2006 UD 2000 vibration

[Bsmith8464]

Hello, I have a 2006 UD 2000 with 310k miles. I have a vibration that I can't narrow down. And it could be multiple separate things. For some time the vibration felt like an out of balance tire. I've used balancing beads, traditional weights but nothing seems to help. Brand new tires ride better of course, but you can still feel it. The strange thing is that it's mainly at higher speeds 65 and above. I have found that if I'm running at 70 or 75 and if it's shaking I can let off of the throttle, slow the truck down to 60 and accelerate back up to 70 the vibration will sometimes completely go away. This is the first scenario that I've had for years

Next and most recently I have an either the same vibration getting worse or a new different vibration. It was first noticed when the exhaust brake turns on while decelerating. At times it felt like I was driving on the rumble strip but less severe. I turned off the brake and it's only about half as bad, but still there. I tried shifting to neutral and that almost made it smooth, but I can still barely feel it. I also feel it while accelerating, but it's not all the time. It comes and goes. At times I notice how smooth the truck is riding, but then it will come back. I've checked u joints and they all feel really tight. The carrier bearing has a small amount of play in the bushing, but I read that up to 1/4" is normal. Does anyone have an idea?

Thanks

 

[greasytshirt]

I recently worked on a Hino that had a frozen slip yoke and incorrectly balanced tires. Vibrated like crazy.

For vibration analysis, you need to think about the frequency of the vibration. Lower frequency vibrations are often tires, and higher frequency vibrations are often drive line. I discovered the slip yoke problem while inspecting the u-joints.
Driveline angularity and phasing are also suspect.

Misfire and broken fan blades can cause vibrations, too.