How To: Get the most out of your brushless motor!

by Aaron Waldron

How to understand brushless timing

Brushless motors have completely taken over racing, and pretty much everyone has switched to brushless. Most racers are hitting tracks with sensored 17.5 brushless setups, but  unlike their brushed 27-turn “stock” predecessors, these motors allow you to change the motor’s timing. The only problem is that motor timing is still a bit of a mystery to most racers, and in this case, knowledge is power. Here’s the scoop on how and when to adjust timing, so you can get the most possible power out of your brushless motor.

WHAT TIMING DOES

Brushless motor timing is the relationship between the motor’s sensors and the phases of the stator. Brushless motors react to increases and decreases in timing the same way as brushed motors, but most are a little less sensitive to changes. Increasing timing increases rpm and motor temps but decreases torque, efficiency and run time. Decreasing timing does, as expected, just the opposite. Timing changes are similar to gearing changes but are far more subtle.

KEY TIMING TERMS

• EFFICIENCY: measurement of how much energy Is transformed into usable power
• RPM: short for rotations per minute; a measurement of speed
• TORQUE: measurement of force, specifically rotational power.

HOW TIMING IS ADJUSTED

There are two ways to adjust timing depending on the type of brushless system you’re using. Many speed controls feature software that offers the option of changing the motor’s timing, and you can also physically adjust the timing on the motor. Typically, you loosen, but don’t remove, three screws on the endbell and rotate the endbell counter clockwise to align timing marks on the endbell and can. Some systems allow you to adjust timing via the controller as well as on the motor.

WHEN TO CHANGE TIMING

The easiest way to know if you need to change timing is to use a temp gun. To help get an accurate temp reading, add a small piece of black tape or even black paint to your brushless motor. The first thing you want to check is that after a full-length run (not two minutes) the motor is below 180 degrees F. This is the threshold for most motors. At 180 degrees and above, most motors will lose power and potentially fail. Even if a motor doesn’t fail, excessive heat permanently causes magnets to lose their strength. If your motor is at or near 180 degrees F, try reducing motor timing, and recheck it. If that doesn’t work, it will be necessary to change gearing with a smaller pinion.

After you’ve determined that you aren’t running too hot, make sure you aren’t running too cool. If, after a full-length run, your motor is at less than 140 degrees F, the motor is probably not making its maximum power. The “sweet spot” is usually at about 160 degrees F. Try to increase timing before you make a gearing change.

Another way to use timing is when a single-tooth pinion change is too much of a change. Motor timing is usually the perfect way to split the difference.

If you feel your motor is fading near the end of a run, regardless of the motor’s temp lower the timing. This is typical during the hot summer months. Generally, when outside temps are in the 90s and above, try lower timing settings.

In the same way that many professional off-road racers use gearing to tune for available traction (you knew that, right?), motor timing can be used to help on a slick track. Instead of going up a pinion size, first try to increase timing. This will reduce the low-end power and decrease the tendency of the tires to break traction.