On the subject of plastic spur gears...I was running an 8E 45t plastic spur in my Muggy (until tonight, that is). I recently put some larger tires on it - just to try out. I'm running a CC1518 on 4s geared for 45mph or so and it weighs 12.5 lbs. rtr:
I've run this set-up a number of times now, but tonight after running through almost a whole pack, I gave a hard pull on the throttle and my plastic spur now looks like this:
I thought it might have got too hot, since it was about 95F outside, but the motor was about 145F, the CD about 135, and the outer edge of the spur itself was 125. So I'll put a 46t steel spur back in this thing - and save my plastic spurs for my 1/8 buggies.