I believe that there is movement for and aft when the snowblower is in gear, and it is this forward pressure that causes the bolt to break. I don't know if you noticed, the coupling slides onto the shaft quite easily, and the bolt can't clamp the coupling to the shaft. The bolt only keeps it from moving forward. Today, I installed my BX2822 snowblower and looked at that coupling on the shaft. I believe that if a collar were added forward of the coupling, and locked tight to the shaft with a couple of Allen screws, that would keep the coupling from moving forward and shearing the bolt. I also don't understand why it doesn't specify to use a grade 8 bolt instead of a grade 5. In reality, it really isn't a shear situation since there is a key and keyway that keeps it located. In the spring I am contemplating having a collar machined to take up the space in front of the coupling. It will have a 1" I.D. and a 2" O.D. with 3 deep holes for the Allen screws. Put the Allen screw into its locked position, and then put another Allen screw on top of it to keep it from backing out or loosening.