B26 Broken Gear Teeth in Right Rear Differential Housing

[jallen4888]

This particular problem seems to show up in every instance as the right rear.
I've not heard of anyone having this issue with the left rear.

Had to replace right rear differential gears about 3 months (40-50 hours) ago and I'm broken down again. I'm not sure if my mechanic replaced the bearings also, or just the gears.

Does anyone know if this is a manufacturing defect that is causing the initial failure?

I do not use the differential lock, but I do keep the unit in 4wd.

Thanks in advance.

 

[CurtisC]

Mine is a 2009 with just under 650 hrs. and fortunately I have never had any drive train issues. Can't see how use of 4wd matters in this part of the drive train and you said you don't use diff lock (which still shouldn't matter unless you drove it in circles on pavement a lot with the lock on). A bad gear or gears should have been ruled out after the first replacement (unless you managed to luck into the same bad manufacturing run as the first set). Shaft alignment and/or play between RH shaft differential gear and main axle gear would seem to be a prime candidate. Short of bad machining of the right axle case, the main case, or the differential holder, that leaves the right side axle bearings and differential bearings. You mentioned you weren't sure if any bearings were replaced - I can't imagine the mechanic didn't inspect all of the right side drive train components carefully but it would be good to know specifically what was done besides replacing gears. You also didn't mention the age and total hours on your machine as to how quickly the first failure occurred in the tractor's life? If the machine had many good hours then two rapid failures, a bearing gone bad that wasn't replaced the first time sounds more likely.
As a B-26 owner I had never heard of this issue and that it favors the right side so please post any updates - thanks and good luck!

 

[North Idaho Wolfman]

It's not very common for any kubota to have the issues your having, so something has to be amiss

I would be changing all the associated bearings inner and outer, I would change both the bull gear and the gear shaft that drives it.

 

[jallen4888]

CurtisC My apologies for not mentioning the hours. It had approximately 1250 hours on it when the first issue happen, and now it's about 1300 hours. I ordered all new bearings and gears associated with the right rear. I'll be sure and post something after I get it up and running. Thanks

 

[Paybax]

Any update? My right rear just went today. 1
Month after warranty expiry. Happened while pushing a pile.

 

[whitetiger]

Any update? My right rear just went today. 1
Month after warranty expiry. Happened while pushing a pile.

Do you by any chance have liquid ballast in the rear tires?

 

[lugbolt]

yeah I did a b26, repeat failure almost identical a few years ago.

What I discovered on this one, and it was not immediate, was that the owner had shock loaded the transmission, which broke a tooth off. Once a tooth is broken off, the gear no longer meshes properly. Secondly, that piece of gear tooth (or whole tooth) will rattle around, and can/will damage other gear teeth, and in the case of the gentleman I'm speaking of, actually damaged the housing too. We discovered the broken gears and replaced them as normal, on the first repair. The second time, I went into the transmisison housing and found other metal debris, likely a cause of the second failure.

Look closely at your bearings, specifically axle bearings. They can sometimes fail, but won't leak. Not necessarily B26 specific but I've seen it on some of the other B series. Ball cage falls apart, piece jams parts, etc. On that note, you will want to look closely at everything to rule out a 3rd repair.

Shock loading these isn't a good idea. Shock loading meaning (in the case of the B26 I spoke of in the first part of this post), was due to the owner having the wheel turning and then it grabbed traction immediately. In his case, he had the outrigger down, wheel had no traction, then rather than letting off the pedal he just raised the outrigger and it went pop. Drove it back to the house and that's when the rest of it probably got beat up. Remember it's just a B series tractor, bigger than a lawn mower but not by much. They're not bulldozers. Just relaying what I was told by someone higher up....

 

[Henro]

Remember it's just a B series tractor, bigger than a lawn mower but not by much. They're not bulldozers. Just relaying what I was told by someone higher up....

Lugbolt, your excellent advise here is nothing but exceptional! Kudos for that!

BUT I have to ROFL about the comment I quoted above. ONLY because I remember you saying the same thing about the BX series.

I can say that my B2910 is quite a bit bigger than a lawn mower...and really there is no comparison.

I do get how things look different from the side where tractors are the 100 HP size...

Not meant to be a negative comment. Just an observation. Your help here on the forum is greatly appreciated.

 

[lugbolt]

Lugbolt, your excellent advise here is nothing but exceptional! Kudos for that!

BUT I have to ROFL about the comment I quoted above. ONLY because I remember you saying the same thing about the BX series.

I can say that my B2910 is quite a bit bigger than a lawn mower...and really there is no comparison.

I do get how things look different from the side where tractors are the 100 HP size...

Not meant to be a negative comment. Just an observation. Your help here on the forum is greatly appreciated.

yeah I get carried away sometimes. I made that comment just to reiterate that being rough on equipment WILL hurt it regardless of how well it's built. Having dealt with with a D9 at the landfill, and watching the guys use it, I came to the conclusion that it doesn't matter how big how heavy how expensive or how well it's built, someone's always gonna find a way. And it's not directed at the OP either, again, it's simply just what was relayed to me. And with that statement in mind, I don't baby anything I own, but I also don't abuse it, and I take care of it. Stuff costs too much to be careless. And, therein lies another issue, the definition of "abuse". Something I saw a lot of at the dealer was equipment would show up, particularly lawn mowers since 90% of what we did was lawn and garden stuff, people would get all bent out of shape because their stuff was broken. Then we'd bust our backside to fix it, and try to prevent it from happening again (if possible), then talk to the customer. A lot of times we'd get a statement something to the effect of "we know how hard we can push it now"...which tells me that they were doing something with it that it probably wasn't designed to do.

