The motor powers the car. Each model trades off speed, torque and battery draw, favouring acceleration or top speed. PRO chassis (MA, MS, ME) take double-shaft motors and all others single-shaft. Some motors are not allowed in Junior and other classes, so check class legality before buying.
For how each kind of part is used and tuned, see Tamiya Hong Kong's Mini 4WD setting guide (in Chinese).
32 parts
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