BX24 diff lock disaster ... How many others have had this problem?

[check]

I hope you're not making turns while doing this because if you are, your BX might just end up like the OP's with a broken pin or worse. :confused2:

Yup. I do. No problems so far!

 

[ya472]

I have a 2010 BX25 and for some bizarre reason, the differential lock will engage, possibly with only one pin. ????

Since the axles have to be perfectly aligned to lock the differential, it seems the lock is engaged put the pedal won't go down at first then it does.

When I lift the rear tires off the ground and rattle them back and forth with the lock pedal in the ............

UPDATE: After talking to the local dealers, and being told that this is a new experience for them, I decided to tackle the project myself, and take the time to check all related engineering and maintenance issues. I have quite a bit of home experience as a mechanic.

I found what I consider the main problem with my BX25, and I assume the diff-lock is the same as BX24, etc.

The internal shift fork which rides on a shaft, jambs up because of Kubota engineering. I have posted my solutions in YouTube videos showing disassembly, damage, and my repairs and modifications.

WHEN this fork jambs up on its shaft, the differential pins will not dis-engage quickly. causing enormous stress when the pin is only 10% engaged and causes pin metal fatigue and breakage. This breakage is not caused by engagement, as that would chip the ends of the pins first and subsequent deformation.

There is a pin though the shift fork and through the shaft, and as the shaft rotates while pressing down on the pedal, engages the fork which pushes on a collar and engaging the pins into the spider gear. The soft shift fork metal deforms under pedal pressure at contact point with the pin and shaft. (not to be confused with the four pins engaging the spider gear) The fork deformation interferes with the shaft. It isn't easy to explain, see the video please.

I built a pedal stop to take the impact of pedal engagement, instead of the shift fork and also radiused the slot in the shift fork.

I also posted a video of my home-built HST fan shroud. This has dramatically increased airflow as well as protecting those fragile blades.

YouTube search: BX25 differential lock fail

 

[Zick]

UPDATE: After talking to the local dealers, and being told that this is a new experience for them, I decided to tackle the project myself, and take the time to check all related engineering and maintenance issues. I have quite a bit of home experience as a mechanic.

I found what I consider the main problem with my BX25, and I assume the diff-lock is the same as BX24, etc.

The internal shift fork which rides on a shaft, jambs up because of Kubota engineering. I have posted my solutions in YouTube videos showing disassembly, damage, and my repairs and modifications.

WHEN this fork jambs up on its shaft, the differential pins will not dis-engage quickly. causing enormous stress when the pin is only 10% engaged and causes pin metal fatigue and breakage. This breakage is not caused by engagement, as that would chip the ends of the pins first and subsequent deformation.

There is a pin though the shift fork and through the shaft, and as the shaft rotates while pressing down on the pedal, engages the fork which pushes on a collar and engaging the pins into the spider gear. The soft shift fork metal deforms under pedal pressure at contact point with the pin and shaft. (not to be confused with the four pins engaging the spider gear) The fork deformation interferes with the shaft. It isn't easy to explain, see the video please.

I built a pedal stop to take the impact of pedal engagement, instead of the shift fork and also radiused the slot in the shift fork.

I also posted a video of my home-built HST fan shroud. This has dramatically increased airflow as well as protecting those fragile blades.

YouTube search: BX25 differential lock fail

Got a link to your video?

 

[BX23S-1]

Got a link to your video?

Here you go, it wasn`t hard to find
Kubota BX25 differential lock fail - YouTube

You`ll have to go to his page to pull up all the videos where he`s working on the tractor... i posted a link to his page below.
ya472
- YouTube

 

[Rock Crawler]

Like a few of you all, I use the diff lock a good bit when digging. Also like many, I noted right away that you can not force the lock or immediately get the pin to drop in, you need to have the axle rotating while holding steady pressure (mild pressure, not foot stomping the thing) on the lever until things align and the pin smoothly drops in and the lever drops to the floor. I also will leave my foot on the lever while working the bucket into a bank to dig, I will back up and make turning adjustments and re-commit to the next dig approach all with the lock still in. I found that often it does take 3-5 feet of motion to get the pin to align, and I will often turn sharply to get the tires to travel different arcs while looking for the pin to engage. When I have gotten "stuck", I will release the HST input and stop the wheels, press the lever and slowly spin the tires while waiting for the pin to drop in and then add HST as needed to spin my way out.

While digging and locking as described above, when the dig is complete and the bucket is filled to my liking I will release the lever and use my heal to lift on the lever to force an unlock as backing from the dig, then I will do my sharp reverse turn and travel to the drop area. I drop the dirt, reverse spin and head back to the dig area where I will again get aligned to the dig area and get the pin to drop fully in before I begin the dig. While digging like this I am typically not limited by traction, I am limited by weak hydraulics and the wheels slipping in the tires. Since I have Rim Gaurd in the tires with 18 PSI of air, my tires do not grip the beads more so than the tread of the R4 tires grip on the ground. That is another subject... but if I am not locked the one wheel will spin in the tire and I have little to no digging force. At least with the lock I get 2 wheels spinning in the tires and get more forward force.

