Hi everyone, saw and sosidge pretty much got it right. Cogging is cuasing by the motor is not reving up fast enough to be in sync with the controller. It should only happen to the sensorless system, unless there is something seriously wrong with the sensored system.

It basically happens when you apply the throttle, the controller will energize different pole of the coils in the can to keep the motor turning. In other words, there is a time of how fast the controller change the to next zone. The controller assumes the motor will keep up with the timing, but when car is over geared, or the battery doesn't provide enough power. This cause the motor to bog down.

On the sensored base system, the controller is waiting for the feedback that's coming from the hall sensors. So, it doesn't assume the position of the rotor, which shouldn't have any cogging problem. I would advise you to first make sure all the sensor wires are connected and not cut. Second, try a smaller pinion, maybe 2 to 3 teeth smaller.

BTW, there are several times in the magazine, Hi-torque's R/C car, the editors completely mis-understood the meaning of cogging. Somehow they get the idea of cogging as the drag brake from the brushed motor.

Good luck