need to find small transmission

Discussion in 'DIY Marinizing' started by fishon91, Feb 11, 2011.

  1. fishon91
    Joined: Dec 2007
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    Location: wishin i was in florida, LA

    fishon91 Junior Member

    im designing a boat(just in very early design stage) powered by twin vanguard 35's. i need to find a transmission that has only a reverse-nuetral-forward and about a 1.4:1 ratio in forward, maybe 1.7:1 in reverse.
    how do i go about finding something like this? i have no experience in regular boat design. my whole life has revolved around mud motors, so i know not much about inboards or even outboards.
    this is just a project i am designing for a buils years down the road and thanks for any help.
  2. whitepointer23

    whitepointer23 Previous Member

    hello fishon, check out hurth transmissions. they have small models, don't know why you want different ratios for forward and reverse though.
  3. CDK
    Joined: Aug 2007
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    CDK retired engineer

  4. fishon91
    Joined: Dec 2007
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    Location: wishin i was in florida, LA

    fishon91 Junior Member

    thanks yall, and sorry for bringing back an abandoned thread.. i dunno why i didnt respond..
    id want a lower revers gear for power, lower rpms and more power would be more necessary in reverse. this is a mudboat type design so reverse would be mostly necessary for helping get out of sticky situations. i thought reverse was typically a lower gear in most transmissions.
  5. whitepointer23

    whitepointer23 Previous Member

    not in marine trans. r&f are same ratio. you might have to use a car transmission for what you want. i would have thought correct prop selection would give the result you need with out having to use odd ratios.
  6. EvilBoater
    Joined: Sep 2011
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    Location: NH

    EvilBoater New Member

    Most of the small Transmissions I that have seen are limited to the 16 H.P. range. (comet makes an F-N-R gear box, Glen-L has a F-N-R design for a small gas engine as well) I do have a design for a chain and belt driven transmission that utilizes electric clutches from a lawn tractor to select from F-N-R as far as the "Gear Ratio" this all depends on the size of the pulleys. I have never tested it with an engine bigger than 16 H.P. BUT I would imagine if you could get strong enough and thick enough belts, it might handle a lot more H.P. OR you could try using a 4x4 transaxle out of a 1970 Dodge Ramcharger One ton OR a small 3 speed transmisson out of a chevy vega Rear wheel drive. (Clutching would be your only problem with the transmission and transaxle) If you want the pulley set up plans contact me and you can have them.
  7. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    Go to a marine junk yard. Marine engine shops have used gearbox's stacked up like cord wood. See what they have, research its suitability, then buy one . A good price would be 10 cents on the dollar. Transmissions are durable and rebuildable.
  8. JakubT
    Joined: Mar 2015
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    JakubT Junior Member

    I am also looking for some revers marine transmission for gas engine 60-80 hp around 5000 rpm and it seems only available ones are vintage pieces. Even chinese couldnt help:)

  9. muskrat215
    Joined: Jun 2009
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    Location: Murfreesboro, TN

    muskrat215 New Member


    You could make your own 'transmission.'

    I am thinking of using hydraulic motors to run a retractable 'pod.' Put one motor on your engine and the other motor mounted to your prop. Then you just need a directional valve for forward/reverse.

    I have heard other guys running them on water with glycol, but I had a different idea... I worked for a food company once that ran all of their hydraulics on vegetable oil. Totally biodegradable and even edible. In a pinch, you could probably get replacement oil from restaurants. lol
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