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  1. #1

    Default Shear Pin for 1967 Chrysler 20HP?

    Hi all. I have a 1967 Chrysler 20HP motor. The model # is 20701 and the serial # is 3517. I am wondering where I can get some shear pins for it? Are there other pins that may fit it? I am having no luck around Indianapolis trying to find them. Thank you in advance.

  2. #2
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    Default Re: Shear Pin for 1967 Chrysler 20HP?

    that is not actually a shear pin on that motor. It is a drive pin. Stainless rod of the right diameter cut to the right length will work fine.

  3. #3
    Supreme Mariner Frank Acampora's Avatar
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    Default Re: Shear Pin for 1967 Chrysler 20HP?

    Or buy a long stainless bolt of the correct diameter at Lowes or Home Depot and cut off the threads and head. Be certain the bolt is long enough so that the unthreaded portion is adequatly long to pass fully through the prop hub.

  4. #4

    Default Re: Shear Pin for 1967 Chrysler 20HP?

    So will this pin break if I hit something? Or will it just fry my lower unit? I have never had a motor this old and I would like to do everything I can to keep it working.

  5. #5
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    Default Re: Shear Pin for 1967 Chrysler 20HP?

    I believe the hub absorbs the shock.

  6. #6
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    Default Re: Shear Pin for 1967 Chrysler 20HP?

    Where are you located? What or what kind of water will you be boating on? Are there lots of stumps or other things you can hit? I lived in South Carolina for 7 years, fished Santee- Cooper. It is full of things to hit. At that time I had a 7.5 motor and just used some wires I cut off a old outdoor chair. Almost like a coat hanger material. I kept a dozon in my tackle box. I was constantly hitting things and shearing the pin. I went the cheep route. So you can use anything that fits the diameter of the hole and cut to the length you need. The strength of the pin will be based on the force of the motor.

  7. #7
    Supreme Mariner Frank Acampora's Avatar
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    Default Re: Shear Pin for 1967 Chrysler 20HP?

    The prop shaft is splined for positive prop drive and the prop hub has a rubber internal donut. The theory is that if you hit anything the rubber hub will absorb the shock---MAYBE--- Hit anything hard enough to have the rubber function and you will still bend the prop though

    The drive or thrust pin only takes forward and reverse thrust loads and keeps the prop from sliding down the prop shaft and contacting the gearcase. it also keeps the prop from sliding off during reverse operation.

    While I personally do not like this arrangement, especially on the big engines, I have a number of Chrysler engines from 8 to 125 HP that use these thrust pins and I have yet to see a pin shear. I have run props (well, my son and daughter did) into rocks and the prop was rather well bent but the pin was not even harmed. Another drawback to this system is that if you get some line (rope) or similar material wrapped behind the prop, it will force the prop against the pin so hard that you will need a punch and hammer to drive out the pin; you will not be able to clear the line or change the prop on the water.

    The tailcone retains the thrust pin and it is held on with a cotter. If the tailcone is loose and the rattle bothers you, just insert a suitably sized O-Ring into it to take up the slack.

  8. #8
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    Default Re: Shear Pin for 1967 Chrysler 20HP?

    Quote Originally Posted by Frank Acampora View Post
    The prop shaft is splined for positive prop drive and the prop hub has a rubber internal donut. The theory is that if you hit anything the rubber hub will absorb the shock---MAYBE--- Hit anything hard enough to have the rubber function and you will still bend the prop though

    The drive or thrust pin only takes forward and reverse thrust loads and keeps the prop from sliding down the prop shaft and contacting the gearcase. it also keeps the prop from sliding off during reverse operation.
    I have the same motor and the prop shaft is not splined. The pin he is talking about is the drive pin. And to an earlier post a coat hanger wire for a drive pin will shear the first time he tries to plane the boat. Better to get the right pin and use it.

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