I have an old CB Associates spinner that I am trying to use on an O.S. .91fs an I am having a problem with it coming loose when I use a starter. The aluminum backplate slips on the engine drive washer and the mounting bolt comes loose from the aluminum prop adapter nut they use on those spinners. Any suggestions? One of the problems is the backplate is smooth where it touches the drive washer.
Thanks
Bob

could you need a new Prop Hub? or tighten the prop more? <try both'

Jim

Some folks cut a disc of sandpaper and place it between hub and spinner plate. In time, that trick often destroys the hub. I prefer to employ a disc of fairly hard leather instead. Actually
, thin multi ply wood can also work well especially with a good coat of varnish.

Another trick is a couple of roll pins to pin the spinner plate to the hub.

Glue two circles of of sandpaper back to back, punch a hole in it and use that as "washer" between propdriver and backplate. That'll keep it in place.

If you employ the old sandpaper trick; be sure to keep the prop tight. A bit of slippage can cause considerable wear to the hub knurling.I have inherited a few engines where some slippage had badly worn the drive face. Especially keep an eye on wood props.

Thanks for the suggestions everybody. I had forgotten about the sandpaper trick.
Bob

Hi!
I have solved that problem by fitting a 0,4mm plywood disk (the size of the diameter of the drive washer) between the spinner back plate and the drive washer.

Good choice, that wood disk holds well, more importantly will not damage the drive knurl.