A little disappointed with Kubota

[Coyote machine]

I have read all of the posts to date. Would like to add my observations to the thread. FWIW, clarification of some terms being used. You have a rear wheel with an adjustable width inner rim, which has 6 total holes, two are for studs, four are for nuts and washers of a certain type. The wheel's have a large center hole, which allow it to be placed over a center axle hub, which has six holes that allows the studs and bolts to pass through to the back side of the axle hub.
When posters refer to replacing the disk, I suspect they are meaning the axle hub with pre-drilled holes, yes?

Here's my thoughts on the possible cause of the current issues. Assuming the bolts and nuts with lock washers are factory spec, the tractor likely was crated from Japan, did not have the wheels mounted yet, and possibly the selling dealer mounted the wheels to the tractor.
When being mounted possibly the tech who did so was not the dealer's top notch mechanic and may have while mounting each rear wheel placed one stud in each wheel to hold the wheel to the axle hub, then placed the rest of the studs and lug nuts/washers. Once in place if he started to torqued the studs and nuts, and the wheel did NOT seat totally flush to the axle hub flat area he did not notice , but kept torquing the wheel down to the hub, creating a poor quality fitment, which went undetected at the time of mounting the rear tires. Over time the wheel(s) shifted enough that the likely torqued down by air gun nuts and bolts could not keep the wheel from eventually fitting the axle hub as intended. Hard to say, but certainly a possibility, since nothing else to date explains the current damage to a certainty.

If it were my tractor, I'd remove each rear wheel, inspect the axle hub for damage and the inner rim of the wheel to see how the rim fits the existing axle hub, etc. If there are actual rim cracks in addition to the elongation of the rim's bolt/stud holes I'd replace that section, IF able to be purchased separate from the entire wheel/rim assembly. If not able to be purchased separately, then replace both entire wheel/rim assemblies, and all new bolts/washers and 2 studs/wheel. Other fixes are likely not going to make a once and done solution. However, Al may decide to try what he is hoping will work and could say him many $. I say go for it and see what the result is.I would add blue Locktite to the longer bolts, if you end up using them, where they go through the backside of the axle hub, where you are adding another nut, or use Nylock nuts there as available. If your plan fails then go for the above more expensive fix.
Hope this helps, good luck.

One other point of clarification: when Al and others speak of holes being elongated are you referring to the wheel holes in the rim or the axle hub holes, or both?

And for Fred, if all solutions fail do go to your local Kioti dealer and trade up!

 

[JWR]

Coyote: NO ! By disks we mean (at least I mean) the stamped steel wheel centers that accept bolts or studs through holes in them to the hubs. "Rims" mount to those "disks" by various arrangements, usually bolts through welded straps around the periphery of the rims.

I THINK std terminology is that 'rims' have rubber mounted to them and are then secondarily fastened/bolted to centers that I call disks and I think most do too. Rims do not bolt directly to hubs. Disks DO bolt directly to hubs.

You asked if "holes being elongated are you referring to the wheel holes in the rim or the axle hub holes, or both?"

I'm sure these guys are talking about elongated holes in the disks, NOT the hubs.

 

[ovrszd]

Coyote: NO ! By disks we mean (at least I mean) the stamped steel wheel centers that accept bolts or studs through holes in them to the hubs. "Rims" mount to those "disks" by various arrangements, usually bolts through welded straps around the periphery of the rims.

I THINK std terminology is that 'rims' have rubber mounted to them and are then secondarily fastened/bolted to centers that I call disks and I think most do too. Rims do not bolt directly to hubs. Disks DO bolt directly to hubs.

You asked if "holes being elongated are you referring to the wheel holes in the rim or the axle hub holes, or both?"

I'm sure these guys are talking about elongated holes in the disks, NOT the hubs.

Yep....

 

[SPYDERLK]

Coyote: NO ! By disks we mean (at least I mean) the stamped steel wheel centers that accept bolts or studs through holes in them to the hubs. "Rims" mount to those "disks" by various arrangements, usually bolts through welded straps around the periphery of the rims.

I THINK std terminology is that 'rims' have rubber mounted to them and are then secondarily fastened/bolted to centers that I call disks and I think most do too. Rims do not bolt directly to hubs. Disks DO bolt directly to hubs.

