drivetrain vibration 86 ram van

I have a vibration in the drivetrain on my 86 B150 Ram van. It starts when I get to between 35 and 40 mph and seems to be worse when making a left turn. I've replaced the tranny mount, taken out the driveshaft (no missing balance weights or signs of damage) and checked and greased the u joints and even replaced all four of the tires. I'm stumped, any ideas? Thanks, Tim

I had the same thing on my 86. It was a u-joint. How ddid you check them? I put my tranny in neutral and rocked the drive shaft. slop-slop. Good luck

Are you sure its a driveline vibration?

Try raising the rear axle on jackstands and spin the wheels at highway speed without moving. A driveline vibration can still be felt, but other problems will not be.

Driveline vibration can come from a bent driveshaft, loose/bad U-joints, bad rear axle bearings, bad engine mounts or loose parts, like an exhaust.

Other sources may be a bent rim, unbalanced wheels/ rotors /drums, bad tie rod ends,or ball joints.

If it truly does get worse on left turns, I would suspect the front wheel bearings.

This is strange, the transmission tailshaft is sitting over to the right side of the crossmember and rubbing against it. It wasn't like that when I replaced the trans. mount. I checked the motor mounts and they seem fine and all the bolts are there. How could the tranny get off set so bad?

This is strange, the transmission tailshaft is sitting over to the right side of the crossmember and rubbing against it. It wasn't like that when I replaced the trans. mount. I checked the motor mounts and they seem fine and all the bolts are there. How could the tranny get off set so bad?

Is the tranny mount ok and all of it's bolts there?

Stevo2. Yeah the two bolts that hold the mount to the tail shaft are in place as well as the horizontal bolt that runs through the mount. One part of the mount has slipped along the rubber that the bolt slides though. I pryed it back to where it should be but the mount needs to be replaced again I guess. Funny 'cause it was only about a month old. I still can't figure out what would make the trans shift over like that.