Highway Bounce

[PearceTrucking]

2002 Ford F350 4x4 single rear wheel axle. I have a terrible problem with what I would call "highway bounce". At an exact certain speed (66mph) my truck rear end seems to "bounce" or vibrate. This is most pronounced when I am coming back from a load with an empty trailer. When loaded (20,000lbs) I don't notice it at all. But when coming home with an empty trailer and moving through the 63 to 68 mph range, it is violent and will beat your guts out. Abviously I try to avoid this speed as much as possible. My tires were new this winter and have been rechecked for balance and runout and all is fine with the tires. I cant blame it on the trailer as I pull 1 of 20 different trailers each week. When I am not pulling a trailer at all, it does not bounce as bad, more of a vibration at that speed, but enough to let me know it is the truck and not the trailer as it is still present with no trailer. Anyone heard of this? Any ideas or fixes? New Shocks? Anything? Thanks in advance.

[fourx4forfun]

hah, mine had a bit of a vibration but the front tires on her were chewed up from bad shocks so i believe thats my problem. dad has a ranger and swears it has a vibration that drives him batty, he tried lemon law on em, they took him all the way to arbitration with it, still has a vibration, someone at the dealer accidentally left a ford problem sheet in the truck noting the problem on 4 cyl rangers.

[gregor]

Have you checked the U-joints? I just had a U-joint go out on mine. It would only vibrate at certain speeds/rpm's.

[99 7.3]

i've heard of cars doingint his before. getting to a certain speed and that vibrating. how long have u had the truck? has the truck always done this? or could it possibly have to do w/ ur rack (causing vibration) and when a trailer is hooked up it just magnifies it.

[straycat]

I agree with Gregor, u-joint or a tire coming apart. Sometimes the inner belts separate, especially in heavy weight situations. Lift the back of the truck up and spin the wheels and you will know if it's a tire going bad on you.

Gord.

[Hayman]

with Gregor & Gord i had the same vibration at a certain speed on a older ford and it was the u joint also have of a inside of the side wall separating and causing the same scenario.