Rotate the tires. See what happens.

If your control arm bushings squeak, they are prolly bad.

 

I would check tire balance as well. Is there a particular speed where the bouncing begins/ends? How about flat spots on tires? I chased that for a while several years ago. Darn cheap tires.........

 

I have rotated the tires and had them balanced twice. came back good each time. Running BF mud terrains. Bought them new after thinking my super swampers were causing the problem. I have replaced all u joints,ball joints, new shocks, new track bar, new wheel bearings and hubs. drive shafts checked and balanced, Added a dual steering stabilizer, Had 3 alignments done ( All were fine). New rotors and pads. The only thing I haven't replaced is the bushings on the control arms that squeek. Three differant shops and they find nothing wrong with the front end and everything is tight. Ran my friends rims and tires on my truck and it did the same thing.
As for when it happens it comes and goes. You start to notice on the highway around 45 it may start bouncing and then it goes away and comes back at any speed. some stretches of road I can do 70 plus and no bouncing and other times it will. The truck doesn't pull left or right and drives straight. Just starts bouncing for no reason.

** I do have a small exhaust leak at the manifold that's been there since I had the new engine put in and that's also the time I noticed the bouncing ******

 

Do the bushings on the control arms just squeak or are they in crappy shape? I wonder if there could be some play in the bushings causing a problem...

 

they look pretty beat up, rusty and squeaky bushings. I spayed them with silicone a few times and the squeaking stops. probably change them this weekend

 

I've read somewhere, possibly on DF, that worn out bushing can sometimes allow play in the control arm causing issues.

My pop in law had some worn out leaf spring bushings on his '88 RamCharger (you wouldn't believe the crap he went through to get new ones) when he put it in reverse you could see the play in the axle, it moved a good 2".

 

Bringing back an oldie. Its been a while but I put all new Munroe shocks on along with hell bent steal spacers. The ride did get better but I feel this was the result of better shocks. I still have the vibration/wobble and cant figure it out. The truck doesnt pull left of right drives nice and straight. I feel it in my feet more than anything. Im starting to wonder if its the Ujoints in the front end. I thought they were replaced when I purchased the truck but maybe not. Just got a inspection and alignment and everything was tight. Anyone else think its the control arms or the u-joints?

 

Have you tried rotating your tires, and see if the vibration changes?

 

I have rotated them. Fronts to back, back to front and cross rotation of the fronts. Nothing changed. I even tried my buddies stock rims and tires from the same exact model and year dodge. Mine still vibrated and bounced and his was smooth as glass running my wheels and tires. Been dealing with this for almost two years. I noticed it when I ran stock rims and tires but it was very slight and thought the tires were the cause since they were all dry rot, figured this caused them to be unstable. I bought new rims and tires and the bigger tires amplified the vibration and bouncing even more.

 

First, hello all - been away for a while.

I remember this thread, and I just re-read the whole thing. Unless I missed it, I don't think you've ruled out a bent rear axle shaft. I know that doesn't fit with your observation that the vibration started when you put on the Super Swampers, but I think you've swapped tires and wheels around enough times to rule out anything having to do with them.

I keep coming back to your describing a "bouncing". To me, that means some rotating mass is out of balance, creating an up-and-down force. Given what you've replaced on this truck, one of the only things left is the axle shafts. I guess it's theoretically possible that a drum could be so poorly manufactured and out of balance that it could cause this problem, but it would be the first I've heard of it.

You mentioned that the dealer replaced the front driveshaft before you bought the truck from them. Maybe whatever tweaked the front driveshaft bent a rear axle shaft at the same time. You'd obviously have to yank them out, so how about it guys - does this theory hold enough water to warrant that?