Highway vibration - not wheel balance. Please help.

[ThrillerR1]

Looking for some help here. My truck (2006 v8 186k miles) is experiencing a vibration starting at roughly 50mph and stopping at roughly 60 mph. The vibration is worse when I'm accelerating but still noticeable at cruising throttle. I've already tried...

Wheels balanced.
Switched back to OEM wheels
Alignment
New wheel bearings
New CV axles
Inspected driveshafts - no extra play.
No play in the front end either turning or in and out (tie rods / ball joints)
Steering rack bushings appear to be in good shape
Motor mounts appear to be in good shape.

Truck has method racing wheels, 35's, Icon stage 7, RCI skids, CBI and Shrockworks bumpers. The problem didn't start until I installed the CBI rear bumper. That was after I had already lifted the truck and installed the wheels. Everything was perfect until the rear bumper went on, but I can't imagine that causing a problem like this.

Any ideas what could be causing my issue? I've run out of ideas. Thanks in advance!

 

[RedSled]

Looking for some help here. My truck (2006 v8 186k miles) is experiencing a vibration starting at roughly 50mph and stopping at roughly 60 mph. The vibration is worse when I'm accelerating but still noticeable at cruising throttle. I've already tried...

Wheels balanced.
Switched back to OEM wheels
Alignment
New wheel bearings
New CV axles
Inspected driveshafts - no extra play.
No play in the front end either turning or in and out (tie rods / ball joints)
Steering rack bushings appear to be in good shape
Motor mounts appear to be in good shape.

Truck has method racing wheels, 35's, Icon stage 7, RCI skids, CBI and Shrockworks bumpers. The problem didn't start until I installed the CBI rear bumper. That was after I had already lifted the truck and installed the wheels. Everything was perfect until the rear bumper went on, but I can't imagine that causing a problem like this.

Any ideas what could be causing my issue? I've run out of ideas. Thanks in advance!

I would take the bumper off, and see if it is still doing it.

 

[ThrillerR1]

I would take the bumper off, and see if it is still doing it.

At this point I doubt I could do that. The carriers are not coming off and the bumper is a bit to awkward for me to try and remove then reinstall. After installing the front bumper, the feeling in the front end was a lot better but the vibration remains.

 

[ThrillerR1]

Replaced all the U Joints just to see and the vibration is better now but still not gone.

 

[J.F. Sebastian]

Replaced all the U Joints just to see and the vibration is better now but still not gone.

With all the work you've done, there has to be a simple solution to this. Are you sure all your wheels are high speed balanced and your alignment is bang-on? Could a bunch of weight in the rear be causing the front end to lift too much?

 

[ThrillerR1]

With all the work you've done, there has to be a simple solution to this. Are you sure all your wheels are high speed balanced and your alignment is bang-on? Could a bunch of weight in the rear be causing the front end to lift too much?

Vibration is there whether using my OEM wheels or the new ones. I wondered about the weight lifting the front but I just got my Shrockworks front bumper on and issue remains.

Replaced all the U-joints in the drive shafts, it got better but it's still there.