Vibration issues

[daking]

I know there are a lot of drive shaft vibration posts already, but most deal with lifted trucks.

 

nineteen hundred & eighty seven Jeep Comanche 4X2 with I6 4.0

 

Stock height, new tires (balanced), new U-Joints, new transmission mount.

 

I few weeks ago I had bad vibration at speed. My transmission mount was missing all the bolts, and all the rubber was ripped. I replaced the transmission mount and u-joints. Truck drove great after that. Slight vibration at speeds above 85 (90 or so), but, hey it is an ol' truck..

 

Now, it has a awful vibration at any speed above 30. different then the last time I had vibration issues.

 

The drive-shaft that comes out of the tail shaft of the transmission wiggles. I think there is a bearing in the tail shaft of the transmission. Can anyone confirm that?

 

 

Thanks

[mountainman]

Who did the U joint replace? did they change the front joint?

[daking]

yea, I changed both U-Joints. It only has a rear drive shaft.

[HOrnbrod]

I know there are a lot of drive shaft vibration posts already, but most deal with lifted trucks.

 

nineteen hundred & eighty seven Jeep Comanche 4X2 with I6 4.0

 

Stock height, new tires (balanced), new U-Joints, new transmission mount.

 

I few weeks ago I had bad vibration at speed. My transmission mount was missing all the bolts, and all the rubber was ripped. I replaced the transmission mount and u-joints. Truck drove great after that. Slight vibration at speeds above 85 (90 or so), but, hey it is an ol' truck..

 

Now, it has a awful vibration at any speed above 30. different then the last time I had vibration issues.

 

The drive-shaft that comes out of the tail shaft of the transmission wiggles. I think there is a bearing in the tail shaft of the transmission. Can anyone confirm that? Thanks

 

AW4 transmission? If so it's probably the bushing in the tail piece extension.

 

http://www.comancheclub.com/forums/viewtopic.php?f=2&t=35035&p=344650&hilit=extension+bushing#p344650

[opsled]

I've had an axle yoke with the little ears that hold the U joint centered worn enough to allow the shaft to rotate off center. Will cause weird vibrations. Out of balance or bent shafts can too. Don't assume the shaft is good even if it was OK before you changed joints.

 

opsled