2nd Gen Non-Engine/Transmission Mysterious clunk

[Makensmoke]

Take off from a stop and it feels like the spare tire is loose, sounds like a metal on metal clunk. Only does it when stepping on the gas taking off from a stop. Have checked everything and spend thousands looking for it over the last year (seems everyone has a maybe its this). Thought i'd try posting again.

 

[JGK]

Have you got overload springs? This is a set that stacks on top of the main set and often has a spacer between the main set and these. The helper springs bump up against stops at each end bolted to the frame. If you load the bed with enough weight such the springs are close to the stops, a minor road bump or the twisting of the axle (axle wrap) at take off can cause contact and make a bump sound like a loose spare. Most stops have a hard rubber cushion that slips over them, but they can become harder over time and make noise. Mine are doing it these days with 600 lbs of sand in the back for winter traction.



Jump up and down on the rear bumper and see if you can make it thump.



Just a thought,

-Jay

 

[tajensen]

I think I'm hearing the same clunk in my truck that you've described for yours. It started a couple years ago and would only happen when I came to an abrupt stop while in reverse. Now it happens when I start rolling from a dead stop and also while turning at slow speeds. I'm going to see if the bushing from these guys (http://rocksolidramtrucksteering.com/) will help fix the problem. It's frustrating enough trying to fix a problem once you've figured out what to fix, let alone trying to locate a mysterious clunk somewhere on your truck .

 

[Makensmoke]

I've got only 4 leafs, the bottom being a short one with rubber pads on the ends. The pads do make contact with the next up leaf. So no, I must not have overloads. The leafs are fanned out just a whisker but after multiple through inspections in the truck I can't see that any are fractured making the axle wrap abnormally.



One time last winter I hung my head out the door looking under the truck while my friend gave it the gas, it looked like when the clunk clunked the pinion shifted up, but i can't guarantee that, i was in fear of my life at the time.



One of the shops wired the truck up and the mechanic rode with me while I made it clunk and listeded to some headphones. He said it sounded loudest at the pinion. The dealer took the rearend apart the next week and said nothing was out of spec but some axle bearings, so he replaced them and the clunk is still there. They actually gave up, the dealer said they didn't know what to do next. They must have noticed my anger.



As long as this is long as heck i'm going to keep going. Last winter I removed my xfer case to install a new shifter fork. When doing this I noticed the transmission bolts to xfer case had come a little loose and the bolt holes were a little bit out of round. Thought I had it dicked. And did, no clunk for about 1500 miles, then slowly came back and it is full fledged now again. Bolts are still tight though and no tracks at all of that flange moving.

 

[Matt42]

As long as this is long as heck i'm going to keep going. Last winter I removed my xfer case to install a new shifter fork. When doing this I noticed the transmission bolts to xfer case had come a little loose and the bolt holes were a little bit out of round. Thought I had it dicked. And did, no clunk for about 1500 miles, then slowly came back and it is full fledged now again. Bolts are still tight though and no tracks at all of that flange moving.



[/QUOTE]



I think you are on to something here.



I have had a similar clunk, but from the front. It turned out to be the curbside track bar bolt being slightly under torque.

 

[Makensmoke]

Funny to hear you say that Matt. I had my left side bushings replaced last winter, and now my right side is also clunking when flexed a certain way. I'm not too concerned though I bought all bushings last winter and have the right sides on the bench, just never put them in... now i'm sure they're seized, but atleast I know what that clunk is.



My mysterious clunk is more of a give it gas and . 25 seconds later it clunks. (not sure on the . 25) And if I have weight in the box it takes a bit longer??? The bushings clunk as soon as the suspension moves, right?





Thanks for the reply, i'm not getting too much feedback, again. I'm sure its tuff to diagnose not being in the truck, just hoping for someone who've had the problem share their findings.

 

[tabell]

I slowly had clunk develop about 10k after changing my front rotors. It continually got worse after 50K and 2 years i was inspecting my ujoints and found out the rotor had worn the lugs down a little so it would shift and create a clunk during turning and backing up. The reason this happend was the lugs weren't fully pressed into the rotor.

 

[Makensmoke]

tabell i've changed my rotors as well and thought they came with new lugs allready pressed in them. ? I'll double check though. Thanks.

 

[McCRam]

Just a couple of WAGs. It might be the drums sticking and releasing. Or maybe the torque converter trying to lockup. Did you check the driveshaft for worn slip yokes and Ujoints? Does it do it in 4wd?



Can you get it up on jack stands or a lift? If you could duplicate the problem with the tires off the ground someone might see or hear the problem better under the truck.



Good luck. I'll be curious to hear if you find a solution.

