Some say I have an 'unique' view on how power is developed and controlled in RC racing. Others wonder if I think at all! But let's explore how to use gearing and timing to help your racing anyway!
I consider timing and gearing to be like two dance partners. When the two dancers are in sync, the result is beautiful performance. The same is true when getting the most usable power from your brushless motor, especially when the racing surface is slippery and you have a lot of power in the car from low wind motors. Big power brushless motors become unwieldy and can easily upset a car's handling when accelerating from low speeds. A well setup car suffers when the motor does not sync with the driver's desire to have smooth power output!
There are several tools we can use, including other settings in the ESC, but I thought we should look at the interaction between motor gearing and its timing setting. I anticipate you are happy with how you have your motor geared and where the timing is set; if not, see other blog entries on how to arrive at that point.
- Always run a fan.
The track you are on has more/longer straights and you would like more top end speed. You put a pinion on with more teeth, which increases speed, so far so good. What about the battery having enough energy for race length? Is motor power controllable? Is motor temp within normal limits (less than 150 degrees)? In this case, we would also reduce the motor timing a bit, a 5 degree reduction is a good start, and see if have made the performance better. If motor and ESC temp is still reasonable, the motor still feels easy to manage, then lets reduce 5 more degrees (making a total reduction of 10) and test again.
Maybe you have tight/compact corner and you want more torque or the straight is short and you are running past the corners. Reduce the pinion gear teeth count, torque increases, better launch happens. Again, do you have fine motor control? Still have enough top end to be competitive? OK, let's try adding 5 degrees of timing (and eventually a total of 10 degrees) and see how the motor feels, watching the motor and ESC temp to keep them reasonable.
Record these findings in your race log. More data, better results, as you learn how your motor performs.
NOTE: There was an error in my original discussion where what I typed is not what I meant! My intention was to say if you increase the number of teeth on the pinion, you should reduce timing; what I said was ambiguous. Alphie Adams pointed it out to me, fortunately before too many read the article, and the text is now corrected.