[frizzen]

The necklace idea for U-joints would work pretty well if you can find the right "box chains". They ought to be dirt cheap if you get them through the right place. If you cold-solder (lead) a couple joints at each end for connection points, it should work perfectly Anyway, you may still run into problems with turns since there's no diff.

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Maddog,

Just wire the entire (dual motor, dual battery) circuit in SERIES, but make sure that your contact points for the motors are wired up so they spin properly for your setup.