I just got an trail truck. Do I need to break in the motor? The old-timer at the hobby store said that I should dip it in water.
You can go directly to the trail without worrying about break-in. If you want to get the longest possible life from your motor, you can run the car on flat ground for 20 minutes or so before getting into heavier terrain that will load the motor. The objective of motor break-in is to allow the motor’s brushes to seat themselves against the commutator. The water-dip method that your guy at the hobby store mentioned is an old-school technique; basically, you would run the motor underwater at low voltage for a few minutes to speed up brush wear. It did (and does) work, but it’s not worth the trouble of disassembling your RTR.
The brushes will seat themselves under normal use, and since trail trucks are geared for torque instead of speed, they’re pretty easy on the motor. What kills motors is excessive load and excessive heat (the former usually causes the latter). Avoid conditions that place continual strain on the motor, such as tall grass and soft sand. The key word there is “continual.” Stressing the motor to get through a section of grass or sand or a steep climb won’t hurt anything. But if you run through tall grass for an entire battery pack, that’s the type of abuse that can dramatically shorten motor life. No matter how gentle you are on your gear, any brushed motor will eventually wear out. When you’re ready for a replacement, consider upgrading to a motor with replaceable brushes or go brushless.
For maximum motor life, avoid overstraining the power system.
The brushes contact the commutator to energize the wire wrapped around the armature. As the commutator spins, the brushes wear against it. The performance of a brushed motor will improve as the brushes seat themselves against the commutator.