I try to be very aware of the diff lock and don't just drive around with it ever, I press and wait for the alignment to allow it to fall into place and I never do it at more than a crawling speed... be it while preparing for a dig or after I have inadvertently become stuck. I also always apply lifting force with my heal to ensure quick and complete unlocking, I do not like how the pin will at times release partially but yet remain locked, so I prevent this with my heal adding a bit of unlock assist force to allow me to feel the lever move upwards to the stop.

I would suggest that you consider also using your heal of your boot the feel for a complete and clean unlock, this should help prevent the pin from lifting partially and applying a concentrated shear force on the end of the lock pin that may slowly disengage without your assistance.

 

[BX23S-1]

Sounds like to me that the diff lock on these kubota`s are poorly engineered. Though i haven`t broke mine "yet", makes me wonder if it will break in the future. My other tractor in a similar class to my new BX23S has a diff lock, bought it brand new in 1989 (new model for 1990) has never had any issue with the diff lock, and i beat that machine since brand new day one, has never failed me, and i still run it year round today.

Now that i`ve read some comments about orange failures, maybe i should have bought the higher priced green tractor again instead of the orange tractor. My first kubota (1982) spent more time at the dealership for repairs to the front ring & pinion. Everytime i turned the steering wheel, it would snap the the pinion clean off. Eventually i got tired of the thing spending more time at the dealership than sitting at my home. I called the bank and told them i would be dropping off the keys to the tractor to them, it then became THEIR problem and not mine anymore. Hopefully i didn`t buy another problem child again. I`m up there in years, so i hope this orange painted/tainted brand out lives me...fingers crossed...lol. It came down to money when i bought the orange paint, thats the only reason i went with orange paint this time around, i live on a limited income, otherwise the paint would have been green again this time around.

I love the BX23S, but the quality worries me slightly after reading some of the problems & complaints with some of the orange brand.
I know i`ll be buried alive by the hardcore ORANGE fanboys in here for saying what i just said, but one thing i am not, is brand loyal.

 

[Rock Crawler]

PaPow, you should have priced the other orange :thumbsup:

I'm steering really hard towards a Kioti CK2610.

 

[sd455dan]

I'm sure you no longer need the pics... I am about done rebuilding mine and I have plenty. Got my fingers crossed that all is ok.

To anyone using a BX differential lock do so at your own peril. That lock is designed to fail. Total piece of garbage on a couple of levels.

We have three bx's in the family and i will be taking the angle grinder and cutting the pedal off on the two that haven't catastrophically exploded yet. Keep a watch on youtube for video and decide for yourself.

And to those that think the lock will engage without having the wheels turning you are wrong. The only thing saving Kubota on this is that there are a bunch of these machines out there that the owner doesn't even know what that pedal does and they never use it...

WOW
That is quite the locking design

checked out the vid where you can actually see the assembly and what 1st caught my eye was how badly ovalled the pin holes get in the side spider gear with use...

This design guaranties the side bearing surface of the spider gear will be raised at each pin hole with use

That in effect changes the gear clearance when not in lock mode, also will likely gouge the inside bearing surface of the differential carrier case. According to the video kubota only sells full sets of the 4 pinion gears...

Going to be looking into a small yard /barn tractor next year for the smaller stuff and it won't be a Kubota with this design of locker.

 

[BX23S-1]

PaPow, you should have priced the other orange :thumbsup:

I'm steering really hard towards a Kioti CK2610.

I hear that, but the one main thing that kept me away from Kioti in the first place was the fact that they are korean made. And now, here we are, i`m not liking what i`m seeing all over youtube with these kinds of (kubota) failures. I thought since the last kubota i bought (in 1982) was such a failure, i thought i would give them another try. Maybe i better dump it and buy something else BEFORE it breaks. I thought about the green paint again, but i cant see the extra dollars for it. But then again, had i bought green paint again, those extra GREEN dollars might have saved me an awful lot of aggravation again if this kubota breaks. I have a 30+yr old green tractor that has only had to have one ignition switch replaced, a starter relay by-pass, and nothing else. And due to my last (1982) kubota letting me down, thats how i ended up with the green tractor. Where`s the friggin quality anymore...sheeeeeez.

 

[Rock Crawler]

Where`s the friggin quality anymore...sheeeeeez.

Today, quality takes a back seat to a global market and bean counters who calculate failure rates and acceptable loss. They can make it with cheaper parts/materials, lower skilled labor and less quality control knowing that a percentage of customers will hardly use the equipment, another group will use it lightly, another will work it fairly but not over stress it, another will beat the heck out of it. Some will fail no matter what. Others will be factory freaks and go on forever. So they look at all of this and try to target a cost to build vs. cost to warranty median point where they can accept the loss of customers and revenue based on the calculated failure rate. Long term survival of the equipment (past the warranted period) is really not a part of the equation. So to your question.... quality went away in the mid 70's as the advancement of the global market took off and most things became a race to the cheapest way to make an item, the highest profit stream and acceptable losses. It is nearly gone. This is now a disposable world.