ORIGINAL: Perry S.
Not sure they exist. The HL pinion is 8 tooth on a 2.3 mm shaft. I thought I saw a 7 tooth one before but can't remember where. Your kinda between a rock and a hard place here. A low turn motor will surely pull too many amps for the HL electronics to bear. Gearing is the only way to go if you want more torque to the tracks.
Perry
Perry,
The pinions on the two stock HL gearboxes on my desk (1 plastic 1 metal) are 10 tooth. Perhaps you were thinking of 8 teeth as the smallest you've seen, not as tht stock pinion?
David