I am trying to find source of a vibration very prominent (bed shakes) from 55 mph and up. I have had the transmission rebuilt, new torque converter, driveshaft balanced 3 times and new U-joints. I have had the differential rebuilt and axel bearings. Wheels and tires road force balanced. most conservative approach is appreciated. I also replaced motor with stock gm 5.7 2 yrs ago.

 

Sounds like severe out of balance to me, did you have it re-checked?

 

Have what rechecked? I am posting here because of all that I have tried invested into it. I would appreciate any conservative efforts I can make in moving forward, thanks

 

Sounds like you have been through nearly everything. You may want to give your rear springs and u bolts a look. I've seen alot of cracked springs. U bolts tend to rust badly where they go through the bracket under the axle tube. Only other thing I can think of is a defective tire that didn't get caught during balancing. Maybe try swapping a spare on each side of the rear and see if it makes a difference.

 

I had the tires rotated 1 week ago when the tires were road force balanced. This vibration occurs also when rear wheels are elevated under jack stands. I have also tried a variety 2 and 4 degree shims under axel.

 

It's a longshot, but do you think an axle shaft could have a kink in the tube? And not having any idea where the axle was rebuilt, was it a quality shop? Having the driveshaft balanced three times I am assuming the trans mount is good, but even that shouldn't cause that heavy of a vibration if it was bad. Only other thing I can think of is check all the mounts all over the truck. If you find a fix, please get back to us. I'm a bit curious.

 

I have not had any axles rebuilt. Are you referring to the driveshaft? It has not been rebuilt, however I have also used a friends driveshaft to compare without difference. The motor mounts and transmission mounts have been replaced. Have any of you installed a torque converter that was unbalanced? or installed a motor that was unbalanced?.I am curious as well this has been an issue I have tried resolving for over 2 yrs.

 

Ok, I didn't read this in the original post. I assume you have the same issue with either set of wheels on the rear.

 

Having the wheels and tires road force balanced I was assured if there were any defects in the wheels and tires This would be noticed.

 

All I can say it sounds like an out of balance to me. If you had both front swapped with rear, chances are it isn't wheels.