Tiller shearing Drive Bolts

[Calbear55]

I have a B6000E with a Kubota Tiller. The Drive shaft on the tiller keeps shearing the two blots. I have tried Grade 5. Lasted for about 20 minutes. Will I have better luck with Grade 8? Is this a common problem with Kubota tiller? Should I just keep a bag full of 5/16 Bolts with me? Thank you ahead of time for any help or information.
Craig

 

[wushaw]

If you are gonna use the bolts then it is best for the bolts to sheer than your PTO system on the tractor.
A slip clutch is what is best used for tilling operations.
Tractor Supply Company - PTO Slip Clutch, 1-3/8 in. Smooth Shaft

 

[sal64]

i had same problem with my brush hog changed to allen head bolts and didnt shear as much .or drill out to 3/8.