Low RPM vibrations after fixing U-Joints!

I have 112,000 miles on my truck. My truck is having serious vibration issues. I replaced the tires, had them balanced and aligned. After that my truck still wanted to vibrate. The vibration only happened in low gear when accelerating and going up small hills. I recently discovered two out of three U-Joints were bad. I just replaced all three U-Joints. Well... most of the vibration is gone but once in a while there is still a vibration when accelerating.

some of the following advice was given to fix the problem.... Can anybody help me?

- Flush and change the transmission fluid?
- Rotate my drive shaft 180 degrees?

Does anybody have the answer?

 

Do you have a center carrier bearing in the drive shaft?

 

I would be very suspicious of the new tires and the balance job. Recheck, maybe at a different shop.

Mike

 

Did you mark the position if the drive shaft prior to removal, and ensure it went back in the same way?

Are you sure your u joints are in phase?
http://www.pirate4x4.com/tech/billavista/PR-shaft/index2.html
^^^info on phase^^^

 

+1

 

Yes... When pulling off the drive shaft the center bearing seemed fine. However , the middle u-joint was fine and the other 2 joints were rusted.

 

It seems to be good. the only thing I can think of is taking it apart and rotating the shaft a 180 degrees?

it is awkward, it only shakes around 1,500 rpms while going up hills...

Any other theories?

 

mines does this to.. almost sounds like an engine knock.. haven't figured it out yet

 

heh I've only got 3000 miles and mine has a vibration too

 

Yes I do. I took the driveshaft off again and looked it over. Everything seems pretty smooth. i am going to take the middle U-Joint apart again and rotate 180 degrees and try again. If that does not work ill call and have it rebalanced or have my transmission flushed. It is driving me insane!