Jason,
I've taken to using a shear pin (small bolt & nylon lock nut combo often for snowblower augers) instead of the spec'd part. It will protect your motor and hydro by breaking if necessary and the ones I get from the bins in box stores like HD, Lowes, Sears, TSC and the like have a smooth shoulder just long enough that or clears the Hub Assembly ( #2 on Mr. Atay's handy parts explosion).
I've taken to using a shear pin (small bolt & nylon lock nut combo often for snowblower augers) instead of the spec'd part. It will protect your motor and hydro by breaking if necessary and the ones I get from the bins in box stores like HD, Lowes, Sears, TSC and the like have a smooth shoulder just long enough that or clears the Hub Assembly ( #2 on Mr. Atay's handy parts explosion).