I've been doing a lot of research trying to figure out what causes these 04+ F150's beds to shake so bad when going over small bumps, and if anyone has any info, I would love to hear from you, but as a side note, I discovered something interesting. As a cost savings in the production line, FORD as decided to NOT balance the full size spares under your new truck. I checked about 10 new trucks at a dealership, and not one, including mine, had a balanced spare tire. The next time your truck is at the dealership for service, tell them to drop the spare and balance it. I had my dealer do this, and they did it for free. This doesn't sound like a big deal, but if your 200 miles from a service shop, and you put that spare on, your in for a miserable trip. I hope this helps some folks!!

 

Good looking out!

 

I see you're from Michigan, hum, stay off of I-75 from Detroit south and you should be fine. Kidding, well, mostly. Have you checked things like ball joints, tie rods etc? I personally think most new trucks have too small or narrow of tires, however, I've driven only new trucks from 04-08 before they were traded in so I don't have any long term knowledge. They seem fine new, maybe older ones with miles need new shocks?

 

Right on about I-75, Michigan's own paved obstacle course!! I've been researching this problem for quite some time, and this is what I've come up with. In 2004, Ford redesigned this truck, and two of the big changes they advertised heavily really contributed to this shaking. One, they went to the "Hydro-formed" stiff frame. Chevy did it about 6 years ago, and it does make the frame stiffer, but it is brittle, can't be straightened, welded, or fixed. If you damage it in an accident, it's totaled or time for a new frame. Second, they move the springs and shocks way outboard, which combined with the rigid frame, creates a rapid shaking of the bed when you hit a sharp bump on only ONE wheel. For some reason, this new model truck has had all kinds of problems with various harmonic vibration issues. These things can be tricky, because it really depends on the entire combination of moving components to create the harmonic vibrations, so who knows, the right combo of axle, driveshaft, tires wheels, and it could be worse or better. I read a thread from back in 2004 about this issue, which made me feel better because it wasn't just me imagining this, it was real. I love the truck, but man, when you drive the BAD Michigan roads, this thing SHAKES!!! It really needs some ****tail shakers mounted in the back corners of the frame, just like old 68 Camaro convertables had.