Ok, 2 stage, MOD 1, wider then 8mm. Go for the 8.69m/s (31km/h). Thanks guys. I prefer to use m/s because our arena is 4.8m and I can gauge off that.

I can't drop in a pre-built gearbox because I'm using an old chassis. That chassis is made from 5mm wear plate and has taken a lot of hits from spinners with no damage, so I can't see any reason to chuck it in the bin. Its only as wide as 2 x 300W scooter motors, which makes it all a challenge.


Second question. In my beetle weight brushless gearbox I used Shapeways to print the gearbox housing which I then bolted into a biscuit tin. I was plaining to use the same thing in Vendetta, with a 3D printed housing that matched the scooter motor bolt pattern.
Here's a piccy of what I did with the beetle.