centex error- For the 8x1 I would start at 8.8 on the gear ratio and go from there. With my Mission 2 I run a 8x2 and I start with a 25 pinion gear on 128 spur gear. I havent run a 6x1 or a 7x1 so the only thing I can recommend is start one tooth lower on each motor from the 8x1. So I would start with 24 pinion for the 7x1 and 23 pinion for the 6x1 that is were I would start with my car.