Drive shaft question on position & balancing

[VAL]

I've been seeing videos on u-joint replacement, and I notice that its recommended to mark the shaft and the yoke, for reinstalling the shaft in the same position. My question is why? If the drive shaft is balanced, what is it that takes it out of balance, if its put on 180* the other way on the yoke?

 

[PrairieDrifter]

The weight on each side of the yoke may be different, it's more important in the double cardan u joints and two piece driveshaft setups due to the fact that the weights have to be aligned for it to have its proper balance, some people say it's just a good thing to do just to make sure you dont create a new problem. Personally I would just mark it to save the headache and not have to do it over again

 

[MadOgre]

You already figured it out Val! It doesn't make one bit of difference!. The drive shaft is balanced separate from the transmission or transfer case or rear end. So it is impossible for u joint clocking to any of those components to matter when it comes to drive shaft balancing.

I never ever mark mine and they have gone in both ways multiple times and I have never had a vibration issue.

Its just an old wives tale that you should mark it!

It absolutely defies logic and physics that it can cause a vibration.

 

[PrairieDrifter]

I've seen some wierd things haha

 

[MadOgre]

When changing u joints it does matter. So definitely mark it in this case as the entire driveshaft is rotated when being balanced.

 

[MadOgre]

Oh sorry I misunderstood Vals original question. Yes mark when doing u joints. NO don't mark when removing driveshaft LOL sorry for confusion

 

[VAL]

I've never seen a driveshaft being balanced, didn't know they were balanced with the u-joints installed. A few years ago I replaced the u-joints on my shaft(the diff yoke and the slip joint yoke) didn't realize there was a science to the clocking of the u-joints. I had a vibration issue after that, but I installed a transfer case drop kit, and the vibration went away.

 

[PrairieDrifter]

I've never seen a driveshaft being balanced, didn't know they were balanced with the u-joints installed. A few years ago I replaced the u-joints on my shaft(the diff yoke and the slip joint yoke) didn't realize there was a science to the clocking of the u-joints. I had a vibration issue after that, but I installed a transfer case drop kit, and the vibration went away.

I was taught at work to do it then also at school. And your vibration may have went away after the transfer case drop due to the angle of the driveshaft being too great, and you might have got lucky and put the yoke back the original way, it's a 50/50 haha