my truck has been vibrating for a while now, and its steadily getting worse. the vibration occurs mainly while deaccelerating from speeds of 30 mph or above. it does this whether i am using the brakes or just coasting. i have put all new parts in the front end, and had it aligned, and the tires have been balanced. i can't see any missing weights from the driveshaft, and the u-joints don't seem to be bad. i think it is coming from the rear end or driveshaft maybe. funny thing is that when i have some weight on the back, or am hitched to the boat, it almost dissappears. please help, it is driving me nutz and i am starting to not want to drive it.

 

well, i think i have a u-joint going out and maybe a bad center support bearing.

 

Sure sounds like a driveline issue how's the rear end? good wear pattern on the ring gear?

 

Does it go away when you touch the throttle? I would guess carrier bearing on the shaft...

 

rear drive shaft universal next to the diff. The heaver the load the more pressure on the u-joint thats why it disappears. At least thats what it was on mine I could feel it more in the shifter.

 

yeah, its the rearmost u-joint thats bad, which probably led to the driveshaft support bearing problem. and it does pretty much go away while i'm on the throttle. i'm just going to replace all three u-joints and the support bearing on friday with good parts that actually have grease fittings.

 

Mine is opposite of that. It vibrates while on the throttle but goes away when you let off? Any ideas?

 

Ya 2nd that, mine does it when I accelerate slowly, if I just mash on it it's fine, any thoughts?