Jackshaft rear engine mount mod

Discussion in 'Transmission / Drivetrain' started by Arty, Feb 20, 2015.

  1. Arty

    Arty Active Member

    I installed a Sick Bike Jackshaft kit on my bike last summer, and after riding for a couple of weeks, found that the engine seemed to be twisting in the frame, causing poor chain alignment.
    Upon close inspection, I found that amongst other things, the rear engine mount of the jackshaft kit seemed to have twisted out of shape, and was also not indexing onto the seat post tube as well as I'd have liked.
    Anyway, to solve the issue, after straightening the jackshaft bracket, I built a stiffener to slide inside the jackshaft bracket that fits between it and the seat post tube. that extends far enough down to also straddle both jackshaft bearings. It's not real pretty, and there's a ton of MIG wire in it - but hey - it works.
    The two holes just above the jackshaft bearing saddles are for a piece of ready rod that slips through the whole assembly after installation in the frame, with two nuts per side to box the whole thing for added rigidity.
    I know this sounds a bit complicated, but anyone with a jackshaft kit will likely understand.
    It's a bit on the heavy side, but in conjunction with an improved front mount, my engine is now rock solid in the frame.
     

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  2. Vapourtrail

    Vapourtrail New Member

    this is what my shift kit has got

    a tube spacer that the bearing sleaves into

    P1010047.jpg

    I found when using the zorst pipe clamps the sides of the frame would bend inwards

    the tube spacer keeps the frame parallel and bearings in alignment

    and I dont use zorst pipe clamps

    P1010051.jpg
     
  3. Arty

    Arty Active Member

    Vapourtrail:
    That's a mean looking bike you've got there! I agree with you 100% on the pipe clamps.
    I usually split a piece of sched40 pipe (of the same inside diameter as the bike tube's OD) longitudinally, then cut a piece of it about 1.5 inches long with two notches cut into it to slip under the "U-bolt" to act as a saddle to spread out the clamping force over a larger area of the bike tube. That way you'd really have to get ignorant to squash the frame tube.
     
    Vapourtrail likes this.
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