violent wobble in steering AND shifter

[pathfinder72]

Hi, New to the forum. Have a mysterious problem with my 97 one ton dump with 7.3... very occasionally, I will experience a wobble (at various speeds above 30) that quickly turns violent, with the entire front of the truck violently shaking, including the shifter?? and no matter how hard I hang on, I can't dampen the shifter. I can understand if the problem is in the steering, or bad shocks, out of alignment, etc, but why would it be related to the transmission? This problem seems to occur when the truck is empty and relatively low on fuel- I pull over and start out again, no problem for maybe 10 miles, then it starts again- seems worse on bumpy roads. With full tanks, or a load in the dumper, or pulling a load, no problems. It's only happened once in the last 500 miles, until yesterday, when it occurred about 10 times, then stopped.
The front tires are worn in a cupped fashion, I assume from so much weight being on the back most of the driving time. I could rotate the tires and see if that makes a difference, but why is the seldom-occurring wobble related to the shaking shifter? I'm not a wrench-Have driven trucks a good portion of my life, never owned one and never worked on one.

[vitalidle]

Hmm well cupped tires can happen from not rotating tires or maybe your ball joints are bad. But you say its in the drivtrain right? Maybe you have a bad u-joint going causing vibration. Not really sure someone will chime in with a good answer!

[SMKSTAX]

Try the tire thing, that could shake the front end. How are your engine and tranny mounts? Just a thought.

[NOVAJOE105]

MAy wann pull the driveshaft and check the u-joints and Carrier bearing. Try the tire rotation too if it feels like its more in the steering at first. Good luck and let us know what you find.

[pathfinder72]

The steering wobble starts first, then when it's shaking hard from bad to violent, the shifter shakes side to side- but this happened only once before, then stopped for about 500 miles, until yesterday. If it was engine mounts, u-joint, etc one would expect it to happen all the time, right? - but then I'm not a truck mechanic, what do I know...how can whatever is causing the shaking front wheels to also affect the shifter?

[SMKSTAX]

I know on my 97 just going over rough roads shakes my shifter like crazy. Maybe it's no big deal?

[NOVAJOE105]

Check all of the linkages in the front end for looseness. Also check for a broken belt in the tires. If the front end is shaking violently, it can cause the whole drivetrain to shake like that since it is all bolted to the front frame.

[stewy]

I had a bad tranny mount that caused a problem like that once, it was the rubber mount on the tail end of the tranny. the drive train would move out of alignment and it was like the truck was posessed.

[Nick]

Hey guys I have a 96 that does the same thing. I would like to know is your tanny manual? If it is I think the problem is the dual mass flywheel that is coming apart inside the tranny. I am going to replace my clutch carrier and inspect the u joints and then go from there.

[460+]

If you havent fixed it, try haveing someone shake the steering wheel left to right quickly. Look at the tie rod end for any movement, if none look at the track bar, usually on a straight axle that is the problem.