Rear driveline noise ?

[osufans]

I have just developed a driveline noise. It is rhythmic with the speed of the vehicle, not the engine, and it sounds like it is coming from under the backseat area, or even from the middle of the Jeep.

It is not persistent, and will go away on its own. I have yet to determine if doing anything specific causes it...it just seems to come on its own for no reason. It starts off like a scraping noise, then gets louder, turning into a thumping noise, then slowly goes away. I didn't see anything under the vehicle that could be causing it.

I am wondering if it's U-joint related, or something in the output of the transmission/transfer case? Or even possibly in the rear diff.

It doesn't appear to be transmission related, and I only say that because the ****** will shift between gears (kick-down and up-shift) while the noise occurs, and has no effect on the sound of the noise.

Any ideas where to begin looking? I'm going to check the rear diff and U-joints first. I have diff fluid and it needs changed anyway.

Thanks for the help!

 

[DirtyKK]

Sounds like it could be a u-joint and the easiest place to start troubleshooting. Does it make the noise while accelerating and maintaining speed, then go away when you let off the gas? Other things I would check, or just go ahead and change is your tcase and diff fluids.

 

[osufans]

Front diff, transmission, and T-case fluids were all done within the last 5-10K miles. I haven't done the rear diff yet, just never got around to it. Guess I will be now.

As far as load or no load, doesn't make a difference. To be honest, it sounds like a brake when something starts dragging and the rotors are kind of out-of-round...that pulsing/scraping noise that they make....but this also starts thumping.....and it comes and goes on its own. Also, pressing the brakes also has no effect on the noise.

 

[tommudd]

Check the rear u joints, drive down the road a ways then come back and put your hand close to it, if its bad it will be HOT! They rust up and go solid!

 

[osufans]

thanks tom....do these things have a rear slip-yoke? do those ever bind? just thinking of things to look for.

 

[DirtyKK]

Now that you mention brakes I had a caliper sticking and and would cause somewhat similar issues. I could tell it was the caliper or at least something with the brakes because when I stopped to investigate the issue one rim was noticeably hotter and smelled burnt.

 

[osufans]

ok, so driving home tonite the noise kept returning, so i tried a few things to see if anything affected it. sure enough, pulling up the e-brake while it was making noise caused it to get worse, and even cause some serious vibration.

it sounded like it was the right rear, so when i got home i tore it apart, and discovered the liners had fallen off the shoes of the e-brake.

i cleaned out the brake area, and put it all back together. it's gonna need brakes all around so i just left the rear shoes in without the liners for now. hopefully problem solved!

 

[LibertyFever]

Glad you found the cause of your problem and thanks for posting it.

 

[osufans]

yeah, you have no idea how loud and disconcerting this noise was.....i was really afraid it was something much worse. glad it turned out to be a simple fix.

so far so good. no noise today on my drive in, so i think we're in the clear.

thanks for all the input and suggestions!