Diagnosing and Preventing Steering Box Failure

In this post we are going to take a look at a very common service complaint that affects a wide variety of early Kubota B and L series tractors – steering box failure! In a follow up article, we will examine how to undertake a steering box repair and overhaul.

Symptoms of Steering Box Failure
The number one symptom of a failed steering box is that the steering will feel real loose and the front wheels of the tractor may wobble and oscillate. This is because the internals of the steering box are no longer integral and tight. Symptoms of steering box failure include:

  • wobbly steering
  • mushy, loose or unresponsive steering
  • raising the front of the tractor with a jack – grinding or resistance when turning wheels from lock-to-lock
  • shaking the steering wheel – feels really loose and ready to come right out of the tractor

If your Kubota B or L series tractor exhibits this type of wonky steering, do not ignore this repair! It is foolish and unsafe to operate your Kubota this way.

What Causes this Failure?
Typically, steering box failure is caused by 3 conditions, all working together to break your Kubota:

  1. Upper Steering Column Bushing Wears Out
    The failure of the steering box is most likely due to water making its way into the steering box through a defective, missing or worn bushing at the top of the steering column.

    This thick rubber bushing holds the steering shaft centered in the steering tube. When new, this bushing fits very tightly against both the steering shaft and the inside of the column tube. After several years of steering and turning your Kubota tractor, this bushing wears out and is no longer tightly holds the steering shaft.

  2. View of the top of the steering column - it is here that we should find a bushing (not shown).

    View of the top of the steering column - it is here that we should find a bushing (not shown).

    A view of two upper steering column bushings. Notice the worn out one one the left has lost its shape and is a bit oblong - a result of turning and steering a Kubota over many years.

    A view of two upper steering column bushings. Notice the worn out one one the left has lost its shape and is a bit oblong - a result of turning and steering a Kubota over many years.

  3. Rainwater
    Tractor is stored outside in the elements allowing rainwater to trickle down steering shaft. A few drips at a time, this rainwater will run down the steering shaft and toward the steering box.
  4. A Plugged Weep Hole
    Kubota did engineer a back-up fail safe into the steering box and column to prevent catastrophic failure and keep water our of it – a weep hole. Unfortunately, very few owners know of this back up weep hole system and as such do not service it.

    At the very bottom of the steering column, where the metal tube mates to the cast iron housing of the steering box, there is a small weep hole facing downwards. If you look closely at this picture you can see that the weep hole appears solid and plugged.

    At the bottom of the steering column is a weep hole that serves to let accumulated water out of the shaft. They typically get plugged with dirt and crud as shown here.

    At the bottom of the steering column is a weep hole that serves to let accumulated water out of the shaft. They typically get plugged with dirt and crud as shown here.

    The next step in the chain of events that leads to a broken steering box is that over a period of time, rainwater, dirt and debris make their way down the steering shaft and eventually plug the weep hole.

Weep Hole? A Big Deal?
You bet! The weep hole is located just above the lower steering column seal and bearing. This seal is a typical rubber friction seal that is spring tensioned. When the weep hole plugs, the entire steering column can fill with a head of water, dirt and junk. Since this moisture can no longer egress the column, the water will begin to move past the seal, right into the steering box – this is bad.

Since oil floats on water, the lower bearing that supports the steering shaft begins to go unlubricated causing severe wear. Once infiltrated with moisture and water, the bearings fail falling apart causing the steering shaft to wobble.

A shot of failed bearings freely rolling around the inside of the steering box - the source of wobbly unresponsive steering.

A shot of failed bearings freely rolling around the inside of the steering box - the source of wobbly unresponsive steering.

If the excessive wear on the steering shaft was not enough to destroy the steering box, then the first time the temperature goes below zero, the water in steering box freezes, causing expansion that fractures the box case – either out the bottom or it cracks the case on the sector shaft side.

A cracked steering box caused by rainwater getting into the box and then freezing, exploding the housing.

A cracked steering box caused by rainwater getting into the box and then freezing, exploding the housing.

Entirely Avoidable
It’s unfortunate when steering box failure occurs like this since that little hole can be easily cleaned out with a small drill bit rotated by hand.

I am also of the opinion that steering box failure is somewhat of a service secret at Kubota. You will not find a shred of info in any Kubota service literature, technical service bulletin or technical training manual that discusses  keeping that drain hole clear, yet Kubota sells replacement steering box shafts and bearings by the truckload!

