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  1. #31
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    May 2011
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    Murray Bridge S Aust.
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    71
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    Nice looking bike, what year is it??
    Kryn
    To grow old is mandatory, growing up is optional.

  2. #32
    Join Date
    Oct 2004
    Location
    Southern Highlands NSW
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    Another photo shows the more usual type of brake, which has one lever on the brake plate.
    Mine has two levers with a linking rod, which is an obstruction that requires the speedo cable to exit at a greater angle.
    That needs to have the different helix angle on the driven gear.
    Attached Images Attached Images

  3. #33
    Join Date
    Oct 2004
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    Southern Highlands NSW
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    Quote Originally Posted by KBs PensNmore View Post
    Nice looking bike, what year is it??
    Kryn
    Thanks, it's a modified 1974 model, originally a 350 trail bike.

  4. #34
    Join Date
    Oct 2004
    Location
    Southern Highlands NSW
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    Quote Originally Posted by Mk1_Oz View Post
    Why does it have to be metal? I would have thought a dodo drive could easily be nylon. I am sure I have seen nylon ones in cars b4.
    That's right, I've seen that too, now that you mention it.
    It could be another solution to try.
    Getting the software right could be a challenge though?

  5. #35
    Join Date
    Oct 2004
    Location
    Southern Highlands NSW
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    Quote Originally Posted by shedhappens View Post
    A sweet 450 desmo, thanks for the pic's.

    I think I have one of the first ducati engines somewhere, 50cc 4 stroke with exposed pull rods.
    They made them to bolt onto push bikes.
    It's a 350, almost identical to look at.

    I used to think the Ducati 50cc pullrod 4 stroke bicycle motor was the ultimate of its type, until I learnt about the Bugatti effort.
    It has twin overhead camshafts and is supercharged, about 10cc.
    the Bugatti revue, 12-1, Bugatti T72 fact sheet and photos

  6. #36
    Join Date
    Apr 2019
    Location
    Adelaide
    Posts
    589

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    Quote Originally Posted by nadroj View Post
    ...Getting the software right could be a challenge though?
    If you are not a genius on CAD I am sure there are some smart cookies on this site who could draw it up. There will almost certainly be some locals who can nylon print. I would try my 3D printer for you but so far I have not managed to get decent and accurate enough prints yet.

  7. #37
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,541

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    Gears when used as skew gears rub a bit - not sure a 3D printed one would last long. The helix angle is the critical bit. Once we know that, the maths can leap into effect and it will probably work out.

    Michael

  8. #38
    Join Date
    Feb 2013
    Location
    Laidley, SE Qld
    Posts
    1,038

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    In the 90s Toyota were using a metal helix gear in the gear box to drive a nylon gear on the bottom end of the speedo cable. I have a nylon gear somewhere I'll post a photo.

    Quote Originally Posted by Mk1_Oz View Post
    Why does it have to be metal? I would have thought a speedo drive could easily be nylon. I am sure I have seen nylon ones in cars b4.

  9. #39
    Join Date
    Jul 2006
    Location
    Athelstone, SA 5076
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    4,255

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    Quote Originally Posted by nadroj View Post
    Due to the popular demand of one, here's some pics.
    mmm cafe racer?...do you really need a speedo

  10. #40
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    Apr 2019
    Location
    Adelaide
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    Nad, I have just done a quick google for "speedometer nylon gear" and there are plenty of cheap alternatives. If I was you I would be working out the overall gear ratio you need then finding a pair of gears pre-made - it them doesn't matter what the MOD or helical angle is just as long as the 2 match each other. You might need to modify them slightly to fit your shafts.

  11. #41
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    Aug 2008
    Location
    Melbourne
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    34
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    Quote Originally Posted by Mk1_Oz View Post
    it them doesn't matter what the MOD or helical angle is
    Yes it does. If the gears were parallel it wouldn't matter, but OP has said that the gears are on crossed shafts; if the helix is wrong they will not cross at the proper angle.
    Gear cutting specialists and general engineers www.hardmanbros.com.au
    Fine pitch gear cutting from 0.1 Module www.rigear.com.au

  12. #42
    Join Date
    Feb 2013
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    Laidley, SE Qld
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    Toyota G52 etc series gearbox. Right angle speedo drive out of the side of the box, nylon gear is 23.5 OD x 14 long.

    IMG_3971.jpg

  13. #43
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    Apr 2012
    Location
    Healesville
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    2,129

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    I think all of the cars that i worked on in the 70's & 80's had a plastic gear on the mainshaft and a plastic gear on the speedo cable, the gears in on the speedo cable were color coded and slightly differant diameters, i was a mechanic in the police workshops and we would drive a car over a measured kilometer and take note of the odometer reading and then fit the right coloured gear to get the odometer calibrated to the spec it needed to be.
    Then the speedo/needle spring would be adjusted/calibrated by using a machine that drove the speedo, the machine had a calibrated speedo and you used that to set the other.
    I dont recall ever seeing a plastic gear on any motorcycle that i have worked on

  14. #44
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    Apr 2019
    Location
    Adelaide
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    589

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    Quote Originally Posted by elanjacobs View Post
    Yes it does...
    No it doesn't. I am talking about buying a pair of matched gears not just a single gear that needs to mesh with an existing gear.

  15. #45
    Join Date
    Oct 2004
    Location
    Southern Highlands NSW
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    Quote Originally Posted by eskimo View Post
    mmm cafe racer?...do you really need a speedo
    I want a speedo.

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