BX 2250 FWD Drive shaft troubles. Please advise...

[Lspark]

So I have a BX 2250 I use to mow a steep slope with about 900 hrs in it. The other day when I was mowing, I heard some clanging, and after looking, I found that the drive shaft that powers front wheels had detached. Apparently the “roll” pin sheared under pressure and it slipped out. Picked up a pin at local Kubota dlr and put it back on. Thought problem was solved but now I have an odd shudder or vibration in my steering and it is apparent something is not aligned as it should be.

I have read thru some forums and learned that this is not uncommon and it means that I have to “align” the shaft so that the FWD is in synch with RWD. I may be messing up some terminology so bear with me please. After looking it over I simply turned the drive shaft 1/2 way over and realigned the holes in each part of the shaft And put the pin in. It did reduce the vibration, but it is still quite noticeable. On one online forum I noted that one person had my issue exactly and he said that after he installed and got vibration he dismantled and noted a small mark on each shaft that had to be in line and he reinstalled and that solved. he did say the marks were hard to see. They must be !

So I am going to take mine apart again but I started thinking - What do the marks look like and how do you align them. I say this only because it appears the roll pin holes in each shaft should automatically align the shafts as there are only TWO possible positions it could be reassembled !


What am I missing or not understanding ?

Kind of a newb here. Any help is appreciated

 

[tinkerwitheverything]

you don't need marks to put your u joints in phase. When you put the shafts together make sure that the yokes and cross's are all facing / matched up. Eg: the yokes that are on the same shaft have to be sitting with the cups facing up or sideways. They have to be in line. If you have the shaft sitting on the floor then the yoke thats on the front of the shaft make sure the cup is sitting on the floor and the rear yoke has to sit on the shaft the same way. Hope this makes sense.

 

[Henro]

you don't need marks to put your u joints in phase. When you put the shafts together make sure that the yokes and cross's are all facing / matched up. Eg: the yokes that are on the same shaft have to be sitting with the cups facing up or sideways. They have to be in line. If you have the shaft sitting on the floor then the yoke thats on the front of the shaft make sure the cup is sitting on the floor and the rear yoke has to sit on the shaft the same way. Hope this makes sense.

You don’t say which end of the drive shaft the roll pin came out of at the U-joint, but I assume it was at the back end of the drive shaft.

This is because the only way you could’ve noticed this is if the driveshaft actually fell down away from the shaft coming out of the transmission. And the back end has only one roll pin and a long spline.

Putting it back together there’s probably something like a one in 10 chance of getting it right if you don’t know what you’re doing. Just a guess on my part. I’ve been through the same thing a couple years ago.

You need to check online and learn about phasing of U-joints on the drive shaft. It’s not that complicated. But if you don’t know what you’re doing you got about a 10% chance of getting it right.

Chances are really high that you got it wrong! Not a big deal, as you can make it right pretty easily. But do it sooner rather than later!

 

[Lspark]

It is the back one as you describe. I think I understand what I have done wrong. I always keep mine in 4wd and it never occurred to me that putting it into 2wd would allow me to turn the front axle spline to allow lining up the yokes. I had it in 4wd and noted that since both shafts turn symmetrically, the only way it could line up is by the It never occurred to me to shift and see. Does that make sense ?

 

[Henro]

It is the back one as you describe. I think I understand what I have done wrong. I always keep mine in 4wd and it never occurred to me that putting it into 2wd would allow me to turn the front axle spline to allow lining up the yokes. I had it in 4wd and noted that since both shafts turn symmetrically, the only way it could line up is by the It never occurred to me to shift and see. Does that make sense ?

Yes, kind of... But once the driveshaft is off, the front shaft will immediately get out of synch, since the gear ratio is such that the front tires turn a bit faster than the rear tires during normal operation.

There is nothing to ensure you put the thing back together with the u-joints in synch. (like one wider spline, which would force reassembly only one way). Probability says you likely did not. Easy fix once you understand u-joint phasing, which is not difficult.

 

[tinkerwitheverything]

It is the back one as you describe. I think I understand what I have done wrong. I always keep mine in 4wd and it never occurred to me that putting it into 2wd would allow me to turn the front axle spline to allow lining up the yokes. I had it in 4wd and noted that since both shafts turn symmetrically, the only way it could line up is by the It never occurred to me to shift and see. Does that make sense ?

I think so . Just keep the yokes in line and it's good to go. Easy enough to do once you have the idea of how they work.

 

[Lspark]

I think I may need a dummies version of this forum. i was correct in my thought that shifting into 2wd allowed me to turn the front spindle to align. The driveshaft. Embarrassing that it took me 3 attempts to get it right but at least it is now correct. Like I said in previous post, I guess most people use 2wd and 4wd more frequently. I never take mine out if 4wd and since I was trying to align it while in 4wd, there was no way those spindles were going to align.
thanks to everyone who responded.

 

[netxtown]

While I've not spent my whole life fiddling with u-joints, this whole "phasing" thing isall new - and i am hoping - the saving grace to my FWD vibration issue. I replaced both of the U-joints...and tomorrow I will have to climb under and see if the yokes are in alignment.

WHO KNEW !!!??? lol!

PS - this ujoint alignment thing really should be one of those sticky posts. And thanks to all for the great wisdom & advice up above!