D/ZF 6 speed driveshaft wobble...

manytranny · December 10, 2003

Thought I would get some input on this one...

My truck has a pretty good driveshaft wobble from 0-13 or so in second gear. I would say that it is pretty noticeable.

I had to get a few loads of topsoil today for a little landscaping. I rented a trailer, and loaded it down with 3 yards of dirt. The load was poorly distributed. Maybe the loader wanted me to have an easy job, because he loaded it mostly in the back of the trailer. Left me with at least -300 lbs tongue weight. I guessed the load to be right around 5000 lbs.

I would start in first gear, and there was a little wobble, but not too bad. Im not in that gear long anyway. Then when I hit second, and get on it, I get a big wobble and shake. It will stick around until about 2500 rpm, or 13 mph. Im not really punching it either. I was accelerating gently. I had 5k lbs behind me with no brakes, so I was not on it...

This is something that has been with the truck since new. Happens when unloaded, and gradually goes away with increased payload. (I assume because of changing driveline angles and what not)

It is quite troubling. Cant be good for things. At the end of this trip, I have to climb a 1/4 mile HILL that is in excess of 25% grade. Its a steep sucker. I was in second gear at 2800 rpm, near WOT, and 20 pounds of boost for most of it. No wobble at that speed, but accelerating up to it, it was pretty bad. So bad that the rears on the truck began to spin. Almost had to stop and go to 4 lo.

Anyway, this has turned into a long post. Any thoughts? I know that some Allison owners got a free one piecer, but Im pretty sure that doesnt apply to a ZFer...

got dirt · December 11, 2003

Is your truck lifted? I had a similar problem. My truck is lifted and the carrier bearing damping rubber was wore out. The reason it wore so quickly is when Chevy lifted the truck they didn't check driveline angles. New carrier bearing and dropped the carrier about 3/4 of a inch and the problemwas solved.