Some tips to prevent this type of failure from occuring with your Kubota:

  • locate your Kubota’s steering system weep hole and get in the habit of clearing out the dirt and debris – a simple drill bit rotated by hand is enough
  • avoid parking your Kubota out in the rain which allows water to travel down the steering shaft toward the box
  • inspect and replace the upper steering column bushing if its worn out or oblong
Servicing the steering column weep hole is simple as rotating a drill bit by hand. We want to keep this area clean and free to let excess water pass.

Servicing the steering column weep hole is simple as rotating a drill bit by hand. We want to keep this area clean and free to let excess water pass.

Too Late. I’ve got a ruined Steering Box.
Okay, not to worry. If it looks like the steering box on your Kubota tractor requires an overhaul, or the box itself has a pressure crack due to freezing – stay tuned. In the next installment we will take a look at how to undertake a steering box repair job!

Service Department Vic

Related Articles
How to Repair a Steering Box – Part 1
How to Repair a Steering Box – Part 2

40 Comments »

  1. todd perdew Said,

    March 25, 2009 @ 3:22 pm

    Hey Vic, please hurry with the second installment, my steering just went out on my L225.

    Thanks

    Todd Perdew

  2. Mr. K Said,

    March 25, 2009 @ 3:37 pm

    Hey Todd – Vic already has that article underway. Look for it within the next couple of days.

  3. Vic Said,

    March 26, 2009 @ 8:21 pm

    Roger that! I’m on it!!

    Vic

  4. Thomas Morgan Said,

    April 7, 2009 @ 11:54 am

    Hi ! I am looking for a steering shaft and ball nut for an L260P Kubota mid to late 70′s year model. Any info on where to find these parts would be greatly appreciated!

  5. Vic Said,

    April 7, 2009 @ 9:13 pm

    Thomas, That’s going to be a tough one, as some of the parts have gone obsolete. I can source some of the parts, not all of them.

    Service Dept Vic

  6. FJC Said,

    May 12, 2009 @ 5:16 pm

    Hey, Vic! Looking forward to next installment. The steering on my ’85 B8200 is going/gone. Don’t want to move it until I can get the steering working properly.

  7. Vic Said,

    May 12, 2009 @ 9:08 pm

    Ya, I know! I have to get that article written! I’ve been so busy servicing equipment that it seems I can’t get my “homework” done! It’s “comming”, that’s all I’m saying and that’s what I’ve been telling my boss, Mr. K. So far he’s buying it!!

  8. BG Said,

    May 18, 2009 @ 12:14 pm

    Hi Vic! I’m pulling out the steering box on my L185 and was wondering if I have to completely disconnect the fuel tank and gauge cluster to remove it. Or, is it possible to just loosen up the tank and slide the steering box out without disconnecting it. What’s the best way to go about it? Thanks

  9. Vic Said,

    May 19, 2009 @ 10:03 pm

    It’s a little bit of a wiggle but it’s do-able. You do have to lift the box off the set pins, and then steer that contraption out of there.

  10. Ran Said,

    June 2, 2009 @ 2:55 pm

    evening Vic, my L175 steering just went out after all these years,Im taking it down now, when I get ur down I’ll be also looking for advise and parts to get her back to work…thanks…My breakdown questions were also about the tank ,its kinda tight.
    also does that stearing come out with out getting into the rest of the housing below.

  11. KENT Said,

    June 7, 2009 @ 12:23 pm

    STEERING JUST WENT OUT ON GREAT LITTLE ’83 MODEL…The screw gear just comes and out up when turned closckwise.

    KUBOTA Parts says the parts cant be had. I assume this is due to the Gray Tractor thing. Is the a cross ref part number or a better way to proceed.

    Thanks,

    Kent Buterbaugh, Jacksonville Fl.
    904-710-9650

  12. Vic Said,

    June 7, 2009 @ 4:31 pm

    Kent, What is the model of your Kubota, and is it a 2WD or 4WD? All parts are available to fix the box.

  13. ben Said,

    June 13, 2009 @ 11:33 am

    Vic,
    I need ball nut, balls and tubes for 73 l210? Where and how much? Thanks

  14. BG Said,

    June 15, 2009 @ 12:40 pm

    Hi Vic! Thanks for the info on taking out the steering box. The wiggle to free it from the gas tank wasn’t too bad. The sector shaft was completely missing the middle tooth when I pulled it apart. I tried ordering it but the dealer told me it was discontinued. Rest of the parts were available. Do you happen to know where I can find a sector shaft. The tractor is a 1979 L185 SN#10503. The sector shaft part number is 34150-16120. Thanks for all your help!

