Vibration problem

[Lethal03PS]

I have had a vibration in the truck since I got it. I have balanced the tires and everything and cant get it to go away. Its doesnt really happen til around 65mph and over. And worse going up hill. Its not in the steering wheel at all its more in the seats. Its kinds of stealily worses and gets better while I drive it to. It will shake hard then and correct itself for about 3 seconds then it will get worse again. Over and over again. Could it be U joints? My truck does have a leveling kit on it with 35's, would that be the reason? The truck has 84,000 miles on it now. Im clueless? Anyone with similar problems or maybe someone with a good guess?

[Evil Eye]

U-joints or drive line vibrations would be consistent with RPM's, which isn't what you describe. It shakes how? Left to right in the steering wheel or just up and down? It gets worse going up hill? How did you determine that? The leveling kit might have shifted the axle in front; do you have an adjustable trac bar? Sorry for the barrage of questions, but vibration problems are very difficult to diagnose via the internet...

[460+]

I would check the ujoints, look for rust around the caps. If no visual signs take the drive shaft out and move the joints if they are tight then replace. If nice and free they should be ok.

[Lethal03PS]

Originally Posted by Evil Eye

U-joints or drive line vibrations would be consistent with RPM's, which isn't what you describe. It shakes how? Left to right in the steering wheel or just up and down? It gets worse going up hill? How did you determine that? The leveling kit might have shifted the axle in front; do you have an adjustable trac bar? Sorry for the barrage of questions, but vibration problems are very difficult to diagnose via the internet...

WOW Lot of questions..haha..Its doesnt shake in the steering at all, just in the body. I feel the vibration most in the seats. Seems like when the motor is under a load the vibration worses. Its hard to explain the vibration. It vibrates hard for about 5 seconds and smooths itself back out for 5 seconds, then it vibrates hard again. Like someone is hitting a on and off vibrate switch while im going 65mph+. Thats why its annoying. I dont know much about this leveling kit cause it was on the truck when I got it 7 mos. ago. I was told it was a leveling kit from summit racing. I hope we can figure this out.

[BryanH]

Man this is a big shot in the dark, But since it is NOT in the steering wheel, But under your butt, I personally would start with mounts, First I would check motor mounts, Get someone to give some juice w/ brake on see if your motor lifts at all. Sounds crazy but I've had a cracked motor mount on a gasser which vibrated under load. ( hill or trailer ) Next I would Tranny mount. It could be something this easy! If all good I probably would focus on the pinion angle, Front and back. Have you ever drove it in 4X4 high and does it do the same thing.

Good Luck man. It's just the process or elimination.

[choctaw]

Do you always put a Quarter in it when you start it?

[Lethal03PS]

Ill give some of these a try. My buddy told me it could be pinion angle. We are going to check that this weekend along with u joints.

[towbeast03]

yeah man I get vibrations also but only on take offs. but I have 10 inch lift and 5 of those inches are stupid blocks in the rear....I was told it was the axle wanting to wrap because of those blocks... maybe yours is doing the same, even though you don't have blocks. try some cal tracs or latter bars... hope I was able to help.

[arodrigues]

try getting your injectors checked i just got my truck out of the shop three days ago for the same reason. that was the last thing i though it would be

[Lethal03PS]

Thats wierd, how could injectors cause a vibration...It seems like there is a lot of off the wall things that can throw a vibration. I might just want to take it to a ford dealer.