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Shear Pin Substitute or Alternative ... Brass Is Too Soft

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  • Shear Pin Substitute or Alternative ... Brass Is Too Soft

    Does anyone know of a tried & true alternative to a shear pin (not to be confused with 'drive' pins which are usually stainless steel and have little to do with 'shear' pins). Obviously there are different specs for different engines but this isn't rocket science here ... my thread is focused on low hp outboard applications, say, under 10 hp. Is there anyone (preferably an engineer-type) who actually knows the 'general' type of alloy used. I tried using a 3/16" x 1-3/8" pin cut from a solid brass rod but it's way too soft and snapped while gliding across shallow sand bars.

    One post mentioned using a piece cut from a bronze welding rod or a soft galvanized nail and those sounded logical. I motorboat mainly at low tide and work in the shallows and need something that will prevent lower end damage but that I can get 'off the rack' at a conventional big-box store like a Home Depot or a Lowes. Buying a pack of 2 OEM pins for 5 bucks and spending 12 more dollars for shipping isn't my cup of tea (no, there are no nearby dealers). Please, no amateur alchemists or conventional advice. We all know about the dangers of lower end damage and that's fine for some. Others, on the other hand, are looking for something novel, readily available and much cheaper. If you have actual proven experience (or hard information) please pipe-in and we greenhorns will wait patiently and marvel at your expertise.


  • #2
    Re: Shear Pin Substitute or Alternative ... Brass Is Too Soft

    We have two tailwater systems here and the old timers I encountered when fishing them often used the welding rods FWIW. The only firsthand experience I can provide is my eventual insistence on no longer using motors with shear pins.
    Better to have it and not need it than to need it and not have it.
    21' Suntracker(for my girls), 16' Polarkraft MV w/ 25 HP Merc(for me), 14' Odyssey bucket raft, 16' Purple Mad River Explorer; vice-admiral's boat, but she lets me use it as long as I don't forget it's hers. Esquif Vertige

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    • #3
      Re: Shear Pin Substitute or Alternative ... Brass Is Too Soft

      I use brass rod on my 3HP motor, if I needed more strenth might go to a soft nail, steel rod or welding rod. The trick is for the pin to shear BEFORE lower end gear damage, and the harder/tougher that pin is, the better chances for damage! So roll the dice!

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      • #4
        Re: Shear Pin Substitute or Alternative ... Brass Is Too Soft

        I don't think there is too much mystery about a drive pin,just stainless steel in the correct size.
        Most motors have a cushion hub to relieve shock.The pin I looked up was 3/16 X 1 3/16. for 60-63 OMC 10 hp.
        On the 10hp the prop clutch releases at about 84-104 ftlbs torque load.
        If your moving slowly through the shallows have you given any thought to rigging
        a support so you can tip the motor for shallow drive?A magnet may be able to help tell a ss pin with more ss alloy.
        lower grade ss is more magnetic.Remember the stronger the pin the shorter the life of the prop.
        Though a pain to have to change all the time a more delicate pin may be a prop saver.
        Did your brass pin drive the prop at wot?

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        • #5
          Re: Shear Pin Substitute or Alternative ... Brass Is Too Soft

          Originally posted by lncoop View Post
          We have two tailwater systems here and the old timers I encountered when fishing them often used the welding rods FWIW. The only firsthand experience I can provide is my eventual insistence on no longer using motors with shear pins.
          Ayuh,.... Agreed,....

          But I do remember usin' an ole bent nail, scrounged from a campsite to get Home before...
          Any Grease is Better,..... Than No Grease at All.......

          Comment



          • #6
            Re: Shear Pin Substitute or Alternative ... Brass Is Too Soft

            Yeah, outboards with shear pins are a dying breed but I'm just using my backup 1968 9.5hp beast while I do a little maintenance to my everyday motor. The prop in my '68 beasty does have the internal rubber hub but the rubber was old (and dried) and had previously 'spun' and needed to be replaced. I like improvising so, rather than order a new prop or new hub, I simply drilled, threaded and pinned the prop (using three 1/2" set screws). It works like a charm with zero vibration.

            The prop was originally driven with a stainless steel 'drive' pin and this is what I am trying to outsmart and I need to replace this ss pin to prevent lower end damage since I forfeited the safety cushion of the original rubber hub. I tried the solid brass pin which I hoped would act as a 'shear' pin but as reported, solid brass ain't no good and is too soft. I need something a bit stronger. Overpriced factory pins, rusty nails and coat hangers are no solution. There must be someone out there in boatworld who has discovered the holy grail of shear pins.

