mcmopar

Hello, I am new to the forum and need some help. I have a 1999 Cherokee XJ. I have a very audible clunking sound when the vehicle is moving, either forward or backward. This clunking sound increases with the speed of movement, wheels rotation. I have put trans in neutral and transfer case in neutral and let the vehicle roll or coast and the clunk is there. Turning the steering either way increases the volume of the clunk.
I have put the vehicle on jackstands and in 2 wheel H there is no clunk, front wheels not rotating. When in 4 wheel H or L there is the clunk and as the throttle is increased the clunk gets louder and if steering wheel is turned, in either direction, the clunking gets worse. This clunking is always in sync with rotation of wheels. I can't determine where it is coming from. What could be the problem? Sorry if this is long but wanted to describe as best I could. Thank you.

PatHenry

How do the rear driveshaft u-joints look? It's a continuous clunk?

mcmopar

Thank you for your reply, It is a continuous clunk with rotation of the wheels, like clunk, clunk, clunk etc. Rear driveshaft u-joints have no slop in them. If I grab the shaft and try to move it there is no play. When the jeep is jacked up, all 4 wheels off the ground, and in rear wheel drive only, there is no clunk or noise at all.

PatHenry

Sorry, I misread that.

You can only get the clunk when the front wheels are moving? Can you get the sound by rotating the front wheels by hand?

Things to check - front driveshaft, front diff, front axle shafts (u-joints), brakes, hubs maybe..

PatHenry

Axle shaft u-joints are suspect #1

mcmopar

I been thinking that also, I have read lots of info about removing the left front but not much mention about removal of the right front. Any thoughts on removing axle on right side?

PatHenry

You don't need to pull the axle to check the u-joints, you can take off the wheel and see the joints and get your hands on the to twist. If they're bad enough to clunk, it should be obvious that they're shot.

As far as removing the passenger side, it's exactly the same process as the driver's side, it's just that the axle shaft is a lot longer so it's more of a pain to get in while being careful not to jam on the axle seals (inside the diff) as you put them back in. Otherwise it's the same idea, 3 hub bolts, 36mm axle nut and cotter pin.. pulls out once the hub is loose, etc.

mcmopar

Thank you PatHenry for your replys. I see no slop in the front axle u-joints, While the jeep was on jack stands, I rotated front wheels and watched the u-joints and the movement was the joint rotating in the bearing caps. I took a small pry bar and could not move the u-joints, I have shaken them and tried to twist and they felt tight. I have twisted the front driveshaft and felt no slop. I am totally baffled. I did run the drive train while on jack stands, in 4 wheel drive, and turned steering all the way to the left, the clunk was loud and the tire/wheel was jumping up/down. Still can not pinpoint the source of the clunk, it resonates throughout the whole jeep. What in the world is causing this? The right side wheel/tire was barely rotating, but I think that is normal.

dzywicki

This sounds like when my axle ujoint failed. One of the sections of the ujoint seized. This was on the drivers side. When the wheel rotated when turning, it made a horrible noise and the ujoint made it through that seized section. There wasn't any play in it that I could tell. I finally tore down the axle and it became pretty obvious what was happening. There really isn't much there on the front axles. Hub bearing, ujoint and axle shaft.

mcmopar

Thank you for your reply, I see no play in the u-joint either but maybe it is seized and clunking through the seized portion. Would that cause the wheel to jump?

PatHenry

A horribly bad wheel hub/bearing might cause a jump, other than that the only things dealing with up/down at the wheel would be the spring, shock or ball joints (possibly but unlikely). If the axle is moving up and down (causing the wheel to move), then the control arms, sway bar etc. may be in play.

However, if the u-joint is seized, then as the wheel turns and the joint is not turning, a wheel that has no weight on it would definitely have a little jump to it since the force required to push through the seized joint is more than the force to move the wheel up and down.

mcmopar

I think we are on to something, No slop in the u-joint because it may have a seized section and as it does not rotate properly, hence the clunk and the wheel/tire jump. What do you folks think?

PatHenry

I think it sounds logical. Once you get the hub and axle separated it will be very obvious if the u-joint is seized - it should rotate smoothly. If the hub is bad, it will be loose or noisy when you spin it by hand.

The other possible source of clunking that is tied to wheel speed would be brake related - like a sticking or loose caliper or super worn rotor - but that wouldn't make the wheel move up/down.

mcmopar

I have it up on jack stands now, the wheel turns freely, by hand, no noise. I am going to tear into it and remove the hub and axle, sure hope I find the problem.

PatHenry

Hmm.... while you're under there, take a peek at the yoke where the front driveshaft connects to the axle and where it connects to the transfer case. Try to wiggle those yokes and see if you can move them up/down side-to-side and in/out at all by hand.
If you have a seized u-joint it seems to me that you'd feel something "off" when spinning the wheel. Did you do both sides?

Are you certain that the clunking isn't one of the accessories on the engine (like a fan hitting or something like that)?