After my torque arm failed and caused some bother with my new motor, I didn't have much luck getting something suitable to replace it with. Though DoctorBass had a batch of very nice torque rings made (http://endless-sphere.com/forums/viewtopic.php?f=3&t=34150&p=496417&hilit=+torque+steel+laser+cut#p496417
) they're not suitable for the swingarm of the kind of scooter I have.
So I thought I'd dip into the the world of CAD design and fabrication of custom parts. Here is my first attempt. I wanted something decent to replace the flimsy things that come with the bike/motor...
I finally took delivery of my order of the real thing: A batch of 12mm torque arms manufactured out of 6.3mm laser-cut steel. Here's one shown next to one of old ones. They have a 6mm hole for the adjuster bolt, and as far as I know are suitable for most 1400W/1500W motors. The torque slots are slightly wider as the 1500W motor has a 16mm axle on the cable side, as compared to the 14mm on the 1400W motor, though the slot diameter required (on mine at least) is 12mm on both. I've also made mine longer, with a wider adjustment slot so that the rear wheel can go back further to accommodate larger tyres. I got a batch of them, so there's plenty left to go in my little shop:
And here it is on the new motor hub, next to the even worse torque arm that came with it (those are the ones that failed):