Vintage shear pins

[CATransplant]

Re: Vintage shear pins

CATransplant thanks for your diligence in tracking this down. I did think about going metric, just didn't consider going outside the states.

Rick - thanks for the tip on Mcmaster. I did a search with them before, but not metric, and there it was all this time.

Yesterday I tried a #8-32 screw cut to length just for testing the motor. Turns out it is a perfect fit, but was not brass. I measure .014" on the #8 and if I remember correctly 9/64 was .013". I did a search yesterday for #8-32 brass threaded rod and was able to order 1 24" piece for under $9 delivered. I realize I'm loosing a bit of strength with the threads, but I'd rather err on the side of caution.

Yeah, I thought about the numbered machine screw sizes, too, last night after I logged off. FR says that the originals were monel metal. I have no idea how the strength of monel compares to brass.

I'd save a search on ebay for Olson #2 shear pins. Eventually, someone will put some up there, and you can buy the real thing. Your solution will probably work OK, but if you look at a good hardware store, you can probably find those screws long enough to have a 15/16" unthreaded section or longer. That'd get rid of the threads.

There's always a solution, it seems.

 

[F_R]

Re: Vintage shear pins

I just spent the last couple of hours trying to find strength specifications / comparisons between Monel and Stainless Steel without success. But just from personal observation, they are somewhat similar. Monel is an alloy of nickel and copper and other trace metals. And tough stuff.

 

[CATransplant]

Re: Vintage shear pins

Yah, I looked too, and couldn't find a comparison. It sounds to me like SS would be a better choice for this thing. Fortunately, if he's using #8 machine screw stuff, those are available in SS as well.

 

[wilde1j]

Re: Vintage shear pins

try www.mcmaster.com item 88605K49. Rick

Bingo! BTW, SS and Monel are way too strong if you ever want the pin to shear.

 

[CATransplant]

Re: Vintage shear pins

Bingo! BTW, SS and Monel are way too strong if you ever want the pin to shear.

Apparently not, since the original shear pins for that outboard were Monel. Similarly, the drive pins for my old 1958 Johnson 35 were stainless steel. I did, indeed shear one when the prop hit a rock. No real damage to the prop, so it worked just fine.

I'm guessing that OMC, back when they designed that outboard, tested several different materials and found that Monel was just the right one. Over the years, they've used all sorts of different metals on shear pins for different motors, from aluminum and brass to stainless and Monel. A particular shear pin for a particular motor. I have no doubt they knew what they're doing, and an awful lot of old outboards are still around, spinning props with their original prop shaft.