Yep, I've been thinking about these helical gears... To use them we'd have to move one of the shafts down quite a lot. I dont think we have the space, but I'll look at it again when I go to school tomorrow.
We use "extra" bevel gears (that means they were not in the kit). We talked about all these drivetrain problems today, and it looks like we need to support the shafts better (they started to bend - we have tons of power!
). This may eliminate the grinding, even with the same type of gears.