MX5400 hydraulic arm shaft and control rod damage

[DWilly]

New poster here. Howdy.

I was working with a rear blade on my new MX5400 and noticed the left side of the 3 point sagging. When I investigated, I found that the bracket holding the position control rod to the hydraulic arm shaft had become severely deformed, and in fact the control rod broke away, which allowed the left lift arm to slide completely off the hydraulic arm shaft.

A closer inspection found some of the teeth on both the hydraulic arm shaft and the lift arm were damaged. Overall, a small percentage of the tooth area is affected, but it's enough to prevent me from easily reassembling the arm.

I've attached a few pics.

On the lift arm photos, I'm showing them from opposite angles for clarity, but the damage seems to be limited to only one extreme end of the teeth. I would estimate maybe 5-10% of the length of each affected tooth, and perhaps 12 teeth total on the arm, and presumably a similar portion on the hydraulic arm shaft.

This is a pretty new tractor - just over 50 hours. I have a few questions for anyone who cares to respond.

1. Is this the type of damage that I should take to the dealership and shouldn't consider trying to repair myself? I have a neighbor who I'm confident could correct the teeth if they can be repaired. Filing down the deformed portions, I assume. But if there is potential damage to the hydraulic arm itself, or a need to disassemble it to make the repairs to the hydraulic arm shaft, I'm hesitant to go that route.

At a minimum I'll probably need to order a new control rod attachment bracket from the dealer.

2. Is this kind of damage potentially covered by warranty? Or would it only occur from what would be considered operator error or misuse?

3. Are there any other areas of potential damage, given what I've already found, that I should inspect?

Thanks in advance for any input.

 

[SDT]

I cannot see how that could have happened without serious abuse.

The only way you will know if Kubota will cover it under warranty is to take it to your dealer. It is certainly worth a try.

SDT

 

[MOOTS]

Holy hell. Following.

Edit to add, with such few hours, I would think this was improper assembly at the plant.
@DWilly what does the rear blade look like? If it were abuse, I’d say the blade would show damage too. But I don’t think it is abuse.

 

[TheOldHokie]

New poster here. Howdy.

I was working with a rear blade on my new MX5400 and noticed the left side of the 3 point sagging. When I investigated, I found that the bracket holding the position control rod to the hydraulic arm shaft had become severely deformed, and in fact the control rod broke away, which allowed the left lift arm to slide completely off the hydraulic arm shaft.

A closer inspection found some of the teeth on both the hydraulic arm shaft and the lift arm were damaged. Overall, a small percentage of the tooth area is affected, but it's enough to prevent me from easily reassembling the arm.

I've attached a few pics.

On the lift arm photos, I'm showing them from opposite angles for clarity, but the damage seems to be limited to only one extreme end of the teeth. I would estimate maybe 5-10% of the length of each affected tooth, and perhaps 12 teeth total on the arm, and presumably a similar portion on the hydraulic arm shaft.

This is a pretty new tractor - just over 50 hours. I have a few questions for anyone who cares to respond.

1. Is this the type of damage that I should take to the dealership and shouldn't consider trying to repair myself? I have a neighbor who I'm confident could correct the teeth if they can be repaired. Filing down the deformed portions, I assume. But if there is potential damage to the hydraulic arm itself, or a need to disassemble it to make the repairs to the hydraulic arm shaft, I'm hesitant to go that route.

At a minimum I'll probably need to order a new control rod attachment bracket from the dealer.

2. Is this kind of damage potentially covered by warranty? Or would it only occur from what would be considered operator error or misuse?

3. Are there any other areas of potential damage, given what I've already found, that I should inspect?

Thanks in advance for any input.

View attachment 74961
View attachment 74962
View attachment 74963
View attachment 74964

Yikes. I am having trouble visualizing what happened here. Did you by any chance back into something with a 3pt implement causing the 3pt to get pushed up beyond its normal travel?

At 50 hours it should be under warranty and if you have Kubota insurance it will pay for any damage caused by operator error. I would not reuse that rockshaft or lift arm.

Dan

 

[SDT]

Holy hell. Following.

Edit to add, with such few hours, I would think this was improper assembly at the plant.
@DWilly what does the rear blade look like? If it were abuse, I’d say the blade would show damage too. But I don’t think it is abuse.

Retainer bolts appear to be properly tightened yet something forced the upper lift arm off of the rock shaft.

Left side rock shaft bushing has moved left of design position. Bushing could have forced arm past retainer but don't know of anything internally that could cause that to happen. Who knows?

Were sway bars properly installed and adjusted?

Nothing to worry about if owner has KTAC.

