XRAY - Model racing cars

Cutting both leading and trailing edges of a brush equally will not effect overall timing, as long as both brushes are cut the same. There are only a select few motors that require (for good performance) cutting only one side of the brush (leading OR trailing, but not both). You can't apply a blanket statement to motors. Every model of motor is different and requires different techniques to get the best performance. Many times you can gain 2-4 watts just by adjusting springs or changing brushes.

Determining whether your brushes need to be shaved is really quite simple. Look at the comm. and check for burn marks. However, you must ensure you are running proper gearing before investigating this area, as overgearing a motor has a tremendous effect on arcing/burning.

I traded my dyno for an oval car, and will never regret it. Dyno's will often run you into a trap, as they do not reproduce real world results. TonyV, adjusting the timing by shaving only one edge of a brush does not violate ROAR regulations at this time. However, they are in debate of this, but it will be difficult to pass because it is required for certain motors to perform correctly...and they can't force people to by X motor unless it is a handout race. I don't race other sanctions, so I can't speak on their rules.

There are plenty of great resources related to building motors.

Well, we can agree to disagree, I'm sure. I've decided to never argue with anyone anymore on these forums. I'm well versed with dynos and with motor building and I stick to my statement. There are things that do translate to the track from a dyno, some positive and some negative. It is a science, but the best dyno is a racetrack!

"I don't remember the technical details, but Big Jim had argued that shaving only one edge of the brushes would make the motor 'commutate' incorrectly. He recommended shaving both edges of the brushes only if you want to reduce amp draw and keep the motor cooler."

Does this affect rpm or torque though?