I'm going to pull my rear driveshaft today so I can grease the slip yoke. I know I need to mark the rear u-joints and yoke so I put it back in the same orientation. How about the front? Do I have to mark the splined TC output shaft as well, or does that end not matter for keeping it aligned the same way?

While we're on the subject, why is it important to install the rear u-joints and yoke in the same position instead of flipped 180 degrees? It would still be the same angle, right?

 

I suppose the short answer is that the Jeep FSM states that's how it should be done.

It might make a difference if you have worn-in u-joints that might get unhappy if they are not put back into their original mating position.

Besides making sure that the shaft itself remains in its original orientation (between the slip yoke portion and the main shaft), how it is installed between the output shaft of the transfer case and the pinion at the differential doesn't make a whole lot of difference. The shaft is only balanced to itself. It is not balanced in any type of relationship to the transfer case output or differential.

So my opinion is that if I take the shaft out to do a job, and I am not changing u-joints, then I will put it back in just as I pulled it out (marking it, by the book, if necessary). However, if I am replacing the u-joints, then I will put it back in whichever way. Which I have done in the past, with no problems.

 

Could a swore it has a double tooth that makes it only slide in one orientation.

 

At least on my 96 that is not the case. In fact, it took a couple of tries because I would get it on the wrong tooth and it wouldn't quite line up with the yoke at the differential. I didn't have the vehicle in the air, so I couldn't just rotate the tires to get the yoke to match up. I had to slide the shaft out of the slip, rotate ever so little, and try the next tooth till I got it.

 

i just went through this with a three piece shaft with two carrier bearings and replaced all the ujoints (8 of them on that rig including the front shaft and front hubs) and carriers...

your information above will suffice- one piece you don't have to worry about balance or orientation (in phase, out of phase)... but i write this to add this much, because it is often overlooked, and though you'll haplessly get it right more often than you could get it wrong- make sure the joints are centered in their cradles. we're only talking 1/8th inch or less, which is only slightly possible- but enough to cause imbalance and headaches.

also, if you're replacing with serviceable ujoints, make sure the zerk points to the shaft not the yoke.

 

i never marked any of my driveshaft when removing them and have had no issues. i clean the caps and remove any rust or debris and reinstall it.

if your u joints or yoke are worn and/or the FSM specifically calls for it, then go ahead and do it just to make sure, but in my experience it really doesn't matter that much.

 

I do believe you are correct. They do have a tooth on the drive shaft, on the transmission side, that only lets it go on one way.