BX23 Ujoint / new vibration question

[Ex Five 0]

Hello to all tractoring dudes. I am reaching out to our collective knowledge base to get some answers regarding a repair/operation issue involving my 12 year old 800 hour BX23 TLB.

Sorry for the long story, but I wanted to include as much background data as possible.

The slope of my property requires 4WD use for most areas. Towards the end of last summer, while mowing with a 48 landpride rear mower, I noticed that I had lost drive to my front wheels. A look under the tractor immediately disclosed that I had lost middle Ujoint for the front drive shaft. I backtracked the area that I had mowed but was unable to recover the lost part. I ordered a replacement ujoint assembly and roll pin and completed the simple repair.

The next time I mowed, I noticed a vibration when the 4WD was engaged. Since I had also recently replaced the front tires, I chalked up the vibration to the tread on the new tires (the old set were essentially baloney skins)

Now, I am noticing that what I thought was tire tread vibration, is in fact only present when 4wd is engaged. I did a test by putting the tractor up on stands and testing for the vibration by running in 2wd and 4wd. The test confirms the source of the vibration is somewhere in the front wheel drivetrain.
I have also found the lost ujoint and have attached several pics of its condition when it was found. Note that there is a portion of the roll pin still in place.

So I have 2 questions:
1) How is it possible to shear off the roll pin without damaging the Ujoint splining.
2) What sort of damage also occurred to the front drive train during the ujoint event that has led to the vibration?

I would luv to hear your thoughts, suggestions and advice.
Brian

 

[3Lfarms]

It sounds like you may have installed the new u joint out of phase with the other end.
Did you ensure the joints are properly aligned?

 

[zzvyb6]

Easy to explain. The pin didn't shear in torsion, it sheared when the shaft decided to whip out. Vibration from an improperly installed/phased intermediate shaft most certainly is a likely villain here. The inner yokes must always be facing the same direction (in the same plane).

There may be an optional shaft available which has a rubberized flex joint isolator in it. Maybe the wrong shaft has been used as a replacement. The rubber coated isolators help very much to elliminate the vibrations. They also have poor durability.

 

[Ex Five 0]

The ujoint that was lost had been in place and un-tampered with since the purchase of the tractor 12 years ago. There was no vibration problem prior to the loss of the ujoint and subsequent replacement. I do know that I was totally unaware that the ujoints had to be properly phased when I replaced the lost one. I suspect, that when the rain stops up here and I can get a look under the machine, I will see that they are not phased correctly, which i will remedy promptly.

I still cant get my head around what sort of motion led to the original loss. I can see how any lateral whipping could take place since directly behind this ujoint, is a bearing collar bolted to the frame supporting the junction of the 2 piece front shaft.

 

[rScotty]

The ujoint that was lost had been in place and un-tampered with since the purchase of the tractor 12 years ago. There was no vibration problem prior to the loss of the ujoint and subsequent replacement. I do know that I was totally unaware that the ujoints had to be properly phased when I replaced the lost one. I suspect, that when the rain stops up here and I can get a look under the machine, I will see that they are not phased correctly, which i will remedy promptly.

I still cant get my head around what sort of motion led to the original loss. I can see how any lateral whipping could take place since directly behind this ujoint, is a bearing collar bolted to the frame supporting the junction of the 2 piece front shaft.

That bothers me too. I'd like to figure out what type of motion led to the pin shearing and the universal joint coming off in the first place. I doubt it is lateral motion, and would guess it is lengthwise motion of the drive shaft. Some sort of change in length....It is common for any drive shaft itself to have telescoping splines somewhere in its length, and I'm assuming that the BX has such a feature. Otherwise I'm not seeing how the U-joint could come off or a new one replaced. Telescoping motion that changes the length of the driveshaft could shear the pin and also make enough space for the U-joint to come off. Are there telescoping splines? And if so were those telescoping splines ever taken apart? Splined driveshafts are often be a source of phasing problems.

I think I need to look for some more pictures of the BX drive train.

 

[civilian]

I think I had a similar incident with my BX2230 that had probably over 1400 hours on it. I found the ujoint pieces. But I think I lost the roll pin, did not shear it. To fix it, I installed a new roll pin that was a bit larger in diameter. So did the OP 's pin start to back out and then the wobble of the shafts allowed the ujoint to disassemble? Just wondering. Jon

 

[Henro]

It sounds like you may have installed the new u joint out of phase with the other end.
Did you ensure the joints are properly aligned?

Same suggestion/possible (likely?) answer was made when the OP asked the identical question at the orange site.

He did not reply to that thread after asking the question...perhaps he will here?

 

[ruffdog]

The ujoint that was lost had been in place and un-tampered with since the purchase of the tractor 12 years ago. There was no vibration problem prior to the loss of the ujoint and subsequent replacement. I do know that I was totally unaware that the ujoints had to be properly phased when I replaced the lost one. I suspect, that when the rain stops up here and I can get a look under the machine, I will see that they are not phased correctly, which i will remedy promptly.

I still cant get my head around what sort of motion led to the original loss. I can see how any lateral whipping could take place since directly behind this ujoint, is a bearing collar bolted to the frame supporting the junction of the 2 piece front shaft.

Out of phase means it will try to speed up and slow up the front diff twice per revolution of the pto shaft. The speed/slow action gets worse the more angle the u-joints are.

 

[Ex Five 0]

I properly phased the two Ujoints and the vibration is gone. Thanks to all who responded to my post and pointed me in the right direction

 

[ruffdog]

I properly phased the two Ujoints and the vibration is gone. Thanks to all who responded to my post and pointed me in the right direction

:thumbsup: