Check the front axle pivot

[armylifer]

One maintenance item that may need to be checked more often than the book recommends is the axle pivot nut torque. My manual recommends it be checked every 400 hours. I checked mine about 200 hours ago and it was good. Today I discovered it was loose.

The way I discovered mine was loose is the reason I am writing this warning. I was working on the tractor today when I suddenly heard a clank clank clank while I was driving. I stopped and checked underneath the tractor and discovered that the front propeller shaft fell off. The front U Joint coupling slipped off the front axle propeller shaft because the spring pin that holds the coupler to the propeller shaft sheared.

I believe that the reason the spring pin broke was because of excessive axle play due to the front axle pivot nut being too loose. Anyway, it was an easy fix but I thought that I would share the experience so you don't have to go through it.

In the picture: 1. Propeller shaft coupler 2. Spring pin

 

[RCW]

Joe -

At first I thought of the castle nut at the main axle.

The one you lost could really ruin your day, and cause some major tractor damage in some circumstances!

Thanks - good to know. Bet I'll be checking mine this spring.

 

[armylifer]

RCW - The castle nut that you refer to was loose and that is what caused the excess axle play that in turn caused the spring pin to shear. All is good and tight now but you can bet that I will be checking that nut more often than the 400 hours recommended in the manual.

I have been pondering why that nut was suddenly so loose after the being tight the first two times that I checked it. The only thing that I can come up with is that maybe there was some pressure on the pivot pin when I checked it the first couple of times and that gave me a false torque reading. This time I tightened the nut with the front axle off the ground. Anyway, it is an easy item to check and well worth doing during your maintenance schedule.

 

[SidecarFlip]

What I wonder with my M's and others is if the bushing that the axle pivot pin rides in is bronze or steel and if it wears over time. I keep mine well greased but I will check the nut next time I get under there to grease it. I'll make sure it's goot-n-tite. I have a lot of weight up there at times.

 

[tinkerwitheverything]

FWI I'm not sure if that pin sheared because of the front axle pivot nut being a little loose. What I'am thinking is that higher up under the tractor on that shaft is another u-joint yoke confingeration. This yoke slides back and forth on the splined shaft ahead of the steady bearing.If its rusted up and can't slide back and forth in this area this is more then likely what caused the pin to shear on the front yoke. I do take mine apart and grease that shaft and yoke just to keep it working freely and keep it from premature wear. If you jack the front of the tractor up and rock the front axle from stop to stop you'll see that the yoke does slide back and forth on the shaft up underneath the tractor just ahead of the steady bearing. Pretty sure thats what would have caused yours to shear.

 

[armylifer]

Since I had to completely remove the drive shaft to get the tractor home, I was able to check for any frozen or rusted slip joints. Nothing on the drive shaft was frozen up or rusted. This tractor is housed in the garage so there isn't any rust on it anywhere. I keep everything lubed properly anyway. My lube services are always done on schedule or before schedule.

 

[GeoHorn]

What I wonder with my M's and others is if the bushing that the axle pivot pin rides in is bronze or steel and if it wears over time. I keep mine well greased but I will check the nut next time I get under there to grease it. I'll make sure it's goot-n-tite. I have a lot of weight up there at times.

My circa 1996 M Service Manual suggests greasing that front axle support and shows a grease fitting...but there's no grease fitting on mine. Called the Kubota dealer and found early models didn't have the grease fitting provision. The curious thing is that there's no recommendation for the early non-zerk style to be greased at all. :{
I'm thinking of removing the front bracket and drilling/threading/installing a zerk fitting. (They want $75 for a new bracket with the zerk.)

 

[North Idaho Wolfman]

Armylifer,
I'm with tinkerwitheverything on this the front axle pivot bolt being loose will not cause the joint to shear the pin, it's the lack of slide in the joint behind it (in yellow)that will cause it to stress the front pins.

Lube the rear spline joint when you put it back together.

Also the front pins are not spring roll pins, they are simple pins with heads and a washer and cotter key that holds them in place.
Did you find the remnants of the pin in the shield when you took it off?

 

[armylifer]

Armylifer,
I'm with tinkerwitheverything on this the front axle pivot bolt being loose will not cause the joint to shear the pin, it's the lack of slide in the joint behind it (in yellow)that will cause it to stress the front pins.

Lube the rear spline joint when you put it back together.

Also the front pins are not spring roll pins, they are simple pins with heads and a washer and cotter key that holds them in place.
Did you find the remnants of the pin in the shield when you took it off?

I did find the remnants of the old pin. It is as you described but the WSM called it a spring pin so that is what i called it.

Also, I did check the rear U joint coupler ans checked for free play in the spline. All was good there and it moved back and forth freely as it should. I could not find any reason for that pin to shear except for the front to back movement from the front axle while turning. After tightening the axle pivot nut (castle nut) the front axle did not move forward and backward anymore.

 

[North Idaho Wolfman]

I did find the remnants of the old pin. It is as you described but the WSM called it a spring pin so that is what i called it.

Also, I did check the rear U joint coupler ans checked for free play in the spline. All was good there and it moved back and forth freely as it should. I could not find any reason for that pin to shear except for the front to back movement from the front axle while turning. After tightening the axle pivot nut (castle nut) the front axle did not move forward and backward anymore.

I agree 100% in checking and maintaining the proper bolt tightness!

And I'm not trying to bust your chops on the spring pin thing, I think older units used the spring pin that's why I wanted to point out the difference, there also looks to be 2 different pins depending on serial #.

 

[armylifer]

I agree 100% in checking and maintaining the proper bolt tightness!

And I'm not trying to bust your chops on the spring pin thing, I think older units used the spring pin that's why I wanted to point out the difference, there also looks to be 2 different pins depending on serial #.

I get it completely. If any of the information I give is wrong I expect to be called out on it. The terminology I used for the propeller shaft is what the book used. I would normally just say drive shaft, U joint, and slip joint, and so on but I used the terminology that the book used instead. Anyway, I sometimes find things different on my tractor than what is in the book. That sometimes makes life interesting.