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            • #7
              Re: Shear Pin Substitute or Alternative ... Brass Is Too Soft

              I used to use roll pins, there made from mild cold roll steel, and yes you might have to replace them every so offen. I take it your driving the prop though, your so called shallow sand bars.
              1987 16Ft F/S Yar-Craft
              1987, 90HP Johnson/ (3) 1971-1972, 7.5HP Merc/ 1991, 4HP Mariner/1985, 2.2HP Merc (new never started)

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              • #8
                Re: Shear Pin Substitute or Alternative ... Brass Is Too Soft

                Hi bob. These are still brass rods, but perhaps they are of a more rugged alloy. Perhaps you could enlarge the shear pin hole a bit and go one size larger. It would still be brass, but may be a little tougher.

                http://www.duckworksbbs.com/material.../rod/index.htm

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                • #9
                  Re: Shear Pin Substitute or Alternative ... Brass Is Too Soft

                  Thanks to both of you for clever alternatives ... I was thinking of cutting grooves into a steel pin when, lo and behold, I found this old Popular Mechanics link: ( http://books.google.com/books?id=teE...pin%22&f=false ). Where there's a will there's a way.

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                  • #10
                    Re: Shear Pin Substitute or Alternative ... Brass Is Too Soft

                    I was thinking an aluminum rod might be the ticket
                    Kevin

                    But, where are the reevets?
                    1981 Wellcraft V-20 CC Fisherman (FREE BOAT)
                    1989 Wellcraft Monte Carlo 28(Build thread here)
                    1992 Hotsports Jet'n'Cat Yam 701 WR3 drivetrain "SS George Washington"
                    90's Yamaha WRIII and a pair of 95 Kawasaki ZXI-900's
                    Fresh clean cheap oil is better then old dirty expensive oil any day
                    sigpic

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                    • #11
                      Re: Shear Pin Substitute or Alternative ... Brass Is Too Soft

                      Good 'ol PM. Always so clever.

                      Comment



                      • #12
                        Re: Shear Pin Substitute or Alternative ... Brass Is Too Soft

                        Originally posted by bobgritz View Post
                        Thanks to both of you for clever alternatives ... I was thinking of cutting grooves into a steel pin when, lo and behold, I found this old Popular Mechanics link: ( http://books.google.com/books?id=teE...pin%22&f=false ). Where there's a will there's a way.
                        PM claimed these were bronze. If indeed this is true, McMaster-Carr has a big selection of bronze rods.

                        http://www.mcmaster.com/#red-metals/=gdp5xn

                        I would bet that one of these would be just the ticket.

                        TerryMSU

                        Comment



                        • #13
                          Re: Shear Pin Substitute or Alternative ... Brass Is Too Soft

                          Originally posted by bobgritz View Post
                          does anyone know of a tried & true alternative to a shear pin (not to be confused with 'drive' pins which are usually stainless steel and have little to do with 'shear' pins). Obviously there are different specs for different engines but this isn't rocket science here ... My thread is focused on low hp outboard applications, say, under 10 hp. Is there anyone (preferably an engineer-type) who actually knows the 'general' type of alloy used. I tried using a 3/16" x 1-3/8" pin cut from a solid brass rod but it's way too soft and snapped while gliding across shallow sand bars.

                          One post mentioned using a piece cut from a bronze welding rod or a soft galvanized nail and those sounded logical. I motorboat mainly at low tide and work in the shallows and need something that will prevent lower end damage but that i can get 'off the rack' at a conventional big-box store like a home depot or a lowes. Buying a pack of 2 oem pins for 5 bucks and spending 12 more dollars for shipping isn't my cup of tea (no, there are no nearby dealers). Please, no amateur alchemists or conventional advice. We all know about the dangers of lower end damage and that's fine for some. Others, on the other hand, are looking for something novel, readily available and much cheaper. If you have actual proven experience (or hard information) please pipe-in and we greenhorns will wait patiently and marvel at your expertise.
                          if you're running onto sand then your shear pins are doing their job breaking before your gears do...the stresses in these little outboards have fairly narrow limits sometimes even putting too thick oil in the gears can rip them out make plenty from 3/16 brass this'll cost peanuts and save your motor for years if your doing a lot of running over sand fit a skeg on your boat that can be lifted to stop you getting stuck but which projects enough to protect your prop .....try digging wet sand it's pretty tough stuff ....mud's soft but not sand... Good luck!

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                          • #14
                            Re: Shear Pin Substitute or Alternative ... Brass Is Too Soft

                            Originally posted by RODERICK FYSH View Post
                            if you're running onto sand then your shear pins are doing their job breaking before your gears do...the stresses in these little outboards have fairly narrow limits sometimes even putting too thick oil in the gears can rip them out make plenty from 3/16 brass this'll cost peanuts and save your motor for years if your doing a lot of running over sand fit a skeg on your boat that can be lifted to stop you getting stuck but which projects enough to protect your prop .....try digging wet sand it's pretty tough stuff ....mud's soft but not sand... Good luck!
                            February 23rd, 2012
                            Ayuh,.... Welcome Aboard,.... Please don't be postin' in the Archives....

                            that's what that big red banner was all 'bout....
                            Any Grease is Better,..... Than No Grease at All.......

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