Driveline Vibration 20+mph

[EagleStroker]

Need some help to not go insane on this issue. I nearly sold the car because of 'one more problem.'

The car was an every day driver for a few months while I overhauled my truck, and then it sat for about two months. When I went back to drive it I felt a slight vibration. I assumed it was a slight flat spot and went on driving. After about 100-150 miles the vibration increased considerably, to the point the car isn't safe to drive. It comes in about 20 mph and gets increasingly violent shaking the entire car. It does not change with accel/decel, left/right, clutch in or out. No difference with another set of wheels and tires, either.

My impression is it is behind the transmission. First thought was a u joint but they are not whining and have little to no play in them. The driveshaft is a dynotech 1 pc and has only had a couple thousand miles on it. I'm frankly stumped and fed up with problems.

The car sat for another few months as I just had to walk away. We have good weather this weekend so I'm going to do some maintenance and give things another look. Suggestions/questions are what I need, I just need a starting point.

 

[808muscle]

I have a DSS one piece driveshaft. After I installed it I had a vibration around 25-28 mph. I called DSS and they told me to adjust my UCA to lengthen the DS by and 1/8 of an inch. I did and the vibes were all eliminated. My guess would be is it possible your pinion angle is out of whack?

 

[EagleStroker]

This did not show up after install, but I did check the pinion angle as it was a thought.

 

[BruceH]

Need some help to not go insane on this issue. I nearly sold the car because of 'one more problem.'

The car was an every day driver for a few months while I overhauled my truck, and then it sat for about two months. When I went back to drive it I felt a slight vibration. I assumed it was a slight flat spot and went on driving. After about 100-150 miles the vibration increased considerably, to the point the car isn't safe to drive. It comes in about 20 mph and gets increasingly violent shaking the entire car. It does not change with accel/decel, left/right, clutch in or out. No difference with another set of wheels and tires, either.

My impression is it is behind the transmission. First thought was a u joint but they are not whining and have little to no play in them. The driveshaft is a dynotech 1 pc and has only had a couple thousand miles on it. I'm frankly stumped and fed up with problems.

The car sat for another few months as I just had to walk away. We have good weather this weekend so I'm going to do some maintenance and give things another look. Suggestions/questions are what I need, I just need a starting point.

You already changed wheels and tires which would of been the first place I would look. I'd visually inspect the ds with a flashlight and mirror, looking for evidence of missing balance weights or damage to the ds. Next up would be to swap the ds out if possible with a known good one, preferably a stock unit.

It still vibrates with the clutch in and the motor idling provided the speed is high enough, correct?

Edit: Have you checked the rear pinion adapter? It may of loosened.

 

[EagleStroker]

You already changed wheels and tires which would of been the first place I would look. I'd visually inspect the ds with a flashlight and mirror, looking for evidence of missing balance weights or damage to the ds. Next up would be to swap the ds out if possible with a known good one, preferably a stock unit.

It still vibrates with the clutch in and the motor idling provided the speed is high enough, correct?

Edit: Have you checked the rear pinion adapter? It may of loosened.

I've had a different/good d/s in the car just for shits and giggles, same issue. I checked the mount (I think that is what your referring to) when I adjusted the pinion angle using my adjustable UCA.

When climbing around under it yesterday I found the flange coming out of the tailshaft of the transmission has a little play. I know enough to know it shouldn't have any so the car is in the trailer and is going to cost me for more knowledgeable hands on the project. If that's the real problem I may just take it back home and save for a T-56.

 

[doogie]

Good luck getting this figured out Robert!

I know where you can get a low mileage replacement TR3650 if you want to go that route