What’s wrong with my drive shaft?

Is that #### thing bent? Is that even possible? (Go and laugh me out of the community, but that's the one thing I keep looking at...)

 

Howdy Hulld,

Looks to me like the slip yoke was installed 90 degrees off this throws your u-joints out of alignment and will cause vibration and eventual wear-failure of the joint, possible loss of the drive-shaft.

Dave

 

It's out of phase . 90 degrees to be exact

 

Im happy to learn something today.

I know you will not lose your shaft any time soon after it's fixed.

 

Howdy Hulld,

You can take some comfort in knowing that your drive-shaft slip yoke was reinstalled the the BEST wrong position. If it had been installed say 45 degrees off you would have really had problems, I worked in a drive line shop for a while you would not believe how many times someone would take their drive shaft out of a car, truck, motorcycle anything with a drive-shaft, take it apart put new u-joints in, re-install the shaft with the joints out of phase and then bring the vehicle in complain of horrible vibration.

You can install the slip yoke in any position and run the shaft at its maximum rated rpm and NOT have any vibration so long as the entire drive-shaft is in a perfectly straight line. The moment you put an angle on the shaft it will vibrate and the greater the angle the shaft rotates at the greater the vibration. Here is a short video that explains this. Two major causes of drive-shaft vibration are ONE the u-joints being out of phase or TWO the angles at BOTH ends of the center shaft between the u-joints not being the same.

The hardest thing for folks to grasp is that when the drive-shaft operates at and angle the center shaft rotates at DIFFERENT speeds as it rotates, the greater the angle the greater the differential in rotating speed. This is why a drive shaft with only ONE u-joint will ALWAYS vibrate and cause major wear-breakage problems, the driven shaft will rotate at a constant speed, the out put shaft will rotate at varying speeds depending on the angle. In order to have a drive-shaft rotate a steady constant speed you need at least two u-joints one on the driven shaft and one on the out put shaft at the other end of the center shaft.



This video talks more about angles and why they are important.



Dave

 

While you have it out and on the ground. Once you have it all phased, new joints and new center bearing...... take it in and have it all balanced. Then mark it at all points. Next time you remove it just make sure it goes back the same spot.

The yoke that is mis-clocked has infinite splines and can be put back on anywhere. It most likely got botched during a prior bearing replacement. Good luck getting the yoke off. ......Older trucks I have had them rusted on good, gave up heating and pressing and just had a new shaft made up.