Loader "pivot" bolts

hunt4570 · Oct 15, 2015

Ok, Kubota 3540W LA724 loader, owned it about 6 months. 450 hrs

Look at the pics cause my terminology is most likely wrong

. You will see the pivot pin working its way out of the hole, this is the second time I've had to replace the bolt holding it in. Granted I replaced it with probably a grade 2 bolt I had in the garage, now my question..

Should I replace it with a grade 2 (shear bolt) or go with a grade 8? Do I really need it to shear at this spot? I'm thinking not. Also... is there some underlying problem going on here I need to attend to? I'm the second owner of this tractor and it only has about 450 hrs on it

And yes I grease those.

Thanks.

SPYDERLK · Oct 15, 2015

Go to grade 5 and be sure the shank goes completely thru both shear points so only the shank sees shear stress. You do not need shear protection here but you certainly dont want bolt failure. Use the largest dia for the hole. Keep up the greasing.

Valbird · Oct 15, 2015

Consider pulling the pin and looking in the cylinder attachment bore, and see if there is anything not smooth, or which would otherwise contribute to a rotational shear force on that pin.

Barring that, I would look at the Kubota part and determine the bolt grade.

LD1 · Oct 15, 2015

ITs not a shear bolt, rather a bolt to keep the pin in place AND keep if from rotating in the bucket frame where it isnt greased. ITs greased in the loader frame and thats where you want it to spin.

The underlying problem is lack of grease. IF it spins freely, you wont break that bolt.

Leejohn · Oct 15, 2015

You said you grease it, but is the pin getting the grease? By the picture it looks like it is not, pull pin clean the holes out and put a new grease fitting in.

Leejohn · Oct 15, 2015

Looks like we jump on that at the same time.

crashz · Oct 15, 2015

Looks like you replaced a few of the retaining bolts with longer ones. Could the bolt and nut have sheared off at the boom stops? Seems like that could have caught it if the long end was down.

hunt4570 · Oct 15, 2015

The longer bolts were there when I bought it.

I grease through the zert and stop when grease comes out one side, so I'm sure its getting grease.

Think I'll go through and replace all these bolts.

Valbird · Oct 15, 2015

hunt4570 said:
The longer bolts were there when I bought it.

I grease through the zert and stop when grease comes out one side, so I'm sure its getting grease.

Think I'll go through and replace all these bolts.

That is not always the case. I have seen a dam of polymerized grease and dirt stop the flow of grease in a plain bearing. That is why I suggested pulling the pin and looking at the end on the cylinder.

While you are there, you can clean it out with a power washer or rags and solvent. Get it real clean, and make sure the wear pattern looks normal and the surfaces smooth. Then oil it up, reassemble and grease it.

That is at least how I would approach a problem similar as to what you describe.

k0ua · Oct 15, 2015

The question I would have is what happened to the bolt? Did it just fall out? All it has to do is just keep the pin in. There should not have to be much force on it. The original had a type if lock nut with plastic in the top of the nut to help prevent loss of the nut from vibration and hence loss of the bolt. The nut is not normally tightened down, and the bolt is free to move up and down in the hole. But is retained by the locknut. As others have noted, the pin does not appear greasy. It should be.