I have had some strange stearing and vibrations occuring at speeds in exccess of 35mph when hitting bumps or manholes in the road. these vibrations are not coming through the stearing but seem to be an up and down movement. I have just completed an exaused list of cures including. Stearing shock(six months ago) Power stearing box(was leaking) ball joint bottom of the drop arm, pan hard rubbers and bolts. On the ramp there seems to be no movement in any other joint. The vibration is viloent enough i think to hit the susension stoppers. HELP.

 

I have the exact same problem. It's so annoying. PLEASE somebody tell me it's an easy fix. I wonder if maybe the springs start wobbling of some sort? but if they're on struts,I dont see how that can happen.

 

Guy's, I have 99 HSE and have chased that rabbit. After drag link,panhard rod, steering damper, etc, what helped most is to tighten down the hex screw on the top of the steering box. It will make the steering a little stiff, but helps on the death wobbles. My theory on the death wobbles is the worm gear in the steering box wears to the point that even the damper can't handle all the slop.

 

If you tighten down the steering gear box adjustment bolt it will cause alot of additional wear if set too tight.
Steve, what year is your truck?
Mike