Brushless Motor Recommended Gearing Starting Points


Please Note: These gearings should be used as a general starting point with 540-size motors, but the motor & speed control operating temperatures should always be used to determine the final gearing that can be used for any given application.

Neither the motor or the speed control should be hotter than 160-175 degrees F after a five minute run. If either operating temperature gets above 160-175 degrees F, the vehicle's gearing should be lowered until both the speed control and the motor stay under this temperature.

Over-gearing the motor will result in excessive temperatures that can lead to internal damage of the motor, which can eventually damage the speed control also. This type of damage is not covered under the product's warranty.

Remember, the cooler the speed control runs, the better the performance & efficiency of the system.

Motor Turn Touring Car 2wd Buggy 2wd Truck 4wd Buggy 1/12 Scale** Oval**
3.5

10.5

Not Rec. Not Rec. Not Rec. 1.1" (28mm) 1.2" (30mm)
4.5 9.5 Not Rec. 13.0 12.0 1.2" (30mm) 1.3" (33mm)
5.5 8.5 11.0 12.5 11.0 1.3" (33mm) 1.4" (36mm)
6.5 7.5 10.0 11.5 10.0 1.4" (36mm) 1.5" (38mm)
7.5 7.0 9.5 11.0 9.5 1.5" (38mm) 1.6" (41mm)
8.5 6.5 9.0 10.5 9.0 1.6" (41mm) 1.7" (43mm)
10.5 5.5 8.0 9.5 8.0 2.0" (51mm) 2.6" (66mm)
13.5 4.5 7.0 8.5 7.0 2.3" (58mm) 2.9" (74mm)
17.5 3.5 6.0 7.5 6.0 2.6" (65mm) 3.2" (81mm)
21.5 3.4 5.0 6.5 5.0 2.8" (72mm) 3.5" (89mm)
25.5 3.3 4.5 7.0 4.5 3.1" (79mm) 3.8" (96mm)

The above gearings are given in Final Drive Ratio (FDR) form for standard-sized rubber tires. If you choose to use different sizes tires, use the formula below for rollout to determine the proper gearing for your tire's diameter. To calculate you FDR using standard-sized tires, first divide your vehicle's spur gear by the the pinion gear, then multiply that result by the internal drive ratio (found in the documentation that came with your vehicle) of the car.

Example: (72 spur / 21 pinion) x 2.5 internal drive ratio = 8.57 FDR

**The gearings for 1/12th Scale and Oval are given in rollout, which is determined by dividing the tire circumference (tire diameter x 3.14) by the spur and pinion gear ratio.

Example: (1.75" x 3.14) / (100 spur / 23 pinion) = 1.26 rollout

 

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