 

[mikester]

My adjustable wrench doesn't work well after I used it as a hammer. Damn crappy tools...

 

[GreensvilleJay]

so for 1200 hrs, fine, then poof, fix it, 40 hrs later, POOF..again...
as others have said ,replace BOTH bullgear AND pinion(the little gear).
While you're replacing all this stuff, 'relive the day' and figure out what YOU were doing.'Something' changed, in recent history. Maybe you added ballast? Were moving a heavy load and rammed into reverse?
Since you have a backhoe, you have a front bucket ?...did you ram into a pile of fill to load up,stopped real fast ? 'shock load' will do that kind of damage.
Not trying to be mean, but you need to figure out what 'operations' YOU were doing. It lasted 1200hrs( 6yrs ?) then TWO failures in close sucession.
It's unlikely a 'mfr defect', odds are great the gears came from different batches,maybe years apart.

 

[GeoHorn]

Lugbolts’ comparison to “bulldozer” is not far-off for what some owners expect from agricultural machinery. My M4700 has signs it was used for clearing land without regard to it’s original design.

When I bought it…it was clearly a low-time/stored indoor tractor …because the paint was bright, the upholstery on the seat great, and the tach hours <400.… but there were wooden twigs jammed between the tire bead and the wheel and the Frontwheel driveshaft cover was worn completely thru from inside by the rotating shaft because some operator must have driven the tractor over heavy brush and jammed the cover against the shaft. I discovered broken twigs/etc jammed up underneath the floorboards and the hydraulic filters were heavily dented and the toolbox ….(for some idiot reason Kubota placed the M4700 toolbox beneath the floor of the operator station)…. the toolbox was crushed and full of dirt.
The front axle tie-rod steel protector-guards were bent out-of-shape and the tie-rod covers badly torn from colliding with brush.

Apparently the previous owner thought he could use a tractor as a bulldozer, and I’m guessing the reason he sold it with such low hours is he discovered he needed a different tool for that kind of work.

Lugbolt is correct: Tractors are not bulldozers, screwdrivers are not chisels, wrenches are not hammers, and pocket-knives are not pry-bars. I keep telling my grandsons “Use the proper tool for the job.”

 

[GreensvilleJay]

re: screwdrivers are not chisels

yeah, sure, tell THAT to my wife..........

 

[UnhappyB26]

yeah I did a b26, repeat failure almost identical a few years ago.

What I discovered on this one, and it was not immediate, was that the owner had shock loaded the transmission, which broke a tooth off. Once a tooth is broken off, the gear no longer meshes properly. Secondly, that piece of gear tooth (or whole tooth) will rattle around, and can/will damage other gear teeth, and in the case of the gentleman I'm speaking of, actually damaged the housing too. We discovered the broken gears and replaced them as normal, on the first repair. The second time, I went into the transmisison housing and found other metal debris, likely a cause of the second failure.

Look closely at your bearings, specifically axle bearings. They can sometimes fail, but won't leak. Not necessarily B26 specific but I've seen it on some of the other B series. Ball cage falls apart, piece jams parts, etc. On that note, you will want to look closely at everything to rule out a 3rd repair.

Shock loading these isn't a good idea. Shock loading meaning (in the case of the B26 I spoke of in the first part of this post), was due to the owner having the wheel turning and then it grabbed traction immediately. In his case, he had the outrigger down, wheel had no traction, then rather than letting off the pedal he just raised the outrigger and it went pop. Drove it back to the house and that's when the rest of it probably got beat up. Remember it's just a B series tractor, bigger than a lawn mower but not by much. They're not bulldozers. Just relaying what I was told by someone higher up....

We have new information to show that the bolts holding the transmission were loose. The essential point is that the lever for engaging the differential lock has never been used or required for our work. I will post an updated video shortly.

 

[hagrid]

Probably doesnt help that the pinion is so small. The fact it's happening predominantly on the right is an outlier.

 

[GeoHorn]

re: screwdrivers are not chisels

yeah, sure, tell THAT to my wife..........

Yep… I had a Randall knife brought back from Vietnam and my Mom (rest her soul) managed to do to it what a year over there couldn’t… managed to put a chip in the blade trying to dig something out of a shower drain-grate.… when a common screwdriver would have removed the 2 screws holding the grate.

 

[DDIBON]

Having similar issue with my b26tbl, 400 hours.

 

[jallen4888]

OP here. Broke it again. lugbolt, I think you're correct regarding "shock loading". I've been using it for two years since the previous repair, but recently been working on uneven ground and today it popped again. I truly don't feel that I was abusing it at all, but I know I've managed to snag the bucket on a rock or a root while backing up, and had one wheel in the air, and then gained traction. These gear sets don't seem to tolerate a lot. I'm used to dealing with more robust equipment, and I'm beginning to get the picture that this backhoe is essentially made for moving gravel and digging water lines- not much more.

 

[hagrid]

Same side?

 

[jallen4888]

Same side?

Yep, same side. I was backing up after picking up some dirt, and it gave a very loud pop. This will be the 3rd time I've replaced these parts on the same side.