B2620 rear wheels not centering?

[SergioA]

Yes it is in the owners manual, but they do not do what the preach, as the pictures shows a taper, but there is no taper on these wheels! Its on the opposite side, inside and the wheels are non revesible.

 

[s219]

Yes it is in the owners manual, but they do not do what the preach, as the pictures shows a taper, but there is no taper on these wheels! Its on the opposite side, inside and the wheels are non revesible.

They have a picture/description for wheels with and without tapers (see below), so there must be two types of wheels in use for these tractors. All the ones I have seen use a lock washer, so the non-taper variety must be more common. I think they're doing exactly what they preach!

 

[SergioA]

I totally agree with you, but the thing is when they use the flat side of the nut and a lock nut, the axle hub has to sit on the center of the wheel perfectly, not 1/8" distance, as it can't center. They show a perfect fit on the picture, but in reality it doesn't sit. Have you had a chance to remove a nut on yours yet?

 

[Harry in Ky]

No doubt there's an issue there. Some "touched up" tapers on the boltholes doesn't seem like a solution. If the wheel center is anything but snug on the center of the axle flange, you rely totally on the taper of the nuts and boltholes to locate the wheel. Bad enough in one direction, but if you do much shuttle work, the back and forth action will accelorate the problem. Biggest issue I see here, once warranty is gone, it's on your dime.

 

[s219]

I totally agree with you, but the thing is when they use the flat side of the nut and a lock nut, the axle hub has to sit on the center of the wheel perfectly, not 1/8" distance, as it can't center. They show a perfect fit on the picture, but in reality it doesn't sit. Have you had a chance to remove a nut on yours yet?

There are shoulders stamped into the wheel around each nut/washer area, along with the raised lip of the center hole. If you look at my picture:

you can see that the washers are up against the raised lip of the center hole, and they nestle within the stamped shoulders. So that's how the wheel gets centered. When all the nuts/washers are snug down in their little spaces, the wheel would have to be evenly centered (within the tolerances of the wheel and lugs).

I think the problem in your case is that you did not have any washers, so there was no way for all the lugs to center the same way. In fact, if you refer back to your original picture:

you will see that the nuts are not evenly aligned. The flats of some nuts were facing the hub lip, while the points of other nuts were rubbing against the lip. Given the size of these nuts, that's easily going to push the wheel out of whack by 1/16-1/8" in any direction, which is evident in your picture -- the wheel is skewed away from the nuts with points touching the hub, and skewed towards nuts with the flats facing the hub. On top of that, the nuts were probably rubbing on the hub lip as they were torqued down. All of this would have caused the wheel to wander and walk around as it was tightened down.

I think the best solution would have been to add some washers -- even flat (non-lock) would do, as long as they were the right size. That would have gotten the nuts up away from the lip, helped evenly space everything about the rim/hub center, and then you'd keep the benefit of stronger mounting holes (ie, without machining tapers in).

I don't think Kubota has a great system here, but as designed and described in the manual, it should work as long as there are washers to center on the corresponding "sockets" stamped into the wheel. The best system would be one that is hub-centric (like most cars) where the wheel centers on the hub directly, and the lugs/nuts are only there to hold them together. Lug-centric wheels have been used on some cars, and are always a little wacky.

 

[beckmurph]

Well, I think the nuts are on backwards. My wheels do no have the lock washers on the nuts. The nuts are tapered and that is what would center your wheels. If you reverse the nuts and have the tapered side IN, that would center your wheels on the studs. :anyone:

 

[dennisgw]

I would agree as well unless the taper is such that it would bottom out before securely fastening the wheels. The instructions quoted earlier seemed to indicate that there were two types of rims. Could use 3 nuts with the taper towards the rim to center the wheel and then use the other three nuts flat to the rim with the appropriate washer to tightened AND then reverse the other three nuts and fasten with the flat side down again. The tapered nuts have to help center the wheel. Having two types is not a good design feature.

 

[s219]

Well, I think the nuts are on backwards. My wheels do no have the lock washers on the nuts. The nuts are tapered and that is what would center your wheels. If you reverse the nuts and have the tapered side IN, that would center your wheels on the studs. :anyone:

The 2320/2620/2920 owner's manual suggests there are two types of wheels in use, some with tapered seats, and others without. The same nut is used in both cases, but mounted in opposite directions. If you don't have washers and the tapers are pointing in, then you probably have wheels with tapered seats. SergioA's wheels did not have tapered seats, in fact he paid to have them machined in.

I forget the page number this is all described in the manual, but it's somewhere in the 30-50 range.

 

[s219]

I would agree as well unless the taper is such that it would bottom out before securely fastening the wheels. The instructions quoted earlier seemed to indicate that there were two types of rims. Could use 3 nuts with the taper towards the rim to center the wheel and then use the other three nuts flat to the rim with the appropriate washer to tightened AND then reverse the other three nuts and fasten with the flat side down again. The tapered nuts have to help center the wheel. Having two types is not a good design feature.

I really don't think that is needed -- once snugged down, the lock washers all center within depressions stamped into the wheels. It's not as precise as a tapered lug, but it's essentially doing the same thing.

 

[SergioA]

I understand what you are explaning S219, but this is not the best way to center a wheel.
I totally agree that once warranty is over your'e on your own!
I have included a picture of the insert sleeves I had made by a machinist to compensate for the gap in between the rim and the hub. Now with these sleeves and tapers done, these wheels can't go nowhere. It was the best solution possible, as Kubota did not want to admit there mistake or do anything about it.
Note, as per the machinist, there was enough steel to redo the tapers in the bolt holes, on the good side of the wheel.
Thanks guys for the good replies!

 

[SergioA]

S219, I was looking at you picture again, that would mean that you have special washers that fit perfectly on the stud, and are the exact size to sit on the lip of the rim?
Why would Kubota not done this the first time in my case, instead of installing the tapered nuts on the flat rim?
Just wondering....
I will try to get you a picture of my wheel with the sleeve installed.

 

[s219]

S219, I was looking at you picture again, that would mean that you have special washers that fit perfectly on the stud, and are the exact size to sit on the lip of the rim?
Why would Kubota not done this the first time in my case, instead of installing the tapered nuts on the flat rim?
Just wondering....
I will try to get you a picture of my wheel with the sleeve installed.

I think the dealer must have installed your lugs wrong to begin with. That's my only guess. I looked at probably 15-20 tractors at few dealers, and some used ones, when shopping for mine back in December, and they all had the lock washers with the nuts flipped to have the taper out and flat side in. I noticed it because at the time it seemed very odd to me and I had never seen that before. But after reading about it in the manual, it looks like it's the Kubota-recommended way to mount rims without tapered seats.

I don't think it's the best way to center the wheel, but it works well enough for a tractor, and Kubota probably knows some things we don't know about real-world experiences and issues with wheels and mounts. It would be great if someone at Kubota could educate us about why they do it this way.

I think those centering rings you made are the best solution, and that eliminates any question about the lugs providing alignment.

 

[SergioA]

Here's a few pictures with the centering rings installed. It may look offset on the picture, but it fits perfectly staight, it's the angle of the camera when I took the picture that makes it look that way.

 

[s219]

Here's a few pictures with the centering rings installed. It may look offset on the picture, but it fits perfectly staight, it's the angle of the camera when I took the picture that makes it look that way.

Looks good! :thumbsup: