1988 Force 125 prop nut?

[ahickman]

When taking the prop off to adjust the timing/idle in a barrell last week, I quickly noticed that the previous owner had used a brass nut to hold the steel prop on. This nut when removed, crumbled in terms of the inner threads. A few questions for anyone regarding the prop nut and shaft:

1. Is the nut supposed to be brass or other softer metals?
2. Many years ago when I had smaller motors (Evinrude 25 HP, etc.), the prop shaft had a shear pin which would allow the propeller to spin freely if run aground or similar damage. This engine has nothing to relieve the prop in such a way. Is this correct?

Thanks,

Aaron

 

[HighTrim]

Re: 1988 Force 125 prop nut?

The prop will have a hub inside it to take the imact.

 

[Frank Acampora]

Re: 1988 Force 125 prop nut?

Nuts: You have the option of using either. Earlier Force engine used a stainless nylock nut. Later Force engines made by Merc. went back to bronze nuts. The nice thing about bronze is that it will not gall and cold weld to the threads. Much easier and cheaper to replace a corroded/stripped bronze nut than to cut off a stainless one and possibly ruin the shaft. The prop nut is always bronze, not brass because brass dissociates the copper and zinc, and corrodes in salt water.

Props are splined to the shaft and the rubber insert supposedly absorbs shock. I can't think of any large engines that still use a shear pin or thrust pin.

 

[ahickman]

Re: 1988 Force 125 prop nut?

Thanks. The replacement nut then can be stainless or other and not brass?

 

[ahickman]

Re: 1988 Force 125 prop nut?

Sorry Frank, your reply came before I posted the above response. You answered my questions well enough. Just curious about the torque ft/lbs needed to tighten it down.