the tires of all debris and check them for roundness? I often get what you describe and it's always a rock stuck in the tread, front or rear. Radial ply tires can fail with this symptom.

A clunk on each revolution indicates a wheel or axle related problem. The propeller shaft turns 4 times the speed of the wheels and final drive, so you can disregard that as a source.

Since this is a dually, I'd suspect the rear differential. After 16 years of towing and hauling it's not unusual for the rear end to go bad.

[Kruck88]

3 hours ago, davester said:

Maybe chock the front wheels and using the engine to spin the rear wheels.  If you know it has an open diff and not a G80, you might also chock one rear wheel and then other other and see if it happens on one particular side (If you have a G80, this is dangerous, as when the relative speed difference makes the G80 lock, then the chocked wheel will suddenly really want to spin).

I already tried that and couldn't replicate the sound.

[Kruck88]

1 hour ago, David89GMC said:

Did you clean the tires of all debris and check them for roundness? I often get what you describe and it's always a rock stuck in the tread, front or rear. Radial ply tires can fail with this symptom.

A clunk on each revolution indicates a wheel or axle related problem. The propeller shaft turns 4 times the speed of the wheels and final drive, so you can disregard that as a source.

Since this is a dually, I'd suspect the rear differential. After 16 years of towing and hauling it's not unusual for the rear end to go bad.

I have not checked for roundness but I would expect to feel something like that on the hwy.  I too am leery that it may be diff related.  What confuses me is that turning doesn't seem to change it and neither does throttle.  

[Kruck88]

I did some more investigating today trying to figure this out.  It seems to come and go so I drove the truck on the road a while came home and jacked the axle off the ground and ran the truck.  I didn't hear the noise but let it keep running.  When I hear the clunk on the road it sounds like it's in sync with the revolution of the tires.  While the truck was idleing in gear on the jack stands suddenly I heard it... a loud THUNK.  After another 5 seconds or so it did it again.  Sounded like it was coming from the transfer case.  I cycled the transfer case through it's ranges, ran the truck in reverse, back forward, and even up through the gears and never heard the noise come back.  One thing I did notice is that if I got on the brake pretty hard after running it up to about 50 mph on the jack stands the tires would stop, then a loud thump from under the truck.  I am assuming the T-case is chain driven so it sounded and felt almost like there was a lot of slop in that chain.  

[Mark Allen]

I spoke with my transmission rebuilder about this common issue. He explained that many GM/Chev truck customers describe a slight clunking noise that often occurs during acceleration from a stop or near complete stop. There is teflon grease that is coated on the splines of the driveshaft yoke that slips into the rear of the transmission. When the transmission fluid and filter are serviced, he recommends always removing the driveshaft with the yoke from the tail shaft of the transmission and re-coating the splines of the yoke with the teflon spline grease. He said GM doesn't offer this spline grease, but Ford offers it. He said that it is common for the teflon grease to dry out and dissipate over time and miles, causing a clunking noise that sounds as though it were coming from the rear differential. The teflon spline grease cushions the contact and connection between the driveshaft yoke splines and the transmission tailshaft splines.

[Mark Allen]

Motorcraft XG8A PTFE Driveshaft Slip Yoke Grease

[Black02Silverado]

This sounds like the same issue I had with my 2002 1500 Silverado.  GM fixed it with a new updated nickle plated slip yoke.  Took care of the clunk.  Seeing this is on a 3500 I would guess that it is a completely different yoke for sure, but might want to check and see if there was an updated one for yours as well.