Metal or Plastic center diff spur gear?

[aqwut]

I use Kyosho nylon spur and HPI Savage Spur gears on my 18Lbs GST, and haven't had any problems.. Mind you that I use mechanical brakes... I had chipped pieces of metal stock on the bearings/shaft/can of my brushless motors. Some how, those small shavings always seem to find a way to get inside the motors. Just a thought.