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Sidewinder gear efficiency

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  • Sidewinder gear efficiency

    Due to the shape and dimensions of the Slot it pinion gear teeth, the contact areas are different for each number of teeth.

    The 11 tooth gear has the least amount of contact area where the teeth touch the spur gear‘s teeth. The 10, 12, and 13 tooth gears have a larger contact area.

    This larger contact area could create more friction and reduce the efficiency of these gear sets.

    I have found the 10, 11, and 12 tooth pinions used with any spur gear give good performance.

    The 13 tooth pinion used with the 32 and 34 tooth spur gears is very noisy and demonstrated a loss in power shown by the drop in top speed on the track.

    The conflict between the 2.91:1 ratio of the pitch circles of the pinion and spur gear, and the numerical gear ratio, could also create a loss in efficiency.

    The 6mm pitch circle and 17.5mm pitch circle are the imaginary non slipping mating surfaces of the of the 6.5mm and 18mm gears.

    Changing gear ratios of a few hundredths, could give mixed results depending on the efficiency of each gear set.

    The 11 tooth 5.5mm pinion also showed a loss in efficiency when used with different crown gears. This loss was also demonstrated by a drop in top speed on the track as shown in this demonstration.


  • #2
    No meshing around, here

    Dave, does this indicate that you were using the 32t 18mm spur? (11/32 = 2.91:1)

    It looks more like the colour of a 34t in the pictures.

    I note that in the Racing Parts Brochure, either the 10t or 11t pinions in combination with the 19mm 34t, 36t, or 38t spurs appear to be favoured as the optimum pairings. Have you compared the same setups between 18mm & 19mm spurs, either photographically or in track testing?


    • #3

      The 2.91:1 ratio is for the pitch circle for all of the 6.5mm and 18mm gears. It is the imaginary line where the gears mesh.

      This ratio of the pitch circles remains the same even though the numerical ratio changes.

      This is why I said this could create a conflict when the pitch circle ratio and the numerical ratio are different, and create an efficiency problem.

      I never have compared the 19mm spur gears.

      The only Slot it gears that have ever shown a measurable loss are the 13 tooth sidewinder pinion gear, and the 11 tooth inline pinion.