I have a 2003 F350 crew cab long bed 4x4 7.3 with 100,000 mile on it. When you go 50+ mph it gets to bouncing pretty bad in the rear end. The puzzling thing is it doesn't do it continuously or at any particular speed. It does it more on concrete roads than asphalt. I have had the truck for about 6 months, and have been chasing the problem. The things I have done so far are, balanced the tires ( have even changed the wheels and tires with a known good set off my other truck), changed shocks, u joints, changed carrier bearing ( and tried shimming it at varying thicknesses), and balancing the drive shaft. I am quickly running out of things to try,and am growing VERY frustrated. I would very much appreciate any help.

 

LONG BED empty..it will bounce. If you don't tow alot try droppint the air pressure to about 45psi and see if that helps. I always got weight in the rear of mine so i don't have that problem till i'm empty.

 

No need to double post, we will get to you most of the time, LOL!

I replied to the other one.