[gdotgarrett]

I am totally not concerned about the video. That phenomenon in the video will only occur when the excitation force's (in this case road bumps) frequency (based on distance between bumps and speed of vehicle) reaches the natural frequency of the bed to frame "rubber attach point" and/or rear suspension natural frequency. It's known as resonance and under this condition the suspension can actually begin to further excite the bed bounce issue. Additionally, I think the bed bounce is further exagerated because there appears to be a rubber damping spacer (saw a pic in an older post) in between the bed and the frame at the attach points. Sure the frame bends under torsion as Toyota designed it to, but I think the rubber attach points are allowing the bed to continue to oscillate after the frame returns to its equilibrium condition. Ford chose their "test" speed such that this particular condition occurred with the Tundra. All they had to do was watch the bed as they varied the Tundra speed along this track and then choose the speed that had the most dramatic effect on the bed. My guess is that they were probably trying to find the speed condition where the Tundra left the road like the Chevy, but when it didn't (due to good suspension and frame design) they settled on "mocking" the bed bounce issue. A little slower or faster and the violent bouncing would have significantly decreased. At least the Tundra stayed on the road. The Chevy bounced all over the place. Today during lunch I noticed a 07 silverado has the bed rigidly attached to the frame, no rubber damping like Tundra. There exists a speed at which the shorter wheelbase Ford will also experience this and the Tundra would not.

As far as the talk about real world experiences on bumpy roads (which concerns me the most), I still think it has to do with the rubber dampers in between the bed and frame allowing too much oscillation. I bet if you replaced them with a more stiff rubber spacer it would decrease this continued bouncing after a bump is hit. Even tightening the current bolt that I suppose runs through the rubber spacer would compress the rubber and also probably improve the ride.

Just thought I would share my 2 cents as I have been writing about spacecraft fuel slosh and natural frequencies all morning...

I guess I should add that based on the limited information that I have about the design of the trucks mentioned above and as to the nature of the problems these guys are experiencing on rough highways, this "speculation" could be completely wrong!