Simple Clutch Mod

Simple Electronic Clutch Modification

The Electronic Clutch EM came up with for the ePure bikes is shown below. It is part number TC01L-60403-00-00-ASM. Unfortunately, it costs $423 and is not compatible with the EM 5.7 system.

I did not want to butcher the factory wiring harness, so my addition simply plugs in. It goes between the power mode switch box and the main wiring harness. The clutch switch also plugs into it.

It went a long way toward making the bike more intuitive to ride. Several people told me they were better off removing the Oh-Shit! switch entirely and ride with just the throttle. I believe them, but this is even better. Of course, it still does not provide a range of modulation. For that, you need some sort of progressive electronic control (like the throttle, but for the clutch lever).

I had an idea of how to build something that will work even better. It is described in the Progressive Clutch section.

Credit: Electric Motion TC01L-60403-00-00-ASM for ePure

With this additional circuitry, pulling in the clutch lever connects a 1k-ohm resistor between the input to the motor controller's command voltage and ground. This causes the high-impedance source voltage that comes from the combined mode switch and throttle to be reduced significantly. (A lower voltage results in a smaller torque output from the motor.)

Due to the nature of the circuit interaction, the effect is proportionally diminished at smaller throttle openings. The 1k-ohm value was found empirically and was, in fact, my first guess.