Prop nut torque for Tohatsu 30 hp 4 stroke

[ankonaman]

Changing out prop to S/S. Torque for nut in foot pounds?

 

[pvanv]

Assuming you have an MFS30B (EFI) motor.

Zero. It's splined, and retained by a brass castle nut. Clean and grease everything liberally (should re-grease annually); tighten the castle nut until the prop hub bottoms between the thrust bushing and the ss washer. Then back off slightly (ideally about 1/2 a flat of the nut) to allow insertion of the [new] ss cotter pin.

Remember that the ss prop will flex less than the aluminum prop, so you may need less pitch on the ss prop to achieve the same WOT RPM.

 

[ankonaman]

Thanks Paul.

 

[JustJason]

Zero. It's splined, and retained by a brass castle nut. Clean and grease everything liberally (should re-grease annually); tighten the castle nut until the prop hub bottoms between the thrust bushing and the ss washer. Then back off slightly (ideally about 1/2 a flat of the nut) to allow insertion of the [new] ss cotter pin.

Are you sure about that... there is in fact a torque spec in the Tohatsu factory service manual.... If you are tohatsu certified open the manual for this engine and flip to page 6-31.

 

[pvanv]

Yes, I am certain. Have done many, many Tohatsu splined props, of many vintages and sizes.

Even if you aren't a certified technician, how would you torque it, maintain that value, and still engage the cotter? Perhaps magic?

Prop nut torque was important when there were tapered prop shafts. That value was made irrelevant with the advent of splined shafts.