Kioti RX6010 lug nut studs breaking

[Sean2202]

Hello all,

I have a Kioti RX6010 with a cab that has approx 1800 hrs. We use this machine on the golf course where I work. It is running Titan rear turf tire size 44x18-20. The rear tires are not filled with any ballast just air. After mowing on a very hot day this summer it was parked and the guys were on break when they heard a large ping noise. They came in the shop and showed me that one of the rear wheel studs had just broken off and landed a few feet away from the tractor. I assumed that it was a weak stud or the nut had been overtorqued. Looking in the records the tire had never been removed by us since we owned the machine.

A few weeks later I walked by the tractor as it had sat over the weekend and two more studs had broken off. Thinking at this time maybie the nuts loosened up putting stress on the studs. I checked all remaining nuts on both wheels and all were tight.

Has anyone else experienced this? The first one broke off with flush with the rim while the next two broke flush with the flange. Does anyone know what size the stud is with the thread pitch?

Thanks for any help

 

[Coyote machine]

Have you contacted your selling dealer? That's where I'd start. Possibly wheel nuts were over-torqued by factory, on at PDI by dealer gorilla?

 

[finn1]

The tractors are shipped to the dealer on skids, without the wheels being mounted. Likely the dealer over torqued the studs when he installed the wheels.

The dealer can order new factory studs if they aren’t in stock.

 

[Coyote machine]

Have you contacted your selling dealer? That's where I'd start. Possibly wheel nuts were over-torqued by factory, on at PDI by dealer gorilla? Were all broken studs on the same side or did both wheels have broken studs?

 

[Sean2202]

Yes my supervisor sent the selling dealer a messege this morning with the pictures above. I will let you know what they say. I would assume its out of warranty with approx 1800 hrs but does not hurt to ask. It was purchased new in 2014 by my workplace and we have all documented maintenance records since new.

 

[ritcheyvs]

The service manual says to check the wheel bolt torque every 50 hours. Wonder if that was ever done, and by whom?

 

[Threepoint]

The tractors are shipped to the dealer on skids, without the wheels being mounted. Likely the dealer over torqued the studs when he installed the wheels.
[snip]

This.

 

[ritcheyvs]

Based on the last photo and the fact you have 1800 hours on the machine, I think it is more likely the bolts were under-torqued/not re-torqued periodically.

 

[Kioti Paul]

I believe I would start by checking the torque on the remaining 5 studs (and the other side also). I doubt there will be any warranty, but at least (maybe) it will shed some light on what went wrong. Luckily, replacing studs is cheap and easy.

 

[finn1]

Based on the last photo and the fact you have 1800 hours on the machine, I think it is more likely the bolts were under-torqued/not re-torqued periodically.

I do agree that under torque is a possibility. My tablet doesn’t have enough resolution to determine if the coined surface at the nut interface is coined or shows signs of fretting from motion between the wheel and nut, which would support the under torqued theory.

Using a dial type torque wrench, one could check break away and pull to mark torque of the remaining nuts, on all four wheels.

 

[DLTTrekkers]

I would replace ALL of them bcz the rest is suspect aswell .

 

[Sean2202]

Just an update here. Since the first post I contacted the dealer and asked if he had seen this before. His answer "I see studs break all the time". I also asked him as I see in my owners manual there is a picture of this tractor with ag tires and it looks like there is 6 bolts and then two studs with nuts opposite each other. I inquired if mine should have that setup. His answer was "If it came with studs it should have studs. I see them listed both ways".
So while waiting for parts to come in I raised the rear of the tractor and put a jack stand under it and it hasn't moved. A few days later another stud broke off on its own in the same spot as the others. Now I only have 4 studs left on one wheel. Interestingly we were talking how strange it is only one side has been breaking then low and behold while the tractor is raised on jack stands on the bad side we noticed a stud from the opposite side had broken. Same location as the other studs.
We raised the tractor and put it on jack stands. Removed both tires. There is a 1 1/4 spacer between the rim and the hub. If this puts stress on the studs I do not know. Most studs broke flush with the hub flange. To remove the broken studs I threaded a nut as far as I could on the back side of the flange and welded the nut to the broken stud. I then heated the broken stud with a torch and removed the stud out the back side.
I cleaned up all the threads with a M18 X 1.5 tap while waiting on parts.

 

[Sean2202]

I just wanted to up date this thread. Kioti definitely changed this part along the way. Here is a couple pictures. The picture with studs shows the new stud on the top next to the old stud on the bottom. There is actually a slight difference in measurement between the two as measured with my calipers. The new stud is smaller than the old stud. While threading the new stud in it felt looser than the original stud until it was threaded almost all the way in. These were all factory Kioti studs (T4851-50300) $22 a piece. I replaced all the studs on both wheels then torqued them down in a multiple criss cross pattern increasing torque each time until I reached 210lb /ft as stated in the owners manual. All seems to be good so far.