What is causing my briggs and stratton lawnmower to keep shearing the flywheel key?

Answer by  Sparky101 (366)

This shearing problem could be caused by the blade coming into contact with an unmoveable object or by the key or keyway being worn out.

Answer by  shane35 (33)

The first thing that pops to my mind is that its in a bind. I would have the belts adjusted to decrease a bind.

Answer by  keepitsharp (48)

The shear key is there to protect the engine from breaking if the blade hits something that doesn't cut. Like a rock or a stump or something else that is hard. Make sue you don't replace the key with a key that is too soft otherwise it might shear when it normally shouldn't. Get a key from a mower shop.

Answer by  ferfer72 (2623)

The shaft that hooks the motor to the blade could be bent, which would be causing the blade to wobble, which would fatigue the sheer pin.