Kubota Rear Inner Wheels Cracked

[vermontdane]

I have 2007 L3240HST which I always have a backhoe and front loader attached.
The dealer set up the tractor with fluid in rear tires and chains.

For the 2nd time, my rear inner wheels have developed cracks around the lug nuts towards the inner hub.
I check the torque often and always correct.
760 hours on the tractor.

A couple observations.
1. Kubota does not chamfer the sharp edges on the inner wheels. Sharp Edges are stress risers.
2. The wheel lugs are not self centering. The clearance on the bolts and studs will allow slippage.
One of the studs has sheared off. I have seen this on an M series tractor as well.

Are there others with this issue?

 

[WinterDeere]

Green wins again!

j/k... serious bummer. Would it appear that the stud failed first, and then the increased stresses on the remaining holes caused the cracking?

 

[vermontdane]

No, the right had failed before without damage to the studs.

Re "Green wins again", I lived in VT/NH area and talking to both the Kubota dealer and the JD dealers.
The JD dealer was a complete jerk acting like I was doing him a favor. Since both made in Japan, went with the Kubota.
I would appreciate no starking snips when replying in the future.

 

[Thomas]

I believe Kubota M 4800 had the same problem and some owners had 1/4" plate steel cut holes drill and weld to rim for fix.

 

[LouNY]

Any thoughts about welding up the cracks, chamfering the holes and getting some lug nuts with the tapered seats.

 

[vermontdane]

I am definitely chamfering all the sharp edges before installing the new inner hubs. With inflation, now $325 apiece.

 

[LD1]

Hard to tell in the pic but are you sure the steel is cracked? Looks like just paint to me.

IF it were mine, I'd plate and weld no big deal.

 

[Hay Dude]

Beginning to wonder if those kubota wheels (or others) were ever designed for the extra stresses put on them from being filled with fluids.
Try some cast rims or wheel weights if you can swing the cost.

I also experienced sheared lugs on previous Kubotas I owned.

 

[LD1]

Beginning to wonder if those kubota wheels (or others) were ever designed for the extra stresses put on them from being filled with fluids.
Try some cast rims or wheel weights if you can swing the cost.

Filled tires dont effect the stress on the rim beyond what added traction there is. And if they werent designed to be filled with fluid, they wouldnt come with two-piece air/liquid valve stems made for loading them.

 

[WinterDeere]

No, the right had failed before without damage to the studs.

Re "Green wins again", I lived in VT/NH area and talking to both the Kubota dealer and the JD dealers.
The JD dealer was a complete jerk acting like I was doing him a favor. Since both made in Japan, went with the Kubota.
I would appreciate no starking snips when replying in the future.

Sorry you're so sensitive, or didn't see my "j/k", as in "just kidding". Either way, it was a joke. I don't think Deere is better than Kubota, both are fine machines.

But since you brought it up, you are not correct about both being made in Japan. My Deere was made in Moline Illinois, according to the PIN tag and all accompanying paperwork. Not that anything is wrong with being made in Japan, my 1980's Deere was a Yanmar, and a great tractor that was still running fine at age 33 years when I sold it.

Back to your issue though... While chamfering may help reduce stress localization a little, doesn't this look like a materials issue? Wondering if the wrong steel was substituted in production (i.e. was this a machine built during pandemic supply issues?), or if work-hardening from stamping is just causing an unacceptable brittleness.