4wd issue - Drive Shaft connection to U-Joint

[captainluc]

Hi All,

I am new with my recent purchase of a B7200 HST-D a couple months back. While using my tractor in snow and getting stuck, I realized my 4wd wasn't working. I noticed the drive shaft was engaging by the transmission but it was not engaging at the front axle. I pulled off the cover protecting the u-joint, connecting the drive shaft to the front axle. I notice the drive shaft splines were making no connection with the U-joint. It seems like the U-joint has lost its threading and the drive shaft can spin freely without engaging the U-joint. I have attached a picture for your reference. I am not very technical and not sure how to fix this. Do I need a new U-joint?

I dread going to the dealer in the area as they seem reluctant to do any work on this machine since it is older.

Thanks in advance for any help or advise!

 

[85Hokie]

Hi All,

I am new with my recent purchase of a B7200 HST-D a couple months back. While using my tractor in snow and getting stuck, I realized my 4wd wasn't working. I noticed the drive shaft was engaging by the transmission but it was not engaging at the front axle. I pulled off the cover protecting the u-joint, connecting the drive shaft to the front axle. I notice the drive shaft splines were making no connection with the U-joint. It seems like the U-joint has lost its threading and the drive shaft can spin freely without engaging the U-joint. I have attached a picture for your reference. I am not very technical and not sure how to fix this. Do I need a new U-joint?

I dread going to the dealer in the area as they seem reluctant to do any work on this machine since it is older.

Thanks in advance for any help or advise!

Not to be making the situation worse....but I think you will need more than that!

Wolfman will be here shortly and throw you some diagrams better to explain what is needed. I look at the second picture, why is the housing all beat to hell? Looks like that shaft spun in an orbit and thus has come completely out of the yoke!

To me this exactly what would happen if a 4WD system is operated on a hard surface or with incorrect tire ratios. Are your tires stock sizes by chance?

 

[Tooljunkie]

It seems the splined male shaft has slid out of the female end(yoke).how i would approach this is to remove the two parts and closely inspect for damage and what caused them to slip apart. I belive there is a locating pin that works itself out and allows free movement of shaft.

 

[captainluc]

Not to be making the situation worse....but I think you will need more than that!

Wolfman will be here shortly and throw you some diagrams better to explain what is needed. I look at the second picture, why is the housing all beat to hell? Looks like that shaft spun in an orbit and thus has come completely out of the yoke!

To me this exactly what would happen if a 4WD system is operated on a hard surface or with incorrect tire ratios. Are your tires stock sizes by chance?

Not sure why the housing is all bent up to be honest. My only guess is they might have done it when I retrofitted a LA302 FEL onto the tractor.

The tires are stock with the original Ag tires and I believe I was moving mulch on a pact clay surface but not sure if that did it or was like that before.

 

[captainluc]

It seems the splined male shaft has slid out of the female end(yoke).how i would approach this is to remove the two parts and closely inspect for damage and what caused them to slip apart. I belive there is a locating pin that works itself out and allows free movement of shaft.

Thanks for your help. It also appears if there is not female threading left at all on the yoke. Could it simply be the whole inner ring to the yoke/one piece of the U-joint has broken apart from the rest.

Any idea on how to remove them or find the locating pin? I can't seem to find anything that can be dislodged to get this area apart. Again I am not very technical, sorry

 

[mickeyd]

Welcome to the forum from Alabama. Now is not the time to have problems but it always seem to work that way.

 

[Tooljunkie]

That damaged sheet metal cover needs to be unbolted and moved to get at u joint yoke mounting hardware.as well the rear end of driveshaft needs to come off, then damage can be asessed.

 

[North Idaho Wolfman]

Let dive in head first! OUCH!
Yep pull the cover to get to the goodies!
The reason the cover looks like that is from the drive shaft wobbling around beating the living crud out of it!

 

[captainluc]

Thanks you all so much for your help to this point, I would have never got this far otherwise.

I started to disassembly and focused on the front axle u-joint. I got the u-joint apart and was able to break up the assembly and slip off the cover. Once apart, the drive shaft and the splines look fine.

In my mind that left the two yokes of the u-joint to be the potential issue. When removed the one connecting to the front axle housing looked fine with all the female splines in order. I have posted of picture of the good yoke.

The other yoke which connects to the drive shaft seems to be the issue. It only has the female splines at the far bottom (about 2mm of threading). My guess is that is not enough for the drive shaft to connect to and move. Closer inspection of this yoke and it seems like the threading has some how sheared off and resulting in a very thin diameter still remaining. I have included two pictures for your reference.

My guess is I need to order a new yoke for that half of the u-joint? Your continued advise is appreciated. Thanks again!

 

[Tooljunkie]

Yes my friend,that is worn right out.or in mechanics lingo-its hooped. Not a real expensive repair.

 

[Bluegill]

Yep, fairly easy fix. Ya might want to run some counter weight on the 3 pt hitch
to take some weight off the front axle when the loader is on the tractor.

 

[Tooljunkie]

It would be difficult to determine the cause, lack of grease and 4wd on hard surface would be the two main causes. That being said, the tractor i used to care for eas always in 4wd, the operator was adamant that it needed to be in 4x any time it was working. I ,on the other hand only use it when necessary. The wear on that one is negligible. But it also carried a backhoe its entire life. Aka rear ballast.

 

[Bluegill]

Mine is in 4wd only when needed also. We had to rebuild the frontend on our
old L3750 from years of miss-use.

 

[captainluc]

Excellent points. I never thought about putting weights on the back to prevent this issue. Do you think a 5' box blade would be enough by itself? My guess it weighs about 150-200 lbs.

I do try and use 4wd only when needed but kept getting stuck in ruts when moving mulch so I ended doing most of the job in 4wd. I recall now that i was plowing into the pile very hard. I would drive into the pile until the tractor would stop moving, move the bucket and keep driving into the pile until it wouldn't move anymore to fill the bucket to max. My guess is that created too much pressure for this little machine.

 

[Bluegill]

Excellent points. I never thought about putting weights on the back to prevent this issue. Do you think a 5' box blade would be enough by itself? My guess it weighs about 150-200 lbs.

I do try and use 4wd only when needed but kept getting stuck in ruts when moving mulch so I ended doing most of the job in 4wd. I recall now that i was plowing into the pile very hard. I would drive into the pile until the tractor would stop moving, move the bucket and keep driving into the pile until it wouldn't move anymore to fill the bucket to max. My guess is that created too much pressure for this little machine.

You were getting stuck in 2wd because with the loader there was very little weight on the rear tires and more weight on the front. You want the larger rear axle carrying most of the weight & doing most of the work, otherwise the smaller front axle is going to eventually fail... Yes, the box blade will help, but I'd add another 100-200 lbs to it.

 

[North Idaho Wolfman]

I run mine in 4wd 24/7 but I don't have any hard ground to run on.

Looks like the bearings in the joint cross failed and it ate it's self up.

If the covers are worn or destroyed you will need to replace them as they are key to keeping things clean and running properly.
With a loader like that 500 to 1000#'s is about right.

I would also pull the whole driveshaft out and check the back parts completely too.