I have a 2500HD/8.1/Allison/2WD

At 45mph to 55mph I get a disturbing driveline vibration. It's really bad ...

I know it driveline because ...

New wheels
New tires
Balanced 3 different times at 2 different shops
Goes away under hard acceleration
Gets really bad when deccelerating

The trans mount appears to be fine, the carrier bearing appears to be fine and all the u-joints appear to be fine. Nothing unusual.

So, I am giving serious thought to removing the 2 piece shaft and having it balanced.

Before I go to this trouble, any thoughts?

 

I've had a vibration in my truck since new, and the only thing I haven't tried is gettig the d/s balanced. Might be the solution that we're looking for.

I'm getting a new d/s whenever I put the 80E in.

 

so it stops vibrating over 55 ? if the driveshaft is out of balance it should get worse as you go faster. if it disappears under hard accel it sounds like a part that moves, like a u joint. or a part that is loose and should'nt be [ is held in position by torque under accel] check the u-joints again for play, and the carrier bearing. my carrier was loose 8 mos after my lift, i got under there and pushed on it a bunch of times and it would'nt move, must have had some tension on it. the last time i must have pushed on it right and hard enough cause sure as s-it it was loose enough to make noise noise when accel and decel. e

 

Thanks for the input ... I'll look again.

I thought the same thing and the reason I checked everything.

The U-joints visually look fine. They are dry and the seals appear to be in tact. Anyway I can check them mechanically?

I did notice that the center carrirer bearing has an outer housing, a rubber isolator and then the bearing itself. When I shook the drive shaft back and forth looking for movement, the rubber isolator would shift, exposing holes or slits in the rubber. They appeared to be smooth and factory as they were uniform in length and the edges were smooth. Grasping at straws ... is this normal as well?

I put a wrench on all the mounting bolts and nuts and all were tight.