This guidelines provided by Extreem RC CARs
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Although brushless motors are touted as being maintenance-free, we often overlook the fact that this is more of a comparison to their brushed counterparts rather than a statement in itself. Just like any part of your car, truck, or mini, brushless motors need a little bit of tender loving care to continue operating at their highest level. Sure, there are no commutators to true or brushes to replace, but they can accumulate dirt like anything else, can have bearings go bad, and sloppy wiring or broken wires can lead to performance problems or even damage to the units themselves. Being able to install a brushless motor and forget about it is a great convenience, but if you devote a little bit of your wrenching time to maintaining your brushless you'll be rewarded with a happy motor that continues to perform well for a very long time.
General Maintenance
Start With a Cleaning • When you sit down between race days to work on your car, there are a few simple tasks you should always perform on your brushless motor. First and foremost, you want to make sure the motor is clean, since dirt and grime can hurt a brushless motor just as much as it can hurt a brushed motor. Use a brush or a cleaning rag to wipe down the surface of the motor, taking care to inspect it for any obvious signs of damage.
Check the Feel • Since brushless motors don't provide a ton of resistance when you spin them, it is usually very easy to see if something is causing your motor to seize up. With the motor cleaned and out of the car, spin the armature to feel for any grittiness or "notchy" behavior. If you sense that it is not spinning as freely as it should, you should probably disassemble the motor and clean it out.
Inspect the Wiring • Your brushless motor has quite a few wires coming out of it, and each and every one of them is very important. Hopefully your wiring is adequately protected from moving parts and outside influences, but even if so, accidents can happen and wires can become torn or frayed. Make sure that none of the wires are exposed, and that none are in danger of contacting one another. If the insulation on any wire has been torn or the inside exposed, use electrical tape to re-insulate it.
Lubricate • The main point of contact between your motor and the outside world is its partially exposed bearing, and you want it to spin as freely as possible. After cleaning the motor, be sure to add a drop or two of thin bearing lubricant to the bearing. The lube will keep it spinning freely and help to ward off debris.
DISASSEMBLY
From time to time, or if you ever notice a problem, you should disassemble your brushless motor to inspect and clean it. Don't be afraid; the process is really quite simple, and much more so than a brushed motor.
1.Removal
Remove your motor from the vehicle, and unsolder the wires and disconnect the wiring harness if possible. While you're at it, clean the area around the motor mount and anywhere else that dirt and debris may collect.
2.Disassemble
Most brushless motors are quick and easy to disassemble, with a few hex-head screws on either the front or rear of the case, or possibly both. Take your motor apart and lay the parts out in front of you.
3.Clean
Just like a brushed motor, dirt and grime can build up inside the can of a brushless motor, so clean both the rotating parts and the can itself. Spray the can with motor spray and allow it to dry before reassembly. Wipe down the armature as well.
4.Re-Lube
Since you just sprayed down the can and the bearings along with it, you'll need to re-lubricate them. Put a few drops of thin bearing lubricant in each bearing. If after spraying and re-lubing a bearing it still feels gritty or seizes up, it needs to be replaced before running again.
5. Bearing replacement
Should you need to replace a bearing, first consult with your motor's manufacturer to make sure that you have the right size in mind. Try to find a replacement bearing with a metal shield, as this will resist damage and debris more effectively than a rubber or Teflon shield. If you have one, use a bearing pusher to pop the bearing out of the can, and then push the replacement back into place. Add a drop or two of bearing lube to the new bearing as well.
6.Reassembly and Installation
You're all done! Put your motor back together and then reinstall it in your vehicle, as good as new.
It's Not So Bad!
There, that wasn't so bad, was it? Compared to brushed motors, maintaining a brushless system is as easy as can be. For these few minutes spent, you will have a motor system that continues to be effective and trouble-free, and hopefully one that lasts for a long time to come. There is still no such thing as a maintenance-free RC motor, but brushless systems come awfully close.
