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Thread: Gearcase Blueprinting

  1. #1
    Team Member Roflhat's Avatar
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    Default Gearcase Blueprinting

    Wondering what folk do to their gearcase to improve performance?
    Was thinking of stripping all the paint off as it's quite thick and putting on one thinner coat. It's used it salt water or else I'd polish it

    Also balancing the gears, not sure how unbalanced they generally are but I would think there's some improvement to be had there
    Anything else worth doing?

    cheers
    Thanks Ron Hill thanked for this post

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    How about running automatic tranny fluid instead of thick grease or oil? Modern manual trannies use it to reduce friction and increase gas mileage.

    Jeff
    "We live at the bottom of an ocean of air." - General Marvage Slatington

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    Team Member Roflhat's Avatar
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    Hi Jeff, I'd heard of that being done, not tried it but I might try some back to back tests to see how it performs
    cheers

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    Team Member zul8tr's Avatar
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    What kind of gear case ? Paint remove and polish up aluminum, shave bullet diameter and true up the profile to match both sides, put a point on the bullet, put a crescent lead edge on front up-right above bullet. I would leave the gears alone probably in reasonable balance and put time and $$ elsewhere.

    How high do you run the gear case?
    " Three may keep a secret if two of them are dead" Ben Franklin

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    Team Member Roflhat's Avatar
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    Standard Yamaha 70ces gear case, can't change the shape of it by adding lwp or point etc. Was going to balance the gears and re shim the gearbox at the same time

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    Team Member zul8tr's Avatar
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    I didn't suggest a LWP? As for re-shim are the gears not meshing correctly or improper gear lash? Can't you just profile the bullet and reduce the diameter a bit? Diameter effects drag, smaller frontal area is better.
    " Three may keep a secret if two of them are dead" Ben Franklin

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    Team Member Roflhat's Avatar
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    I meant I can't add anything such as lwp or a bullet point.
    The gearbox works fine but shimming it to reduce the tolerance can help reduce friction. There's regulations for the bullet and skeg thickness which I intend to take my gearbox to

  8. #8
    Team Member zul8tr's Avatar
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    Shimming the internals of the gear box if for correct gear lash for proper tooth contact. When set to proper tooth contact and lash that's it. More lash than spec just might damage the gears. Run thinner gear oil to reduce friction. I use a 75w 90 synthetic. Redline makes a low viscosity gear oil. Tranny oil suggested will work but can't say the gears will like.
    " Three may keep a secret if two of them are dead" Ben Franklin

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    Team Member Roflhat's Avatar
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    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 canditates
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    Team Member hydrospeed77's Avatar
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    Also curious to know what others use. I'm also looking for more protection than a basic oil.

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