Impedance Matching

I have a simple DC motor with a gearbox that I need to extract the maximum power from to partially charge a super capacitor. The torque available to turn the gear is fixed and I cannot add more gears to it. This project is to maximize the power efficiency between a geared motor and a supercap and calulate the values of all components in this circuit. I already have both a single schottky diode and a schottky diode rectifier, but it seems there is an impedance mismatch, the capacitor does not get charged quickly enough, and not all the mechanical power is used. I would like a tested circuit design, and possibly a formula proving this is the optimal circuit. Approximate specs, I will give the exact specs in PM: A very small DC gearbox motor produces about 3v, 170ma on a completely shortened circuit, going directly into amp meter. The torque force is about 2kg pull, about 2cm from the center. Fixed. I would like to use the same force to charge the supercap. However, once a single diode or a rectifier is connected, the gearbox is no longer stalled, and gives way, even on a completely discharged super capacitor with very low ESR. I understand that the suepercap's resistance will raise and the amount of torque needed will be less. I am planning to use larger capacity supercap and not charge it fully. Again, the task is to show me how I can use *all* of my 2kg torque without an additional gearing. I need some details from you about the proper technique to accomplish this so I can award you this project.