I'm hoping to get some guidance from others here on the proper alignment and re-installation of the front spline on the rear driveshaft of my 2015 F350.

I removed my rear driveshaft recently (it slipped right out upon removal without any force or resistance), and I'm getting ready to re-install it again this weekend, but I've noticed that one of the grooves between the array of male splines on the shaft itself appears to be slightly different than the rest - it seems to be slightly wider. It even has a white-colored stripe of paint down the full length of the groove as if it were denoting it as being somehow different from the rest?

Problem is, when visually inspecting the splines on the inside of the receiving yoke (the part that the spline fits into), I do NOT see any such differences. In other words, it doesn't appear that there is only ONE way to properly insert the front splined-end of the driveshaft. What am I missing here?

Can anyone shed some light on this for me? Is the front splined-end of the rear driveshaft intended to be inserted into the yoke in ANY position around the dial? Or is there only ONE specific position or orientation that it is intended to be inserted or installed? NOTE: I've seen references elsewhere on-line that seem to indicate the need for proper alignment when there are multiple U-Joints, and maybe this is a part of it (?), but I'm not quite sure which U-Joints to consider or how to interpret such an "alignment".

Anyway, thanks for the help!

 

The one on my F-450 would only go in one way and that keeps the ujoints clocked the same, other wise you'll have a bad vibration.

 

Righto. That certainly seems to be the case on this one too, and balancing or aligning U-Joints makes perfect sense, but I'm not sure how to determine that "one way"? That's the hitch for me at this point. In other words, there must be some way of determining precisely where on the yoke that the one deeper/wider appearing spline on the driveline (the one with the stripe of white paint) inserts.

 

I'm thinking that on mine the slip yoke had a spline missing and that's where the wide one went.

 

Yup, there again, that makes perfect sense, but for the life of me, I just don't see such a thing on the inside of the slip yoke. You'd think it would be readily visible?

The more I think about it, I think I'm gonna try and get a decent cell phone photo of the inside of the slip yoke, so that I can then zoom-in on the thing to get a better look. Its pretty tough to see when actually under the vehicle laying on the garage floor with a drop cord. There's just gotta be a difference in there somewhere.

 

Make sure the front ujoint and slip yoke ujoint are timed the same (in line with each other) and try it, if it doesn't go turn the drive shaft 180 deg and try again.

 

Make sure you "phase" the yokes on the driveshaft. All the yokes on the shafts need to be orientated the same way.

 

Larry,

Thanks for your response. I think I follow what you and others are saying here about the need to "phase" or properly balance/position two or more u-joints, but there is only ONE u-joint on this particular driveshaft and its at the very rear of the shaft where it attaches to the pinion/differential.

 

Destroked,

There is a u-joint on the REAR of the driveshaft itself (where it couples with the pinion), and there is another u-joint ahead-of (in front of) the slip joint yoke, but there is no u-joint on the FRONT of the driveshaft, only the spline. Consequently, the only TWO u-joints that really could be "balanced" or co-aligned would be those two.

 

Ok mine has a short mid shaft that goes from the tcase to a carrier bearing and the slip yoke splines to that shaft. Sounds like your slip yoke splines to the rear shaft, if so then align the two ujoints and see if it will go together, if not turn the slip yoke 180 deg and try again.

 

Yup, exactly. The slip yoke splines on mine to the 'front' of the driveline.

I think I'll be able to get a good inside photo of the slip yoke by morning sometime, and that should help me determine if there's something I've missed, like a wider slot or groove (a so-called "double row") in there that needs to be aligned somehow with certain grooves or splines on driveline. At that time, I'll get a better look at things and I'll also be able to attempt the 180-degree approach.

Until then, many thanx!

 

You guy's have all nailed it. Excellent advise everyone ... !!!
It's called keeping them IN-PHASE, meaning inline with each other.

 

Thanks stufarmer! But for me, the question still remains . . . what constitutes "in-phase"? In other words, what specific orientation of the two u-joints (i.e., slip yoke and rear of driveline), do I need to achieve?

For example, should they both be facing the same, such that they appear the same when viewed from the left or right? Or should they be offset relative to one another by 180-degrees? Etc. That's the part that is unclear to me.

 

Think of the yoke on the rear shaft as a letter T, then view the slip yoke as another letter T, now put the long ends of the T's towards each other making the letter I. that's what you want the dive shaft to look like when in goes together.
There's only 4 ways the ujoints it will line up and it will only slide together one of those ways.

 

It may slide together all of those ways. U-joints are phased in pairs, and well... a 2-piece driveshaft has 3 u-joints (1.5 pairs). Which means it is never completely in phase.



you should have one shaft with two yokes on it. Each yoke connected to the shaft should be the same way; forming an I and not a +.

No matter what folks say, that third yoke can be any which way it wants and it won't matter... This is because the front shaft (the one with the single u-joint) is almost nearly in line with the output shaft from the transmission/t-case. This shaft is just an extension of the output shaft, and meant to stay inline with the output shaft. It doesn't have a counter-yoke to remove the vibration it can put into the system. That's why 2-piece drive shafts surge on high-torque acceleration. The engine-transmission move, and put an angle on the front u-joint. When cruising, this angle is 0.



What phasing does is use the second u-joint to negate the output variation seen above. This is the principal that Double Cardan CV joints use. The advantage is that there is very little rotating mass between the phased joints in a DCCV joint. Which is where the surge would be felt.

With that said. Convention is to keep the I configuration for the splined shaft, where the yokes connected to the shaft are facing the same way.