2320 hydro drive shaft just snapped off !!!

[zzvyb6]

No, only 0 (or 180) degrees does the job. I'm describing the orientation of the inner yoke positions of the driveshaft. Just look under a truck to see what I'm referring to. Your standard PTO shaft ought to be aligned the same, too. Ever wonder why you can only put the two pieces together one way (both 'square' and triangular tube types) ? It's to preserve the shaft torque balance. The multi-spline joint in the OP's picture looks like it could go together in any one of 15 (or so) different ways. Usually these shafts are pinned to prevent them from being disassembled, thus potentially loosing their orientation. But who knows what could change that. I hope some owners look under their machines and tell us what they see. If the statistics of yoke angles are all over the place, then JD needs to recall the tractors.

In all of this, I'm presuming a double Cardan type jointed shaft. If not, then some other torque variation problem is a cause (like a failed motor mount). I just don't buy the grease theory. Nobody ever greases a truck driveshaft. There just isn't any movement unless a trans mount breaks (raises up the tailshaft) or a spring breaks (raises up the pinion nose). The failure mode is the same: unequal angles cause an unstable shaft torque vector.

 

[JDdude]

Autos do not use greasable u joints anymore..Sometimes less maintenance is best..Would a CV joint be better?

 

[zzvyb6]

And, it ought to add fuel to the fire when you see that early models had the solid, telescoping shaft (like OP's) which was replaced by a fixed length shaft with the traditional isolator. (see attached).

CV joints are only used when the shafts don't line up in the same plane. Like the driveshafts in a front drive car. The transmission is fixed position, but the spindle must steer as well as ride up and down. In a rear drive car with and independent rear suspension, the shafts don't steer. The rear gear shafts and the wheel spindle shafts are parallel all the time. Wheels go up and down but the shafts lie in parallel planes.

 

[diesel466]

No, only 0 (or 180) degrees does the job. I'm describing the orientation of the inner yoke positions of the driveshaft. Just look under a truck to see what I'm referring to. Your standard PTO shaft ought to be aligned the same, too. Ever wonder why you can only put the two pieces together one way (both 'square' and triangular tube types) ? It's to preserve the shaft torque balance. The multi-spline joint in the OP's picture looks like it could go together in any one of 15 (or so) different ways. Usually these shafts are pinned to prevent them from being disassembled, thus potentially loosing their orientation. But who knows what could change that. I hope some owners look under their machines and tell us what they see. If the statistics of yoke angles are all over the place, then JD needs to recall the tractors.

In all of this, I'm presuming a double Cardan type jointed shaft. If not, then some other torque variation problem is a cause (like a failed motor mount). I just don't buy the grease theory. Nobody ever greases a truck driveshaft. There just isn't any movement unless a trans mount breaks (raises up the tailshaft) or a spring breaks (raises up the pinion nose). The failure mode is the same: unequal angles cause an unstable shaft torque vector.

The spline on OP shaft is where it connects to transmission, that has nothing to do with phase of the shaft. And I grease my truck u-joints, I do not understand you statement that there is no movement. Everytime you take off the pinion wants to lift and as you go over bumps the axle is moving up and down and the driveshaft must slide in and out, Thats how all the trucks I have owned worked.

 

[Henri88]

Your Honor, it seems to me (as a Professional Engineer familiar with driveline mechanics and 20+ years in the field) that this driveshaft was misasembled. If the splined pieces are not aligned such that the phase angle of the input yoke and the output yoke was NOT ZERO, then a rocking moment existed in the driveshaft which eventually cause the cross retention pieces and bearings to fail. When the cross fell out of the bearing cups, it soon caused the shaft to be mechanically unstable and this resulted in catastrophic failure(s) down the line.
While I can't PROVE it beyond a reasonable doubt, it would be helpful for other owners to report back as to what the phase angles on their driveshafts are. If there are ANY which are non-zero, then these are likely going to have some pending failure with the worst one(s) being a shaft whose angles are 90 degrees in error. The failure is common to all machines from cars to trucks to any power take off driven machinery with this type of geometry.

