Jackshaft questions

Discussion in 'Hubs, Gearboxes, Sprockets and Chains' started by PsychDoc, Nov 29, 2019.

  1. PsychDoc

    PsychDoc Member

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    Hopefully the pictures will provide most of the information needed. It’s going to be a tight fit. The ? Proper orientation will require elevating the plates to clear the engine base- and only give about 1/2” of adjustment. The engine is as far forward as reasonable. The yellow mark up is some of the case I believe I can trim away. The vertical orientation is a thought but I don’t know if that gives much adjustment on the chain. Couple questions-


    How much adjustment does one need? Like half a links worth?


    Why is there an extra hole in the plate? And how much of the plate can I safely trim?
     

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  2. MotoMagz

    MotoMagz Well-Known Member

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    I see nuts and bolts... is it bolted through seat tube? If not why not leave everything facing like it is but put js shaft behind seatpost tube?
     
  3. PsychDoc

    PsychDoc Member

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    Sorry about that- it’s not bolted to seat tube. And unfortunately there is even less room behind the seat tube. Stand by..., okay this pic gives a good view. I want to avoid altering the frame
     

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  4. PsychDoc

    PsychDoc Member

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    I also considered under the motor- but my input sprocket would hang below the frame by... wait a minute... maybe that’s not to bad. I’m thinking 26 tooth, that’s about 3.5 inch diameter.
     

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  5. Barnfresh

    Barnfresh Member

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    I ran across this and saved it when I was looking to do a build that required a jackshaft. Pretty simple eh...
     

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  6. FOG

    FOG Well-Known Member

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    I'm working out the details on a jackshaft myself and I'm thinking I want a link and a half of adjustment. On a 4xx chain that'd be 3/4". But I've never built one before so what do I know?

    Plan A for me is to rotate the jackshaft housing in a pair of plates I'll weld on the seat tube vs sliding it, and here's a pic of what I think will be enough adjustment.

    DSCF0832[1].JPG
     
  7. PsychDoc

    PsychDoc Member

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    Well FOG, you seem to know that the pitch for a 4xx chain is 1/2 inch. My thought is that one full link is all the adjustment we need. Right? And, if the pitch (rollers center to center) is 1/2 inch then one link is 1 inch. And we aren’t using any fancy pants half links. And the length of adjustment is distributed over ‘two chains’- top and bottom right? So the maximum shaft movement a single link can require is 1/2 inch. Right? Or am I drunk?
     
  8. FOG

    FOG Well-Known Member

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    I'm with ya Doc. I was just adding an extra 1/4" for chain stretch and some fudge factor.

    Another clue I collected along the way was when I bought some Origin8 horizontal chain adjusters for my back axle that have a 3/4" range.

    https://www.ebay.com/itm/CHAIN-TENS...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

    But who knows? Hopefully one of the more experienced guys will check in with some words of wisdom.
     
  9. PsychDoc

    PsychDoc Member

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    I spent half the day staring and thinking and stretching chain for the pedal side. I wish I could say more was completed, but I believe I have a fair idea of how it will come together. And I found what appears to be a good supplier for all things chain, bearings, sprockets- I have not ordered from them yet.
    https://redboarchain.com/

    *edit- if it’s poor form to mention suppliers, especially the untried, let me know and I’ll avoid it in the future.
     
    #9 PsychDoc, Nov 30, 2019
    Last edited: Nov 30, 2019
    indian22 likes this.
  10. indian22

    indian22 Well-Known Member

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    Thanks for the supplier info Doc. I've an order ready to go for Red Boar & forum monitors will let us know what's out of bounds, though other suppliers may protest as well.

    Rick C.
     
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  11. PsychDoc

    PsychDoc Member

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    Thanks Rick- let us know how they do.
     

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