You asked if "holes being elongated are you referring to the wheel holes in the rim or the axle hub holes, or both?"

I'm sure these guys are talking about elongated holes in the disks, NOT the hubs.

Yes. Disk or dish.

 

[Coyote machine]

So, from axle hub to tire, we're at the axle hub, then the disk, (bolted to it), and last the tire on the 2nd rim piece, (holding the tire on the outermost rim, and bolted to the inner rim piece, correct?

Al's wheels are reversible to give him ability to spread or narrow tire width by changing the inner rim sections, yes?

So does anyone agree the possible cause of the damage could be as I posited?

Thanks,

CM

 

[aczlan]

No they don't. That's how rumors get started. I have a JD310 and it uses hardened bolts clamping hardened flat washers to hold the wheel to the hub. That's industry standard. You should check your sources.
rScotty

Sorry, I mixed up my tractors and whish bolt was which. It is a John Deere 6415 and they use bolts with lock washers to attach the inner dish to the outer part of the rim (we replaced the rims on the 6415 this summer as the tires were bald and the calcium chloride ate through the rims)

Both the 6415 and the 310 use flat washers under the lug bolts.

Aaron Z

 

[rScotty]

It is the clamping force of tight bolts that prevents all motion and wear. NOT the shape or size of the holes. As long as the clamped surfaces mate well and the clamping force is sufficient there will be no motion or wear. Even the very small clearance of snug holes would allow enough motion to wear out the assembly if clamping did not effectively "freeze" the joint.​

I agree with that, but apparently it is counter-intuitive. So far us us "flat washer + clamping force" guys are in the minority on this one.
Many posts in this thread offer different viewpoints. This thread has been educational for me.
rScotty

 

[ovrszd]

So, from axle hub to tire, we're at the axle hub, then the disk, (bolted to it), and last the tire on the 2nd rim piece, (holding the tire on the outermost rim, and bolted to the inner rim piece, correct?

Al's wheels are reversible to give him ability to spread or narrow tire width by changing the inner rim sections, yes?

So does anyone agree the possible cause of the damage could be as I posited?

Thanks,

CM

I don't.

 

[crazyal]

I agree with that, but apparently it is counter-intuitive. So far us us "flat washer + clamping force" guys are in the minority on this one.
Many posts in this thread offer different viewpoints. This thread has been educational for me.
rScotty

The problem is that the front wheels use a traditional lug nut to hold them in place. The rear wheels don't. Clearly Kubota assumed the clamping force would be enough to hold the disk (that's the name Kubota uses) from rotating. The bolts they use are fully threaded which makes them more likely to be damaged if the disk does rotate. My personal feeling is that Kubota for whatever reason decided only a lock washer was needed. For some reason my wheels needed more force to prevent them from moving than just a lock washer could provide. One of the best things about TBN is that you get lots of different opinions.

 

[crazyal]

So the lack of flat washers is the key. The other day I spent a couple hours snow blowing and today I did everything I could to put as much stress on the wheels as I could. Monday I removed the broken stud and put the belleville washers on both studs and 2 of the 4 bolts (the bolts are just barely long enough to catch all the threads in the axle so I wanted to have at least two still catching all the threads) on the bad wheel. I did things like skid a few trees and broke some trails that have been covered in snow (this puts lots of sideways stress on the wheels). I even did something I almost never do, I went down to an icy spot on the driveway and used 2wd to spin the rear tires so the chains could rip up the ice. It wears down the spikes on the chain and I'm not sure how good it is on the differential so I try to do it with it locked. After about 4 hours of use the bad wheel didn't move a bit and none of the bolts loosened up.

I got an email saying the bolts I ordered have been shipped so hopefully by next week I'll have them. I'm going to pick up some 5/8 grade 8 flat and lock washers and I'm going to do both wheels with both. The bolts are long enough so I can put nuts on the backside but I may not bother. Here's a picture of the good wheel from a little further away. The dark streaks are from water/ rust from where the center of te disk makes contact with the hub on the axle. Sometimes after snow blowing there's snow that will melt on the wheel. As it runs down it'll leave steaks like that. I'm assuming that the rust is from the paint being removed from the wheel moving over the years.