Make sure you have the proper adapter kit. The backplate should be bored to match the prop shaft. There should be two adapter nuts...one of these adapter nuts has a hole with threads in the head of the nut (this is the jam nut) so that the Cone Retaining Screw can be tightened to the jam nut. Obviously the other adapter nut goes on first ...this is the Primary Nut. The Jam or "safety nut" nut screws into the Primary nut...then mount the spinner...and tighten the Cone Retaining Screw.

Backplate, Prop, Primary Nut, Jam Nut, Spinner...then Spinner Cone Retaining Screw.