Big twin 40hp shear pin material?

[matt167]

I sheared the pin on my 1966 Johnson Super Seahorse Deluxe 40hp. Must have been old because it sheared in the test barrel.

Is there any 1/4" material I can cut new pins out of that is soft enough to work correctly?

 

[F_R]

It is not supposed to be "soft" nor shear. It is supposed to be a stainless steel DRIVE pin.

 

[racerone]

You can use a brass pin as long as you have spares and tools handy.----Make sure your last spare pin is the stainless " drive pin " .

 

[gm280]

Are you talking about the flywheel pin or the prop pin? The prop pin is pretty hard material. Certainly not aluminum or anything like that.

 

[matt167]

prop pin. The one I pulled that was sheared, was a brass like material.

 

[racerone]

You can buy brass shear pins at 29 cents each.----Or buy new props at $125 each.-----A choice you have to make.

 

[oldboat1]

I like brass shear pins for fishing -- trolling with smaller motors through weed beds and some shallows. I use stainless drive pins for larger motors -- never been sure that the torque of a 40hp wouldn't be enough to shear a brass pin, but not really aware of a case where that happened.

 

[racerone]

The issue is the shifting.-----Some folks will shift a 40 HP motor when idling too fast.------Do that a few times and the pin shears.-----Back in the day folks accepted having to change a shear pin.-----The general public today does not put up with that inconvenience !!

 

[oldboat1]

Och ja, as my Dad would have said. He would not have been a big fan of hole shots -- not much for WOT either, although he let me do it.

 

[F_R]

The issue is the shifting.-----Some folks will shift a 40 HP motor when idling too fast.------Do that a few times and the pin shears.-----Back in the day folks accepted having to change a shear pin.-----The general public today does not put up with that inconvenience !!

Ever change a shear pin in the middle of the lake? Dang near impossible to reach it without falling in. Or pull the motor off and into the boat. Or jump in the water and do it while swimming (????). The last pin I changed, I paddled the boat ashore to change it. This little guy was on the shore, waiting for me.

 

[matt167]

I bought some 1/4" aluminum rod locally that I think has the right strength compared to what was there, and I bought a bunch of 1/4" brass rod online.

There is no marine store local anymore, and Napa claims not to be able to get anything anymore either

 

[racerone]

Carl ---sold a lot of his motors with the " shear proof " propellers.-----As motors got bigger the job of changing the pin got bigger if not impossible..----The Martin outboards had the swivel feature.----You swung the lower unit so that the prop was right beside you.----No chance of loosing parts or tools.----So every boating area . boat and motor is different.

 

[matt167]

If I shear it, I'm going to have an electric or a gas motor on the bracket beside it to bring it back to the dock, where I could either pull it, fix and re launch or do it at the dock

No Crocs, Gators or any other predators where I boat, so I could go swimming to do it, but I'd drop the prop most likely.

 

[gm280]

I bought the actual shear pin for my '76 Johnson OB as original part from the manufacturer and they definitely were not aluminum or brass. They were either stainless steel or an alloy of something like that. JMHO

 

[racerone]

It is a stainless drive pin installed at the factory !!----The prop has a rubber hub to absorb the shock of hitting something.----But often it damages the prop !

 

[dingbat]

I bought some 1/4" aluminum rod locally that I think has the right strength compared to what was there, and I bought a bunch of 1/4" brass rod online.

Aluminum 12,000 - 18,000 psi
Red Brass 35,000 psi
304 stainless 75,000 psi
Low carbon HRS 50,000 psi

 

[racerone]

Tensile strength or shear strength ??

 

[dingbat]

Tensile strength or shear strength ??

Shear

 

[matt167]

Aluminum 12,000 - 18,000 psi
Red Brass 35,000 psi
304 stainless 75,000 psi
Low carbon HRS 50,000 psi

So the aluminum will be out. I knew it was softer but got it because Lowes had it.

 

[matt167]

Why does the pin look like bronze? It appears to be 78,000 PSI shear strength if it is bronze? Or could it just be discolored?