SDT

 

[NCL4701]

Having a hard time visualizing a realistic scenario that would result in the substantial lateral force required for the pictured damage. Can’t think of anything in normal use that would create a lateral force on the upper lift arm at the rock shaft in light of the assembly being constructed to allow substantial lateral movement of the lower lift arm.

At 50 hours I’d at least have the dealer look at it for potential warranty and if that’s unsuccessful, Plan B would be insurance assuming you have KTAC or some other specific insurance on the tractor. Until those options are exhausted, I would not do anything to attempt repair as any potential payers are going to need to see it unmodified. Paying 100% out of pocket would be my last option.

I’d also put some thought into what I had done that could have potentially caused that to make sure whatever it was isn’t repeated.

 

[DWilly]

Thanks for your replies gentlemen. I believe the force that caused it may have been the back blade kick stand, which some idiot may have left in the extended position during use. I would love for someone to tell me such operator error wouldn't cause sufficient force for this to occur, but short of that, it might have to be chalked up to a learning experience.

 

[SDT]

Thanks for your replies gentlemen. I believe the force that caused it may have been the back blade kick stand, which some idiot may have left in the extended position during use. I would love for someone to tell me such operator error wouldn't cause sufficient force for this to occur, but short of that, it might have to be chalked up to a learning experience.

Insufficient information to answer that question.

SDT

 

[loggin]

New poster here. Howdy.

I was working with a rear blade on my new MX5400 and noticed the left side of the 3 point sagging. When I investigated, I found that the bracket holding the position control rod to the hydraulic arm shaft had become severely deformed, and in fact the control rod broke away, which allowed the left lift arm to slide completely off the hydraulic arm shaft.

A closer inspection found some of the teeth on both the hydraulic arm shaft and the lift arm were damaged. Overall, a small percentage of the tooth area is affected, but it's enough to prevent me from easily reassembling the arm.

I've attached a few pics.

On the lift arm photos, I'm showing them from opposite angles for clarity, but the damage seems to be limited to only one extreme end of the teeth. I would estimate maybe 5-10% of the length of each affected tooth, and perhaps 12 teeth total on the arm, and presumably a similar portion on the hydraulic arm shaft.

This is a pretty new tractor - just over 50 hours. I have a few questions for anyone who cares to respond.

1. Is this the type of damage that I should take to the dealership and shouldn't consider trying to repair myself? I have a neighbor who I'm confident could correct the teeth if they can be repaired. Filing down the deformed portions, I assume. But if there is potential damage to the hydraulic arm itself, or a need to disassemble it to make the repairs to the hydraulic arm shaft, I'm hesitant to go that route.

At a minimum I'll probably need to order a new control rod attachment bracket from the dealer.

2. Is this kind of damage potentially covered by warranty? Or would it only occur from what would be considered operator error or misuse?

3. Are there any other areas of potential damage, given what I've already found, that I should inspect?

Thanks in advance for any input.

View attachment 74961
View attachment 74962
View attachment 74963
View attachment 74964

Is it me or does something look wrong with the lift arm shaft..?? Seems to me that the teeth do not go in far enough to properly seat the lift arm. The teeth on the shaft look very short compared to the teeth on the lift arm. I have not personally had one of these apart but i would think the teeth have to be longer so that the arm can slide over further to fully engage the the length of the teeth on the arm.

Could be that I am not seeing things properly here...??

 

[North Idaho Wolfman]

I've never seen one do that, I would say it's got to be a defect of something

Is it me or does something look wrong with the lift arm shaft..?? Seems to me that the teeth do not go in far enough to properly seat the lift arm. The teeth on the shaft look very short compared to the teeth on the lift arm. I have not personally had one of these apart but i would think the teeth have to be longer so that the arm can slide over further to fully engage the the length of the teeth on the arm.

Could be that I am not seeing things properly here...??

The bushing is pushed out covering the rest of the spline length.

 

[DWilly]

Is it me or does something look wrong with the lift arm shaft..?? Seems to me that the teeth do not go in far enough to properly seat the lift arm. The teeth on the shaft look very short compared to the teeth on the lift arm. I have not personally had one of these apart but i would think the teeth have to be longer so that the arm can slide over further to fully engage the the length of the teeth on the arm.

Could be that I am not seeing things properly here...??

Good eye. Once a lift arm comes off, the shaft can slide toward the other side, which is what appears to have happened here. Here is a current pic of the shaft extending a bit beyond the right lift arm.

Dealer will pick it up tomorrow. Service dept is running about 4 days behind, so I’d guess I’ll know more Monday. I’ll provide updates just to help with the knowledge base here.

Service department said the left lift arm and the shaft, together, run about $400-$500. I would say “could be worse,” but I’m sure it will be.

 

[DWilly]

I've never seen one do that, I would say it's got to be a defect of something

That’s good to know. This can’t be the first time a kick stand was left down while working.