 

[Makensmoke]

McRam i've looked over the shoes and had a tech look at them thinking the same thing, i'm not convinced thats out of the question, but everything looks normal looking at them. I plan to replace the good ujoints next, MAYBE there is a slight tweek causing them to pull wrongly when the torque is highest (highly doubt it but i'm shooting from the hip here, totally). I have gotten it to do it in 4wd, its alot shorter of a clunk though, 2wd is a longer "slap" like the tailgate falling, 4wd is a quicker version. Weight in the box (enough to put it on the overloads... thinking its a spring issue) is a longer delay from giving it the gas to when the "tailgate falls". I've even gotten it to do it with the front end jacked up on my floor jack in the driveway, I bent the heck out of the jack when it fell off... but its one more piece of the puzzle. We have a pit at work for changing oil in the big rigs, i'd like to straddle it and make it happen. With all the politics in our big company i'm sure someone would squeal because of its being unsafe. Keep the ideas coming, i'll check the drums again this weekend.



Thanks!

 

[McCRam]

To eliminate the springs as a source of the noise, you could use a bottle jack or something between the axle and frame on both sides. Do it in a way that all the weight is on the jack and not the springs. Or maybe a block between the bump stops.



Is the clunk really as loud as the tailgate dropping, or just sounds like.

 

[Makensmoke]

Blocking the axle up will eliminate up and down spring movement, but what about axle wrap? My whole ujoint theory is in part of this possibly being axle wrap and the pinion springing up as the axle twists. The clunk feels more than sounds like the tailgate falling. Its not very sharp feeling, kindof a thud, like the straps "springing" slightly as they catch the gate. The noise sounds like very sloppy splines, which is a definate clunk, but not as loud of a clunk as when the bushings were out of the front axle arms.



Do you still think this sounds like a possible torque converter? Was thinking. When I was at the dealer I showed concern about the lag from when I gas it to when it actually goes. It is rediculous if you ask me compared to friends new Chevy. I blame the turbo, but i've driven alot of diesels that have 200+k on there turbo and they don't lag to this extreme. (plus I don't blow alot of black smoke... take off or wot) So i'm talking myself out of that. The dealer told me they figured it was the torque converter failing. But they are really a bunch of young greenies so I tabled it and learned to deal with it. It is in the center of the truck, like the techs noise detector diagnosed... ?



Dodge replaced the transmission (converter too?) at around 70K (almost 130k ago).

 

[AKAMAC]

Like stated above, it sounds like the slip-yoke. Since you're going to swap the u-joints

make sure you inspect and grease the splines.

If the yoke is binding the shaft won't "shrink" as the rear end squats. This causes the axle to wrap to relive the pressure. This is also the probable cause of the T-case loosening up. There is a lot of forward force that is being applied where it should be zero.

 

[kparker]

I had a blown out front leaf eye bushing. It was hard to find, but it was a definite source of clanking. Look them over real well. Worth a shot.

 

[McCRam]

If you can't find anything else wrong in the drive shaft, you might want to have someone knowledgable about the tyranny look at it. From your last post it sounds like it might be something to look into. Hopefully some one who knows alot more about auto trannies then I will give you some advise.

 

[RDelissen]

does it also (occasionally) make the sound when shutting off the truck?

If so, it might also be an exhaust hanger or broken exhaust (at a hanger more than likely) ...

just throwing another, simple to check, option out there



BTW: don't ask how I know what it sounds like :-laf

 

[Aaron_A]

Just curious if you have found the cause of this yet. One of the last times I drove my truck I heard a clunk when I pulled away from a stop sign. At first I thought the car behind me bumped into the rear of my truck or the tailgate fell open (sound familiar).

I do know the splines on my driveshaft are getting a little sloppy,but Im not sure if thats the problem.

 

[Makensmoke]

No I haven't yet, but I changed my xfer case fluid the other day (see post My wife thinks its puurty and I greased my ujoints and the clunk seems to be alot less. My ujoints look good but i'm going to replace them. Maybe its them, or internals in the xfer case... ?



I do have some up and down play at the yoke in the tailshaft bearing, but i'm not sold that its excessive, probably about the same as what is at the rear pinion. Neither is leaking fluid.

 

[CoreyPerez]

My 02 was making a noise but i could feel it under my feet. I found my DS upper control arm bushing is good, but the control arm is sliding left and right on it. Not sure if it was supposed to be welded and it broke, but that is the source of my noise.



~P

 

[Makensmoke]

Its been over a year since i've searched for the clunk and only about 6-8k miles have been driven... but, I have decided it is the rear ujoints. They feel tight, but they must get dried out quickly and hang up and bind. I greased the joints a few times before I drove the truck last summer and the clunk hasen't came back. Also a vibration comes around while driving, thats how I determine they are getting ready for grease again. I'll put them back on the list of things to do now that the weather is warming up some.

On the control arms, I also had one bent, and some bushings that were bad... I blamed the couple years I drove it with the front end leveler in without properly centering the axle, it was always twisting on those control arms.