Background: this is a 2003 1500 4x4 auto 5.7l. I've got an ~800lb pop up truck camper on this rig (in case anyone is confused this is NOT a trailer, its a truck camper that pops up so normally the cab over portion is only ~10" tall while on the road). I've had this truck about 5months and probably put 1-2k on it at this point.

I think I'm getting excess vibrations/play in my drive line. When doing 75mph and such at times my four wheel drive shift leaver (on the floor) will rock around a good couple inches which seems excessive. Counsel cup holders will also bounce around too. This is on flat expressway so its not the road transferring things up. Nothing notable happened to cause this and I'm just noticing it since I'm actually getting out in areas of where one can travel at such speeds (previous trips had been in 60mph zones for the most part). A quick inspection underneath doesn't show any obviously worn u joints or a freshly thrown drive shaft weight, etc. Any thoughts on what to check more in depth and how to do so in a driveway setting if possible? Things seem fine at lower speeds. Only other notable item (I think its unrelated but in case its not...) is just before coming to a stop while braking I get some subtle jerking sometimes but I tend to think that is likely a minor rotor issue (either glazing or warping?).

New potential for a bigger trip this summer is coming around and I need to flush out as many gremlins as possible...

 

Do you have any leaf helper springs or airbags in the back? How much does the *** end sag and what is the weight of the LOADED truck w/camper. You cannot go just by dry camper weight, because your def packing cargo inside the thing.

My guess is you have no helper springs nor airbags and your *** end is sagging a bit. This will change your drive line pinion angle and cause vibrations. These vibrations are generally revolution vibrations which are a steady high/low pulses in the floor boards. Anytime you change your ride height by lifting or lowering, the pinion angle changes and could be a culprit.

I would recommend airbags as helpers. stock ride quality and adjustable to user needs. easy install and takes maybe 2hours.

Also, could be your tire out of balance as well as a bad trans mount for the clunking. You need to physically touch the driveshaft for u-joint wear.

 

can you feel it in the steering wheel, or can you feel it in the seat of the truck...it could be a unbalanced drive shaft.."dented"...or maybe tires need to be rotated

 

I'm running ride rite airbags which brings the height back to normal (70psi drivers side, 20psi passenger).

I don't feel anything in the steering wheel. Its more in the chassi and the four wheel drive shift **** shaking back and forth a decent amount.

There isn't any clunking going on though, just vibrations. How best to inspect a tranny mount (pry on it with a bar a bit to see about movement?)?

 

why do you have the driver side set at 70psi and the pass side at 20psi?

 

^^^ offset weight on the camper top I presume???

 

Camper weights more on that side and the gas tank also happens to be on that side, thus the driver side of the truck tends ride a tad lower. In general though with the camper on the truck only squats 1/2"-1" from an unloaded stance.

As for this vibration thing I was leaning towards pulling the shaft and having it checked out, then installing fresh greasable u-joints. Opinions before rolling forward?