Ok, so i have a 2006 F150 FX4 with 6" fab tech lift and 35" tires... starting off I noticed some tire wear but figured i would get to it later. Well after a trip to our place in OK on Ruff logging roads. I had a real bad vibration above 40 MPH. Stopped on Monday and had the tires re-balanced and found i had a bad front hub ( hence the tire wear). So i replaced it and checked everything else i could see and nothing else showed any wear of abnormal movement. Put it back on the ground and now from 50 to 60 mph i still get a vibration (feels like in the drive line) but after i get over 60 it clears up and runs smooth until i hit 80 and it comes back even worse............ Does anyone know what else this could be??? i am so stumped with speed how it comes and goes. I know if it was a balance issue it should get worse with speed not clear up and them come back at an even higher speed..... i am about to pull my hair out over this... any HELP would be great.
Thanks

 

Any of your tires have an excessive amount of weight on them from the rebalancing?

 

Nope they only have about 10k miles on them and the wear had just started to be noticeable for about a week and half maybe two before i re-balanced and found and replaced front hub... the tires are already wore back smooth or really close to it.

 

bad u joint is a possibility. Do you know how to do a dry steer test?

 

This does sound like a U-joint problem to me. Can you hear the whistle/whirl of a driveshaft U-joint when driving?

 

To prove it in or out of the drive train drive it to the speed where it occurs and pop it in neutral. If it goes away check the drivetrain. If it stays rotate the tires and see if the vibration moves.

 

I had the same issue and it was the ebrake hardware. One side is engaging just a small amount.

After I drove it for a bit I noticed one rotor was slightly warmer than the other.

 

OK so thanks for all the comments, i felt like it was a drive shaft as well but when i crawled up the first 2 times i didnt feel any play so i moved one. However it got worse yesterday and after the comments on here and my gut feeling i decided too look again. after checking it a 3rd time i noticed one of the caps on the rear yoke looked funny and sure enough it was bad, one ear was almost completely broke off, so glad it didnt come apart going down the road. I went ahead and replaced both last night to be safe and plane to stop on the way home tonight and pick up two more for the front input shaft to make sure all is good since i do have 114k miles on it and have never replace any of the u-joints.
Thanks again for all the help.