  15. Vic Said,

    June 15, 2009 @ 8:22 pm

    I’m thinking those are now an obsolete part!!! Yikes.

  16. Vic Said,

    June 16, 2009 @ 10:15 pm

    Your dealer isn’t digging deep enough! That’s a good part number, prices around $175USD, replaces part # 34150-16123

  17. BG Said,

    June 17, 2009 @ 1:16 pm

    Thanks Vic! I’ll have to beat the parts guy with the broken shaft till he gets me the right one.

  18. sun49dog Said,

    June 19, 2009 @ 3:23 pm

    Hi, Vic. I, too, have been told that the steering box for my (1985) B8200 is no longer available. I was given 2 part numbers for the whole assembly, depending on the tractor’s serial #. I don’t know which part goes with which serial #’s, but maybe someone here can answer that question. The first part # is 67810-41100, the second part # is 67800-41100. I don’t know what the difference is between these two assemblies or whether they’re interchangeable. I also don’t know whether either one is still available.
    I guess the next question is whether or not the individual parts of the box are available for an overhaul.
    Any help would be greatly appreciated.
    Thank you.

  19. Vic Said,

    June 19, 2009 @ 8:19 pm

    The complete steering box part # 67800-41100 fits Kubota B8200 tractors up to Serial Number 52926. Replacement steering box part #67810-41100 fits from Serial Number 52927 and up. There is a significant difference in price between these two boxes, with the early serial numbered B8200′s costing north of $1000USD. The individual parts for the overhaul of the box still come up on Messicks Kubota parts lookup. The problem getting the parts may be that someone doesn’t want to look them all up!

  20. sun49dog Said,

    June 22, 2009 @ 12:16 pm

    Hi, Vic.
    I rec’d the following email regarding the steering box on B8200 from another web site. I rec’d it in response to an order I placed for the whole steering ass’y.

    ***Start of message***
    “My parts manual says B8200D serial number 61722 would use the 67810-41100 steering assembly,
    The 67810-41100 is for serial number 52927 and above.
    We do not have 67810-41100 steering assembly and Kubota does not have it.

    The steering assembly part number 67800-41100 priced at $1021.55 is available.
    That is for Kubota B8200D serial number 52926 and below.

    The gearbox itself is the same part number on both steering gears.
    The ball nut assembly and tube are different part numbers.

    I would say either steering would bolt to the tractor.
    The difference would be the length of the steering shaft the steering wheel is attached to.

    I don’t have any technical drawing showing dimensions so that length is unknown to me.

    Below is the list of parts on the steering assembly for B8200D serial number 52927 and above.

    Note the gearbox, ball nut assembly ( part steering wheel is connected to) and side cover is no longer supplied.

    Current Part Num Quantity Desp Price Each Ext Price
    01123-50822 3 BOLT * 0.4 $1.20
    01517-51028 4 STUD 0.45 $1.80
    02116-50100 1 NUT 0.1 $0.10
    02172-50200 1 NUT 0.85 $0.85
    02174-50120 1 NUT 0.3 $0.30
    02176-50100 4 NUT 0.25 $1.00
    04512-60100 4 WASHER, SPRING * 0.1 $0.40
    04512-60120 1 WASHER, SPRING M12 0.1 $0.10
    04512-60200 1 WASHER, SPRING 0.15 $0.15
    04714-00100 2 GASKET 0.15 $0.30
    05411-00522 1 PIN, SPRING 0.3 $0.30
    06312-10020 1 PLUG 1.45 $1.45
    09500-26387 1 SEAL, OIL 2.75 $2.75
    31351-16063 1 WHEEL, ASSY STEERING 74.95 $74.95
    32130-16480 1 SCREW, ADJ. 5.15 $5.15
    34150-16440 1 COLLAR, ADJ. 1 2.8 $2.80
    34150-16450 1 COLLAR, ADJ. 2 2.8 $2.80
    34150-16460 1 COLLAR, ADJ. 3 3.45 $3.45
    34150-16470 1 COLLAR, ADJ. 4 2.8 $2.80
    34150-16480 1 COLLAR, ADJ. 5 2.8 $2.80
    35350-66820 1 RIVET 1.05 $1.05
    37300-16580 1 NUT, CAP* 6.7 $6.70
    38180-16110 1 GEAR CASE** * NLA NLA
    38180-16120 1 SECTOR SHAFT*** 203.8 $203.80
    38180-16410 1 SIDE COVER NLA NLA
    38180-16420 1 GASKET 3.1 $3.10
    38240-16320 1 O-RING 4.35 $4.35
    38240-16390 1 SEAL, OIL 11.8 $11.80
    38240-16490 1 SPRING 3.6 $3.60
    38240-16520 1 BUSHING 10.4 $10.40
    38240-16530 2 O-RING 2.2 $4.40
    38240-16630 1 NUT 6.85 $6.85
    38260-16210 2 BRG THRSTBALL18.5/38 10.4 $20.80
    66301-41150 1 COVER, SHAFT 17.85 $17.85
    67800-41410 1 ARM, PITMAN 52.56 $52.56
    67810-41100 1 STR. ASSY ?????? ?????
    67810-41120 1 TUBE, ASSY METAL 191.35 $191.35
    67810-41130 1 BALLNUT NLA NLA
    H6740-41420 1 CAP, STEERING WHEEL 9.5 $9.50
    ***End of message***
    My question is why would the length of the steering shaft & tube for the earlier serial #’s be any different from the later serial #’s?

