Keep it at 6V and wire the two motors in parallel (+ of the existing motor also goes to + of new motor; likewise with -).
Note that the peak current draw will now be 2x, which may be marginal with existing wiring and/or may stress the battery.
Stuck my first problem with the steering mechanism[…]
Fantastic! I was wondering if noone had done a […]
NICE ... that is sweet.
Your batteries have to be matching amperages, manu[…]