Basics of motor maintenance - RCCanada - Canada Radio Controlled Hobby Forum
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Old 09-05-2004, 11:04 AM   #1
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Basics of motor maintenance

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I found this on rc universe I believe it was a mag article at one point.
but its an informative enjoy.

There are some things involved with racing that people love to do, and some things people hate to do. Take building shocks; I hate building shocks. I don’t know why, I just hate doing it. Tweaking and working on motors however is something I love to do. I’m one of the few people that works on a motor after every single run, I enjoy it so much. When I work on my motor between rounds that does not mean it needs a complete rebuild with a commutator cut and new brushes, yet sometimes it does. After years of motor work, I’ve found some key points that will make your motor upkeep less of a chore and save you time. Here are some tips to help the new racer to the veteran driver; tips that can be applied to both modified and rebuildable stock motors.

Comm Cleaning

After the motor has cooled down from a run, remove the motor from the car and pull the brushes out of the hoods
by unlatching the springs.

The condition of the brushes can tell you a lot about how your motor is performing and also something about your gearing. If the brushes are a burnt-purple color, you’ve been overheating your motor and abusing it. Most times the cause for your motor to become overheated is that you have over-geared your motor. I’ll talk about gearing a little later.

Commutator inspection

Now that your brushes are out of the hoods, take a lookinside and check out the condition of the commutator. You should notice the
most wear around the slots in the comm itself. A comm cleaning stick is all you’ll need to clean the comm up. Slide a pinion on the output shaft of the motor, and turn the armature (arm) a few times with the cleaning stick inserted through the brush hood and pressed against the comm. When finished there may still be some burn marks around the slots. If they are severe enough, that’s when you’ll want to break out the lathe to retrue it. No lathe? Your local hobby store may have one and retrue your comm for a small fee. After the comm is cleaned, I flush everything out with motor spray.
Brush maintenance
You can get more runs out of a set of brushes than most people think, but you need to take care of them. For years I have used a fiberglass pen such as Trinity’s Comm Pen to clean the face of my brushes versus using the round part on a comm stick. The fiberglass pen actually gets between serrations on the face of a brush and gets the entire glaze off the brush, not just the stuff on the surface. If you put a hold in the brush face, inspect it to make sure it hasn’t been worn away. Also check the sides of the brush for wear and chipping. If need be spend a few bucks and pick up a new set.
Overall motor cleaning

When you remove the endbell to take the armature out of the can, be sure you don’t lose any of the shims that are on top of the arm. Set them aside and don’t lose them; you’ll need them when it comes time to put everything back together. Same thing goes for the shims on the bottom of the arm too.

With the arm out, take your motor spray and thoroughly spray out both the can and the endbell. Be careful to not get any motor spray on the brushes, it can actually soften them. Set the can aside to dry and hose down the armature with cleaner as well.

Using the shims you removed earlier, place them back on to the output shaft of the motor. If you really want to pick up an advantage on the competition, replace the brass shims with Teflon ones. The Teflon ones will spin with less friction making your motors operate more efficiently. You can use the brass shims to take up most of the gap, and use the Teflon ones where the shims would ride on a bearing or bushing. Place the motor’s timing ring back in and screw the endbell on. If you cut the arm, it’s recommended that you also replace the brush at the same time. I solder the brush leads onto the same tab where I solder my ESC wire to the motor.

By doing this, as much current as possible flows through the brush versus having to travel through the hood material. Slide the brushes into the hoods, and put the springs on. If you have rebuilt your motor more then five times and are still on the same set of springs, I would probably replace those as well as they will lose some of their tension over time.

Final Prep

Whether you had to do a complete rebuild or just a cleaning, there are some final tasks before you bolt your motor into your favorite ride.

Oil the bearings or bushings with highquality lube.
Hook your motor up to a 4-cell pack or other power supply and run it for a few minutes to break in the brushes. Stay under 5 volts though; you want to break the brushes in, not run them through a race simulation. No battery to break the motor in? No problem, just take the car out for a spin at a slow speed for 30 seconds to a minute—then you can give it full throttle.
If the brushes were discolored, drop a tooth or two on your pinion size, as you were most likely over-geared. You may want to adjust your settings on your ESC as well by upping the frequency or turning the current limiter down.
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Old 09-05-2004, 11:50 PM   #2
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One thing they don't tell you:

Put the endbell and can on the armature the wrong way (long side of the armature, where the pinion goes), so that the armature holds the endbell or can in the wrong direction (open side outward). Move the can and endbell by hand, if you can hear a grit during movement, there's dirt in your bearing. It has to be replaced or you could have a ceased bearing next run around. Bearing blasting isn't a good idea, as once there's grit in there, it's scored everything already. Blasting the dirt out, will always blast out shavings as well (a definate indication that that bearing is toast).

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