"Drive" pin vs. "Shear" pin

kfa4303 · Aug 12, 2011

HI all. Just wondering what if any difference there is in a "drive" pin vs. a "shear" pin. Are they, in fact, the same thing that go by different names? Are drive pins consumable (designed to fail upon impact) like shear pins, or are they more rigid? The "drive" pin in my 20hp looks like it may be made of SS, whereas the "shear" pin in my 10hp is clearly brass. If drive pins are not consumable what is designed to fail in the LU in the event of an impact? The prop hub? If "drive" pins are consumable, I want/need to get some spares for my '66 20hp, but I'm not sure of the size. I've heard folks get brass rods at the hardware store and cut pins to length themselves, but I'm not sure of the type or size of brass rod I'd need to get. Thanks for any tips.

jspansel · Aug 12, 2011

Re: "Drive" pin vs. "Shear" pin

I know on my 5 hp merc, the cotter pin is just to keep the prop nut from backing out. Pretty sure the hub will give. I could be completely wrong though

But its on a spline, so it would have to be the prop that gives...?

iwombat · Aug 12, 2011

Re: "Drive" pin vs. "Shear" pin

A drive pin is stainless and is used with hubbed props. It's not supposed to break even if the prop hits something.

A shear pin is bronze and is used with the older non-hubbed props. It's supposed to break when the prop hits something.

The terms are often used interchangeably, but they're two different animals.

nwcove · Aug 12, 2011

Re: "Drive" pin vs. "Shear" pin

for getting the correct size brass rod to make your own shear pins, just get your drill bit set out, find the one that fits the hole in the shaft correctly, and go with it.

boobie · Aug 12, 2011

Re: "Drive" pin vs. "Shear" pin

On the old mtrs I'd use nothing but brass. It's a lot cheaper than, d/s's, gears and props. May be a little work to change but well worth it $$$$ wise.

kfa4303 · Aug 12, 2011

Re: "Drive" pin vs. "Shear" pin

I see iwombat. So you either have a hubbed prop with a SS drive pin or an unhubbed prop with a bronze shear pin, is that right? Boobie, are you suggesting I replace all drive and or shear pins with bronze pins just to be safe? Thanks again.

royal0014 · Aug 13, 2011

Re: "Drive" pin vs. "Shear" pin

'Drive' pins and 'shear' pins have different purposes, working different ways. Don't replace a drive pin with brass/bronze!

Figure out what you have, and replace parts accordingly.

<<)))(((>>

JB · Aug 13, 2011

Re: "Drive" pin vs. "Shear" pin

A drive pin is a glass half full, a shear pin is often the same glass, but half empty.

boobie · Aug 13, 2011

Re: "Drive" pin vs. "Shear" pin

kfa, that is a decision only you can make. It also depends in what kind of waters you are running on.

kfa4303 · Aug 14, 2011

Re: "Drive" pin vs. "Shear" pin

I'm just gonna keep them stock. Shear pin on the 10hp and Drive pin on the 20hp. Thanks for the clarification.

1946Zephyr · Aug 14, 2011

Re: "Drive" pin vs. "Shear" pin

JB said:
A drive pin is a glass half full, a shear pin is often the same glass, but half empty.

Yep, I agree. It's just a term that some would choose to use. One or the other.

"Drive" pin vs. "Shear" pin

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