Ok I've been fighting the 57mph bed vibration issue now for a while. Tires balanced twice, axel shims, exc. It mostly happens on the driver side. After both summer and winter 20's doing it I thought "hey let's see if the 18" spare does it. And FYI yes it does. :-( . While I was rotating the front tires to the back I grabbed my axel studs and gave them a yank. In and out I get a 1/16th movement and a clunk, I've seen that before on my old Chevy. What I wasn't expecting was a vertical clunk. If I lift up on the axel studs I get a 1/16-1/8 clunk. I am only pulling up maybe 10 foot pounds with the axel tubes supported like in the picture. If some one out there without the bed vibrations could check their truck,,, well that would be down right nice of ya! :-)

 

Ok, well no replies.. I''ve been reading all night on several post about 55mph bed bounce and vibrations. I just read 30+pages of post about the road active suspension RAS. Has anyone with the bed-vib issue thing have their problem solved by the RAS?

 

I have read all the pages in that thread as well. Alot of ECO users have applied this RAS.

i've had the 55mph bounce since day 1. One guy directly in the vendor thread stated his has 95% went away after the RAS was applied.

Mine is worse on the drivers side and I can look in the rearview mirror and see the drivers side rear bed just bobblling up and down. Not as pronounced on the passenger rear.

And only @ 55mph.

I have a regular cab 4x2 however, but I'm thinking that doesn't matter.

 

Anyone else have the 55mph bounce/vibration....Especially in a 4x2 Regular Cab?

 

So it's been over a year since I posted those above pictures and no one has tried to move their axel up and down? Bummer, i've rotated the tires several more times and have taken it to the dealer four more times. They have also rotated and balanced the tires, indexed the drive shaft and checked the runout of the rear axel. So far nothing has fixed the 55 - 60 mph vibration. If anyone has any constructive suggestions I would appreciate it :-)