 

[rbargeron]

There should be a full-depth engagement of the splines in the arm, the nylon bushing and metal sleeve bushing should be further in, an o-ring seal between them. See attached part diagram.

The rockshaft moved right, withdrawing from the arm, bending the bolted 150 end plate. It became barely engaged on the splines - and finally failed while lifting the blade, with only the outer ends of the teeth engaged.

The question is what either pushed the left arm to the left or the right arm to the right ?

 

[SDT]

There should be a full-depth engagement of the splines in the arm, the nylon bushing and metal sleeve bushing should be further in, an o-ring seal between them. See attached part diagram.

The rockshaft moved right, withdrawing from the arm, bending the bolted end plate. It became barely engaged on the splines - and finally failed while lifting the blade, with only the outer ends of the teeth engaged.

The question is - what either pushed the left arm to the left or pushed the right arm to the right

View attachment 74981 -

Exactly why I asked about stabilizer bars.

SDT

 

[DWilly]

There should be a full-depth engagement of the splines in the arm, the nylon bushing and metal sleeve bushing should be further in, an o-ring seal between them. See attached part diagram.

The rockshaft moved right, withdrawing from the arm, bending the bolted end plate. It became barely engaged on the splines - and finally failed while lifting the blade, with only the outer ends of the teeth engaged.

The question is - what either pushed the left arm to the left or pushed the right arm to the right

View attachment 74981 -

I think you’ve summarized it perfectly.

When the damage occurred, I had the back blade adjusted so that it was swung out as far to the right as it can. It was also pivoted both to the left and right and tilted up and down on each side at various times while scraping pretty hard on very undulating terrain. And the kick stand was down. And I drove over a ditch few times, which is probably where the kick stand was damaged.

Overall pretty aggressive operating, but the only obvious (to me) mistake was the kick stand. I would think it would apply upward force, not lateral, but combined with the swing, angle and tilt of the blade and the ditch, I guess it was enough.

 

[DWilly]

Exactly why I asked about stabilizer bars.

SDT

It’s hard for me to say whether the stabilizer bars were properly adjusted. Not enough experience.

They were attached and didn’t show obvious malfunction (to my untrained eye) before or after the damage. I had a quick hitch on that the dealer originally attached. I hadn’t adjusted the stabilizers bars since delivery, and all 3 points of connection were solidly engaged when I finally removed the QH this morning.

 

[DWilly]

Did you by any chance back into something with a 3pt implement causing the 3pt to get pushed up beyond its normal travel?

Thanks for your reply, Dan.

Pretty sure I didn't back into anything, but it's possible, I suppose, that with the kick stand down and driving over a ditch could have forced the 3pt to move up beyond its normal travel.

 

[rbargeron]

SDT is on the money here. Properly-adjusted, the stabilizer bars should theoretically absorb side forces from a digging kickstand.

If it were mine, I'd use a small thin grinding wheel (Dremel?) to carefully clean up the damaged ends of the spline teeth until the arm will go back on the rockshaft. The splined connection has only lost a couple percent of its original strength - which when fully re-engaged will still be plenty strong. To reinstate the 3-point feedback function I'd replace part 150 with a new one TA150-37720, adding a thicker flat steel reinforcing bar with longer bolts.
There's a good chance you could fix it for 20 bucks instead of a thousand . Best luck, Dick B.

 

[SDT]

It’s hard for me to say whether the stabilizer bars were properly adjusted. Not enough experience.

They were attached and didn’t show obvious malfunction (to my untrained eye) before or after the damage. I had a quick hitch on that the dealer originally attached. I hadn’t adjusted the stabilizers bars since delivery, and all 3 points of connection were solidly engaged when I finally removed the QH this morning.

Quick hitch?

That's new information.

The quick hitch moves attached implements rearward a bit extending the lever arms attached to the tractor hitch, multiplying forces proportionally.

Yet another reason why I do not use quick hitches.

SDT

 

[SDT]

SDT is on the money here. Properly-adjusted, the stabilizer bars should theoretically absorb side forces from a digging kickstand.

If it were mine, I'd use a small thin grinding wheel (Dremel?) to carefully clean up the damaged ends of the spline teeth until the arm will go back on the rockshaft. The splined connection has only lost a couple percent of its original strength - which when fully re-engaged will still be plenty strong. To reinstate the 3-point feedback function I'd replace part 150 with a new one TA150-37720, adding a thicker flat steel reinforcing bar with longer bolts.
There's a good chance you could fix it for 20 bucks instead of a thousand . Best luck, Dick B.

I too would repair and reuse the damaged components unless Kubota decided to repair the damage under warranty, KTAC or otherwise.

SDT