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Thread: Gearcase Blueprinting

  1. #11
    Administrator Ron Hill's Avatar
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    Nov 2004
    Tustin, California
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    Default Shimming is Correctly is Best

    Quote Originally Posted by Roflhat View Post
    Alright, I've never tried shimming the gearbox but heard you can shim it tighter to gain some rpm. Not sure if there's much to be gained by balancing the gears seen as the diameter is relatively small but any gain is of course welcome
    Did you do any back to back tests with the different gear oils? I looked into it a while back and it looked like Amsoil 75w90 or Castrol hypoy 80w90 looked like decent candidates
    Shimming it looser, may increase your RPM til it blows up. Raise the motor 1" and get a new propeller. This will do more than all the blue printing a gearcase can ever gain. Get the gearcase out of the water. (Less drag)... Sharpen the skeg...
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  2. #12
    Team Member fs5's Avatar
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    Jun 2008
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    Hi mate you can get the gears lapped so they mesh together better . Haven’t heard about shimming tighter.
    Haven’t tried tranny fluid in mine yet haven’t been brave enough. They reckon if you do you should change it after a couple hours. But they say it works.
    Grinding reverse gear off helps , can also trim a bit off the bottom of your skeg. But it’s minimal gains.

  3. #13
    Team Member Roflhat's Avatar
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    Jul 2011
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    I don't mean shimming it so the gears are too close together, just taking the tolerance closer to what it should be from factory.

    Hey Jake, lapping looks like the way to go thanks mate. Did consider removing the reverse function but the rules say it has to be able to reverse.

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