    Also, are the cups that hold the ball bearings inside the ball nut (the tubes on the outside of the ball nut) supposed to have a split lengthwise or is that just a result of them having broken?

    Thank you for your help.

  21. Vic Said,

    June 22, 2009 @ 8:33 pm

    The earlier B82′s had the older flat styled black steering wheel, while the later versions used the newer “raised up” deep dish steering wheel in dark gray texture finish. I don’t have a spec on the shaft length either, but it seems logicl that the shaft would be different (shorter) on the newer serial numbered 82′s, since the steering wheel was dished and pulled up.

    The cups that hold the bearings in the ballnuts have a slot in them. It’s just the way the metal is folded to form that semi circular tube. The slit is not gapping though.

    l

  22. billy king Said,

    July 9, 2009 @ 12:44 pm

    where can i buy a gear box

  23. Vic Said,

    July 9, 2009 @ 8:36 pm

    It will be a used one, or a new old stock if you can locate one.

  24. Jenn Said,

    August 20, 2009 @ 6:02 am

    I am having no luck locating the ball nut assy for a B8200. Does any one have any resources to find a used, or old stock one?

  25. Vic Said,

    August 20, 2009 @ 6:32 pm

    Well that part number is still good, 67810-41130. Try Messicks. They advertise on our site. Fast shipping, great on-line communication.

  26. Jenn Said,

    August 21, 2009 @ 11:24 am

    Discontinued

  27. Vic Said,

    August 21, 2009 @ 7:50 pm

    I can supply an aftermarket ballnut that fits various Kubota, Yanmar and Iseki tractors with the NSK steering boxes, and I have a used ball nut from a B6200 that may work.

    The part number I supplied comes up as current Canadian available inventory. Don’t see why it’s listed as “disco” at Messicks.

  28. Sizzel Said,

    August 28, 2009 @ 10:10 am

    Kubota L225: How do you get those bearing races out of the bottom of the steering box?

  29. Vic Said,

    August 28, 2009 @ 10:15 am

    Kubota has a special puller for that bearing race, it looks like two very small hooks that can just catch under the lower edge of the race. It’s not a very large tool as it fits into the centre of the race!

    If you cannot find a tool to fit, and the race looks clean as most do, mount up some steel wool wrapped around a wooden dowel, and using a drill, clean up that race, insitu. As long as you don’t see pits, holes or nicks when you’re done, it’s possible to re-use that old race with the new bearing cup.

    Preferred would be to replace of course.

  30. Sizzel Said,

    August 28, 2009 @ 2:37 pm

    Vic,
    Thanks for the quick response. I’ve ordered bearings already since my races are rusty. I’ve ordered all the parts I need except the the steering sector shaft “34150-16120 replaced 34150-16123″ is unavailable. Any suggestions?
    Great website by the way,
    Thanks

  31. barnes chad Said,

    September 25, 2009 @ 3:42 pm

    i have a l245 dt(80) am i going to have the same problems as everyone above with finding the right parts….im getting worried

