HELP! Rear-End, Side-to-Side "Clunking" Sound

[BamaDrewski]

Looking for some help or insight here. Yesterday, when slowly driving over a speed bump, there was a “clunking sound” in the rear end of my 2000 T4R (4WD) LTD.

I had a buddy with me who owns a machine shop. We took it to his place and crawled underneath the rig. He asked me to push the rear-end of the truck from side to side. There was a clunking/banging sound when I did this. We raised the truck and checked the rear wheels for wobble (wheel bearing check) and they seemed fine - no wobble at all. No leaks in the rear axle seals (replaced these about 2 years ago too)

I rarely take this truck off road as it is a daily driver for me. To my knowledge, it has never had any heavy off-roading. I have near rear springs (bout 2 years old) and AirLift bags at 15PSI.

Anyone have any clue what this might be? If so, I would welcome the input!

 

[SURF RUNNER]

Are the lower rear control arm mounts (triangular metal pieces) still securely welded to the frame?

 

[ki1022]

I'm gonna guess busted sway-bar link or bad bushings.

 

[shiftmx]

Tighten the two bolts for the lateral trac/pan hard bar. See if that helps.

 

[TCMach]

Mine did this. Tightened up the panhard and it went away. Now its back but I know for a fact all my rear control arm bushings are shot

 

[cj80cruiser]

Ok, so when you say he crawled underneath and asked you to push the rear end around you mean you pushed the body around right?

Look at all your control arms and where they connect to the axle and frame. The panhard like already suggested and it seems a few people have had issues with the rear body mounts. I know steve at sonoransteel sells new body mounts if you cant find OEM.

 

[afg10000]

Have the shocks been replaced? I've had clunking noises from the upper shock mounts coming loose.

 

[Pioww]

I have a 98 with about 138k on it. It had a shock that the top of the shaft was completely gone, no threads or any material into upper shock mount. When ait would go over a big bump or speed bump it would make a bang noise.

Also this vehicle had a bad bearing, due to a seized piston in the rear.

I would check the shocks. It looked fine until I pushed on the shock and it moved, it looked fine on the lift, even though part of the shaft was not there.

Good luck.

 

[GSPRunner]

Mine does this. It's annoying, but it's just the fact that the rear control arm bushings are shot.

 

[BamaDrewski]

Thanks everyone! I am going to jack her up on stands this weekend and check all the things everyone suggested. My buddy scared me when he said it "might be the rear differential" but I think that is a LONG SHOT. I will check the mounts, bushings and everything else and post back.

 

[saurkraut]

Did you ever figure this out? I'm having the same issue. Driver side clunk when it seems the rear goes side to side. I did a quick check of the trac bar since that is the likely cause and it's all tight with no play. Now I'm thinking it might be the control arm bushings. I've got 247k on the clock so they need to be replaced anyway. I havent decided if I'm going to go with an adjustable trac bar yet or not.

 

[MStudt]

People are certainly entitled to their opinions.

I realize that, but I'm trying to save you time. Take my advise as you wish, but keep in mind that the only noise a loose bolt will make is a pinging sound from shifting in a hole. The only way a bolt will clunk is if you have a 1/4" bolt in a 1/2" hole. :thumb:

First place I'd start are with your shocks. They tend to loosen up, and they will make a clunking sound.

 

[saurkraut]

I appreciate the effort.

It's not the shocks since I just put some new 5100's on a few days ago and everything is nice and tight. This has been happening before that and has been gradually getting worse. I also know the sound an incorrect size bolt makes and it's definitely not that either. I have seen where a control arm bolt gets loose and allows the control arm bushing sleeve to slide back and forth on the bolt due to the mounting bracket opening up wider.

 

[MStudt]

I have seen where a control arm bolt gets loose and allows the control arm bushing sleeve to slide back and forth on the bolt due to the mounting bracket opening up wider.

That still shouldn't clunk. You're talking about opening by a 1/16, and that's not really going to get the force you need to get a clunk.

Mess with you exhaust lately? The exhaust pipe goes up and over the rear most cross member. You can get noise from that, and it'll resonate through the car. Maybe check the sway bar bushings on the axle. One could have rotted out, and you'll hear that noise on side to side.

 

[saurkraut]

It's not the sway bar, I removed that after I put the superflex springs in. Not the exhaust either. I live on a 5 mile dirt road with plenty of potholes and washboard and would have heard the exhaust hitting the frame or anything else for that matter, that is a pretty distinctive sound also. All of the hanger bushings are brand new as well. It only happens when the rear swings side to side.

 

[GSPRunner]

Look at your rear control arm bushings. Are they so smoked that you can barely even see them in there? That's my guess. Then order some new rear links from [MENTION=98153]MStudt[/MENTION]

 

[saurkraut]

I can see there is still rubber in there, but they look like they've worked for every 247k miles they've got on them. I'm still going to replace all the bushings when I can with some good polyurethane ones and maybe I will find it then. But I'm hoping I can get it squared away before then.

 

[GSPRunner]

My rig has 250k on it and mine are wasted. Jack the rear end up grab a wheel and shake it side to side and have a friend listen or grab onto the rear link and you should be able to figure it out from there.

 

[saurkraut]

I have done that to both uppers and lowers and nothing noticeable but I dont think that would simulate the weight of the body and everything else on the suspension when everything is cycling so I'm not ruling it out. The only thing that I've been able to find that is loose is I am able to get just a touch of play in the rear wheel when I push and pull it from the top of the tire. My thought on that is wheel bearing and the play is so minute that I'm not convinced that is the issue here. If it were, I'm sure I would have been hearing some squeeling by now.

 

[Nelsonmd]

Ok, don't dismiss the clunk coming from a bushing even if it isn't obviously loose or the bushing shot. Several of us have had a clunk in the trac bar even though they weren't obviously loose or shot. Undertorqueing can cause a clunk when turning.

I suggest re-checking the bushings and especially for full torque on the bolts. Mine was a bit under torqued and the bushing clunked when I turned. I got under there, cleaned it out (IIRC it was the upper bushing) and re-torqued it with loctite making sure to have at least the minimum torque and it has been silent ever since.

It's not the sway bar, I removed that after I put the superflex springs in. Not the exhaust either.

Do you mean you converted to leaf springs and got rid of the trac bar? If that's the case, then obviously it won't be the trac bar bushing.

I agree that the tiny play you feel is likely the bearing. If it isn't humming or anything, then the bearing probably isn't trashed (yet).

I think you need to continue to try to induce the clunk somehow so either you or someone else can feel around to find where the clunk is coming from. That's what it took for me to find my clunk. It wasn't easy to induce; I had to lay under the rear and push the body with my feet. I couldn't push it from the side hard enough to hear the clunk, but laying down did it for me.