A little disappointed with Kubota

   / A little disappointed with Kubota #1  

crazyal

Super Member
Joined
Dec 12, 2003
Messages
7,753
Location
Northern Vermont
Tractor
Kubota, Case, Deere
Over all I've been very happy with my L4240 but one thing has been giving me problems. The bolts holding the rear wheels on are sliding back and forth. They are held on with 4 bolts and two studs. I think the size is M16-1.5x30. The whole in the center of the wheel, Kubota calls it a "dish", is too large. This allows the wheel to move slightly. The bolts only have lock washers on them, not that it matters as they aren't loosening up. But after 9 years the holes are starting to get oblong shape and now the metal is starting to wear down. This winter I finally had one of the bolts start to come loose so I was going to replace that disk but at $225 each I was only going to do it one at a time. I figured I would replace the bolts at the same time. While at the parts counter I put one of the bolts into the hole and was surprised that even the hole on the new disk has a lot of play so I didn't bother buying it only to have it wear down.

I'm thinking that maybe I'd be better off just drilling 6 new holes the correct size that will not have any play. I've also ordered some belleville washers to see if that will help put more pressure to keep the wheels from moving. The bolts flush with the backside of the axle so to use the washers I'll have to find longer bolts. Until now it was just annoying but with one bolt actually getting loose each time I use the tractor I can't risk the worst case, a wheel coming off. I made the mistake of going a little past the torque for the bolts and broke one of the studs (which is why I'm posting this). There's nothing on the inside the axle so I'm thinking of getting new bolts that are 20mm longer and put a nut on the inside to prevent the bolt from being able to actually fall out. Has anyone else had this issue? I'll take a picture later.
 
   / A little disappointed with Kubota
  • Thread Starter
#2  
This is from the better of the two wheels. This nut has never loosened up. The manual say 160 ft/pounds. Every time I've checked it with my torque wrench set at 160 it'll click without the nut tightening any further. I actually loosened one then torqued it back down just to be sure. The bolts are threaded all the way so it's not like they are bottoming out before applying the correct pressure to hold the wheel on.
lug nut.jpg
 
   / A little disappointed with Kubota #3  
Loose the bolt and then retight it.
 
   / A little disappointed with Kubota #4  
This is from the better of the two wheels. This nut has never loosened up. The manual say 160 ft/pounds. Every time I've checked it with my torque wrench set at 160 it'll click without the nut tightening any further. I actually loosened one then torqued it back down just to be sure. The bolts are threaded all the way so it's not like they are bottoming out before applying the correct pressure to hold the wheel on.
View attachment 590655

Your pic shows a stud with a flat nut and lock washer. Blowing up the pic to see the most detail possible, it appears the wheel hole is elongated and a tight seal of the wheel and nut/lock washer would be nearly impossible to achieve, IMHO. If this pic is an example of the best seal of one of the studs to the wheel(s), then you are faced with a difficult to achieve solution to securing your rear wheels both now and as time passes. Yes, you could put a nut and lock washer on the back of each longer bolt that could allow the bolt to stay in place instead of backing out.

I'm not clear about what you meant the effect of the wheel disks being too large is upon the wheels staying tight and not moving around. Do you mean that because the wheel disk that the wheel bolts to has a center portion that will not allow the wheel to fit flat and flush to the disk, and therefore the wheel can wobble and not bolt tight to the entire surface of the disk?

If so, this is likely the reason your wheel hole shown in you pic shows elongation and damage to the wheel hole perimeter that the lock washer and nut cannot overcome by proper torquing. Your wheels WILL, IMO, move because the forces are too great to keep the wheel properly positioned. If the interface of the mentioned pieces were designed properly the wheel disk would allow the wheel to sit tightly against it, and the wheel bolts would have thread followed by a tapered shaft section that would fit tightly into each wheel hole, and would bottom out against the wheel hole when torqued to spec, eliminating wheel shift on the disk and against the bolts, and studs, IMO.

So your cheapest 'fix' and see what the results will be approach, might take replacing each wheel bolt with longer ones and add a Nylock nut to the back of each one where it passes to the back of the disk.
Then check torque each week or similar to see if there are any further issues. Otherwise the best, though mos likely also most expensive fix would be to replace both wheels with new or used- if ones will no or minimal damage could be found, then add the above longer bolts/ Nyloc nuts etc. to keep the same thing from occurring. Hope this helps.
 
   / A little disappointed with Kubota #5  
My 2013 Kubota L3560 with R4/ag tires has factory inch standard Grade 8 bolts and nuts securing the rear wheels, not metric. There are no lock washers from the factory.

The ROPS is produced in Georgia with inch standard fittings, not Japan. The wheels may also be Georgia produced.

In my opinion, once the holes wallow oblong, no tightening will hold for long. The key is to keep the nuts tight when the wheels are new, until the nuts and bolts settle in. I was not successful keeping nuts tight with a socket set. Keeping nuts tight on replacement hubs required purchase of a battery powered impact driver.

The Kubota dealer routinely tightens rear wheel nuts with the rear of the tractor winched up, so there is no weight on the rear wheels during torque application. I presume the dealer zero weights the front, to tighten front nuts, using the Loader. The replacement hubs + inch bolts + inch nuts have remained tight. No lock washers. In this wheel application I would use fine thread bolts in preference to coarse thread bolts.

What worked for me, may or may not work for you.



If you decide to replace wheels, shop wheels and tires together as a unit. Kubota has what seems to me odd pricing on some wear parts. Wheels and tires together MAY be much cheaper than wheels and tires separately.

If you maintain KTAC insurance hub replacement would be covered.
 
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   / A little disappointed with Kubota #6  
Maybe you could fill the oblong hole with weld and use a debur to resize.
 
   / A little disappointed with Kubota #7  
Those are stud piloted not hub piloted wheels, a pia. Too late now to do anything as the wheels are pooched, you won't be able to keep them tight. Thinking out loud, wondering if you had used conventional wheel nuts, tapered seat which would have kept the wheel centered on the stud.
Lockwashers are crap IMHO, only time they come into play is if the nut comes loose that is if they don't break first. The Jinma that I had used them everywhere, I changed the bolts and nuts out to 10.9, used 10.9 flats and Loctite..............Mike
 
   / A little disappointed with Kubota #8  
I have a L4240 HSTC and never have seen this problem;I have R1's.Are yours R4's?I know the rims are different.
 
   / A little disappointed with Kubota #9  
This sounds like a dealer problem. If you bought this new then someone didnt bother to torque the wheel nuts when they assembled your machine at the dealership. The operators manual says to check wheel torque every 50 hours.
 
   / A little disappointed with Kubota #10  
Aren't there any tapered shim/ washer type spacers that could go on the stud, behind the wheel that would eliminate the play in the hole?
 
 
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