It is possible that the shafts were misbuilt, that they were assembled incorrectly, or that this particular machine was serviced in a manner that required removal of one end of the driveshaft. If so and the shaft were reassembled incorrectlly, then this was a probable cause of the failure.

Am I missing something here. DIESEL466 is right. I thought the drive shaft was a one piece shaft. Unless it was miss-built, the yoke can't not be off phase. It would be impossible to have it assemble incorrectly. The spline are situated at the end of the u-joint and slides in the output shaft of the tranny.

 

[KubotainNH]

Unless it was miss-built, the yoke can't not be off phase. It would be impossible to have it assemble incorrectly. The spline are situated at the end of the u-joint and slides in the output shaft of the tranny.

Zzvyb6 has an interesting hypothesis. He's saying it may have been miss-built. The lower shaft in the picture he posts shows what looks to be 2 shafts that presumably attach via splines. If it is not keyed and it was put together off by a few splines then the joints on each end will not line up. I can see that making a mess of things but without seeing a picture of the whole shaft all we can do is speculate. If I was the op I sure would make sure it's built correctly when it comes back and always monitor it.

 

[beppington]

Zzvyb6 has an interesting hypothesis. He's saying it may have been miss-built. The lower shaft in the picture he posts shows what looks to be 2 shafts that presumably attach via splines. If it is not keyed and it was put together off by a few splines then the joints on each end will not line up. I can see that making a mess of things but without seeing a picture of the whole shaft all we can do is speculate. If I was the op I sure would make sure it's built correctly when it comes back and always monitor it.

Whereas I think I would sell it!

Not to be a negative gus, but I wouldn't want that "issue" playing on my mind every time I used my tractor.

 

[Henri88]

Zzvyb6 has an interesting hypothesis. He's saying it may have been miss-built. The lower shaft in the picture he posts shows what looks to be 2 shafts that presumably attach via splines. If it is not keyed and it was put together off by a few splines then the joints on each end will not line up. I can see that making a mess of things but without seeing a picture of the whole shaft all we can do is speculate. If I was the op I sure would make sure it's built correctly when it comes back and always monitor it.

If you compare the op and Zzvyb6 pictures, it seems to me that the op have the early model. ''fix shaft''.

 

[KubotainNH]

If you compare the op and Zzvyb6 pictures, it seems to me that the op have the early model. ''fix shaft''.

I looked at the pictures, I didn't see enough of the shaft to make that distinction. Maybe I missed one or didn't look close enough but there appears to be other parts in the way to see it all easily. BTW, the shaft you see in this picture is not the one with the issue, it is above it. http://www.tractorbynet.com/forums/...0-hydro-drive-shaft-just-img_1840_smaller.jpg

Beppington, I think the op mentioned dumping it. Now he can say it has a new drive shaft

 

[Henri88]

I looked at the pictures, I didn't see enough of the shaft to make that distinction. Maybe I missed one or didn't look close enough but there appears to be other parts in the way to see it all easily. BTW, the shaft you see in this picture is not the one with the issue, it is above it. http://www.tractorbynet.com/forums/...0-hydro-drive-shaft-just-img_1840_smaller.jpg

Beppington, I think the op mentioned dumping it. Now he can say it has a new drive shaft

If you look at the yoke with the spline, you can see that the older model is a split yoke at the spline with a lock bolt, while the new model is a all around one piece spline with no locking bolt just like his, it seams. Also if you compare the welding of the yoke to the shaft of the op picture with the picture of the 2 shaft, it gives us some indication that it might be the fix shaft on his tractor. Of course, all of this would have to be confirm by the op. :confused2:

http://www.tractorbynet.com/forums/...0-hydro-drive-shaft-just-img_1838_smaller.jpg

http://www.tractorbynet.com/forums/...0-hydro-drive-shaft-just-img_1839_smaller.jpg

http://www.tractorbynet.com/forums/...320-hydro-drive-shaft-just-2320-driveline.jpg