Stuttering motor

Radio Control Car Action, Oct 2003 by Higgins, Matt

I have a Traxxas Stampede that came RTR with an ESC. Whenever the truck goes over jumps, it dies when it lands. When I pick it up, it suddenly starts up again. It then runs fine until I take another jump, after which it dies again. The odd part is that the steering works when it coasts after a jump; I can steer it back to me, but the motor doesn't start again until I pick the truck up. How can this be?

Bob Dorman

It sounds as if your truck is possessed. Have a priest perform an exorcism; your Stampede should return to its friendly and well-running previous state. If that doesn't work, check your motor and ESC; first, take the motor out to clean it with motor spray. If you replaced your sealed-end-bell motor, pay close attention to the brush hoods because | dirt can build up in there and prevent the brush from traveling properly and making contact with the comm. This is called a "hung brush," and it causes problems similar to those you described. It also sounds as if you might have a loose wire that is breaking contact because of the jolt when the truck lands. Two wires run from your ESC to your motor; one of these may have a faulty connection. The loose wire is probably at the ESC end because when a wire falls off the motor, it's completely off. In contrast, the end of an ESC wire that's barely held in place by the ESC case might be loose enough to allow the interruption of the current flow. You can take your ESC apart and solder the wire back on, or send the ESC back to its manufacturer. Take the ESC apart only if you're very knowledgeable about electronics; you'll most likely void your warranty, and you risk doing much more harm than good if you solder it imprecisely.