  32. TIM PRICE Said,

    October 14, 2009 @ 12:24 pm

    Hi Vic.
    I have a B7100HST with the steering completely gone out the local Kubota dealers say they can’t get the parts to repair (bearings, races, and seals). I’ve been able to come up with most of the parts, (bearings, races but no seals) also new upper shaft guide at steering wheel was obtained. I could not find any shims of any size to fit the box for adjustment purposes. The bottom race fits loose in the race holder in the box. How do I correct this and how many little bearings are inside of the worm gear housing, I think I found twenty and it appears there should be more. I tried to rebuild once and it lasted two (2) weeks and went out. the steering worm gear just spins the shaft and steering wheel with no effect on steering of the front tires. Need help !!! Tim

  33. b7100hst Said,

    October 21, 2009 @ 9:27 am

    OK, here is a story for you that will make you think! My low hour, mid 80′s B7100HST, had several of the steering failure warning signs that Vic identified but was STILL WORKING AND STEERING. What bothered me was the steering wheel/shaft would rise and fall as I turned the steering wheeel. I kept using the tractor until I could get a few free days to tear the steering apart (about 3 months). I tore my steering box apart yesterday and found alot of water in the box as the seal had failed, but get this, there was about 30-40 BEARINGS IN THE BOTTOM OF THE BOX!!!! In other words, someone had been replacing bearings but not taking out the old bearings or cleaning out the box. They had just replaced the whole shaft before I bought the tractor thinking it would fix the problem. There had to be bearings from at least three prior repairs! These bearings were obviously getting jammed at times in the shaft and in the workings based on the marks on the shaft. I’m luck the steering didn’t fail at a critical time or that my castings didn’t freeze and break. It is also a warning about who does your repair work. I ordered parts through the local Kubota dealer – total was $33, which I thought was reasonable as I am replacing every seal and bearing. This thread saved my castings at minimum, and kept me from experiencing steering failure, Thanks Vic!!!!!

  34. thecaptain Said,

    November 24, 2009 @ 9:43 am

    Hey Vic, any chance we’ll see the rebuild video follow up on the steering box for the L series? I’ve just rebuilt the steering box on my L175, new shaft, bearings, etc. however I have a significant amount of play or “free wheel” in the steering wheel before the tractor will begin to turn…. i.e turn the wheel about a half turn then the pitman arm begins to work and you can steer the tractor…. any thoughts about what is wrong? Thanks.

  35. Vic Byskal Said,

    November 24, 2009 @ 10:28 am

    Hey Cappy, Mr K is waiting for me to finish that, sorry for the delay! Pull that box apart again, you’ve dropped a few ball bearings during installation, or you’ve crushed the lower box bearing. When assembled there will be zero slack or “play” before the wheels move. Check the pitman arm and make sure it’s lined up to the score mark on the end of the steering sector shaft. Something has been missed or overlooked on your rebuild! Sorry :(

  36. thecaptain Said,

    November 24, 2009 @ 2:05 pm

    Vic, thanks for the quick response to my question. can you be a little more detailed on the sector shaft score mark is it easily found on the shaft? Also i didn’t explain before that when I begin turning the steering wheel it raises up a half inch out of the steering tube before it will begin to turn the wheels. Thanks again.

  37. Vic Said,

    November 24, 2009 @ 9:05 pm

    There is an alignment mark scribed on the end of the sector shaft, and a corresponding line stamped on the pitman arm. Take a close look and make sure they line up with each other. It “times” the pitman arm to the sector shaft rotation and ensures equal turning radius in both directions.

  38. scott Said,

    December 16, 2009 @ 2:11 pm

    Hey Vic,
    Is there anywhere to get the parts to completely rebuild my steering box? If I have it apart, I think that I may as well put as many new parts in it as possible. My tractor is a L-1500

  39. Waymon Said,

    December 24, 2009 @ 7:36 pm

    Vick, I want to tell I am very greayful for the help you offer to the Kubota tractor owners. You help a lot. I have old L1500 tractor. I bought this for my daddy. Al of his life he been a farmer at 83 years old farming is in his blood. My problem is the steering bax has been frozen and cracked on the bottom. A replacemment would be great but its hard to find these. The previos owner must let it freeze and bursted. The burst is in the bottom where the bearing race sets in. I thought about brazing it up and boring the housing out to fit the race. Do you have the proper numbers or parts numbers for the bearings and race. If you have a better
    way please inform me please. Thanks again for the videos. You are a great help.

    Waymon

  40. Service Dept Vic Said,

    December 25, 2009 @ 11:55 pm

    Yep. I’ve got those parts. Send me a PM and I’ll price the stuff out for you!

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