Prop Nut Torque

[Boating_Al]

I was wondering what the torque spec would be on the prop nut on my 1994 Bravo II drive. and was is an average prop size for this drive. I currently have a 17.25 25P prop (Merc. 5.7), I think i may be over pitched.

Thanks

 

[Texasmark]

Re: Prop Nut Torque

My 90 hp Merc OB is speck'd at 55 ft lbs. Some of the guys on here say that the new plastic hubs from Merc need 100 ft-lbs. My local Merc dealer says he torques the new hubs to 90 ft lbs.
So I would say that your I/O should be somewhere around there. Why not ask your local marine dealer?

On your prop, if you can't get in the top of your recommended rpm operating range at WOT with your normal load then yes you have too much prop.

Mark

 

[Salmonseeker]

Re: Prop Nut Torque

I have a 2004 Johnson 50HP. The manual says to torque to 120 inch pounds. Not very tight in my opinion. I believe it is only 10 ft. lbs.

Jay

 

[Texasmark]

Re: Prop Nut Torque

I agree salmon on your 10 ft-lbs not being much. Course, when it's all said and done, years ago, when they OMC) had a shear pin there was no torque. the prop slid on the smooth shaft till the pin holes lined up, you slid in the pin with your fingers, slid on the cover, put a cotter pin in the cover to keep it intact and away you went. Those were said to be "slip hubs" or rubber cushioned hubs also.

Dunno :/

Mark

 

[Salmonseeker]

Re: Prop Nut Torque

My prop nut does use a cotter pin. So it really could not come loose. I usually just torque it to spec and them turn a little more until the hole for the cotter pin lines up. I wonder why merc torques them so high?

Jay

 

[walleyehed]

Re: Prop Nut Torque

OMC/BRP calls for 55ftlbs on 13 AND 15 spline.
Precision calls for the same....
I go to 50 and then tighten to the next closest location for pin or lock-tab.