How To Clean And Maintain A Brushed RC Motor

People who own RC cars know that they need to care for them. They will clean the tires, the suspension, and the various electrical components of the RC car.

However, the electric motor also needs to be regularly cleaned, but it can often be overlooked.

This mistake may come from the fact that brushless RC motors require virtually no maintenance and cleaning. However, brushed RC motors are not like that. Dust, dirt, and sand can get inside the motor because of its open can design, which spells trouble in the long run.

How to Clean a Brushed RC Motor?

The good news is that cleaning a brushed RC motor is a quick and easy process, and it doesn’t require any special skills to do.

1.Take the Motor Out of the RC Car

The first step is to take the motor out of the RC car. This is a fairly easy process, which may require a few basic tools that you probably already have lying around your home.

What you will need is, usually, a Phillips screwdriver and an Allen wrench.

After you have removed the motor from the RC car, remove the pinion gear as well.

Related post: How to Tell if an RC motor is Bad: A Straight Forward Guide

2.Spray the Brushed RC Motor With Compressed Air

Some people may choose to skip this step if they don’t have a can with compressed air, however, it makes for a more thorough cleaning.

Using a can with compressed air, clean the dust and dirt particles that have accumulated inside the motor’s body by spraying into the motor’s vent holes. (You can also use a keyboard duster.)

3.Spray the Brushed RC Motor With a Motor Cleaner

For this step, you will need a plastic container and a motor cleaner or an electrical contact cleaner as they will clean the motor and not leave any residue behind.

Hold the motor by the two cables (the flying leads) upside down over the container. 

Near where the cables are soldered to the terminals, you will see several small screw holes and vent holes.

Get your motor cleaner and spray it through the holes. A lot of dirt tends to accumulate around the fan openings as well, so don’t forget to spray it through the fan holes found on the sides of the motor’s body.

As you spray it, all the dirt and gunk will start coming out and dripping into the container.

Do that until the liquid dripping from the motor becomes clear.

4.Let the Brushed RC Motor Dry Thoroughly

After the cleaning process is complete, continue keeping the brushed RC motor in the upside-down position over the container for five to ten minutes to allow all the excess liquid to drip out.

After all of the motor cleaner has leaked out, it is time to let the motor dry. Take a soft piece of cloth and clean the outside of the motor. Then leave the motor in a place out of direct sunlight where it can air dry. The good thing is that the motor cleaner dries very quickly so it shouldn’t take too long.

Alternatively, some people prefer to speed up the drying process by using a hairdryer.

5.Lubricate the Brushed RC Motor

After your brushed RC motor has dried completely, it is time to lubricate it. You can use a standard 3-in-1 multi-purpose oil or an electric motor oiler.

Place a small oil globule on both sides of the motor shaft where the front and rear bushings are located. Then give the motor shaft a few turns in order to get the oil to spread out evenly around the shaft.

Using a soft cloth, clean the excess oil off. You do not want to have excess oil lying around as it can attract dirt, dust, and sand particles that can wear out the bushings.

6.Reinstall the Brushed RC Motor

Now that the brushed RC motor has been thoroughly cleaned and dried, you can put it back in the RC car.

Put the pinion gear back on the motor shaft and then slide the motor in the slot where the motor goes.

This is where the tricky part comes as you need to make sure the gear mesh is set correctly.

Usually, there will be two screws holding the brushed RC motor in place. One of the screw holes will be round, while the other will be elongated.

Running in wet conditions? Check out this post: Can A Brushed RC Motor get Wet?

Put the screw in the smaller hole—this is the static or passive screw that does not move. Then put the second screw in the wider hole and tighten it ever so slightly. You don’t want it to be too tight as you want to be able to move the motor in order to set up the gear mesh.

How to Clean a Rebuildable Brushed RC Motor?

Not all brushed motors are the same. Some brushed RC motors are non-rebuildable, which means that you cannot open them. 

However, if your brushed RC motor is rebuildable, then cleaning it will be a little different.

To disassemble and rebuild a brushed RC motor, you will need a Phillips screwdriver and an Allen wrench. (Optionally, you will also need a nut driver and a brush.)

1.Remove the End Bell of the Motor

The first step is to remove the brush housing off the motor.

Start by taking the springs off of the motor, then take the brushes out of the brush hoods and remove the springs.

After this, loosen up the screws on the side a bit. Make sure to mark down the timing of the motor before removing the end bell.

Remove the end bell and open the motor. This will give you access to the rotor, and you will be able to push the armature out of the can by pushing on the motor shaft.

2.Clean and Replace Necessary Parts

Usually, you may want to clean or even replace the bushings and the bearings found on the ends of the motor shaft.

The washers and the shims, on the other hand, are usually reusable, so do not discard them. Make sure to locate and remove them. They are very small and can be easily lost, so keep them in a container.

Pay attention to where the shims and washers are located as you want to make sure you reinstall them in the same position and sequence.

Do not try to disassemble the rotor, the stator, or the armature any further.

While your brushed RC motor is disassembled is also a good time to clean it following the above-mentioned steps and check if all the bearings are in good condition and move freely. In some instances, you may need to replace the bearings.

Replace the brushes if they have been worn out significantly and clean the brush hoods using a suitable brush. 

The general rule of thumb is to replace the brushes if they have lost about half of their length. That being said, people who are into racing and looking to get better performance do change their brushes more often.

3.Clean or Cut the Commutator

Comm stands for commutator. The commutator is the cylindrical part of the motor that is in direct contact with the brushes.

The best way to refresh a commutator is by using a lathe. However, if you do not have a lathe, you can go to your local hobby shop and have it cut there. Most hobby shops have the necessary tools and can do it for a small fee.

Related post: What Causes A Brushless RC Motor To Fail

If you are not too serious about racing, cutting the comm may not really be worth it. However, keeping the commutator clean is still highly recommended.

There are also a few other ways you can clean the commutator.

A comm stick can help, but it cannot substitute a proper lathe cut since commutators will slowly erode and wear out at the area where they make contact with the brushes.

A comm stick (or a comm cleaner) is an abrasive stick used to clean and refresh the commutator. All you need to do is put the commutator stick inside the brush hood and run the motor for a few seconds.

Sanding paper can also be used to clean the commutator. However, this should be done with extra care as not doing it properly can cause the commutator to become uneven.

To make sure the sanding is even, you will need to use a drill or a rotary tool to which you stick the motor’s shaft. Wrap the sandpaper around the commutator and spin the commutator using the rotary tool at very low speeds. Hold the sandpaper and apply light pressure until the commutator has been thoroughly cleaned.

Sand following the same path, the commutator turns and not against it.

There are also commutator cleaning sprays that some people may prefer to use instead. A contact cleaner and a soft toothbrush can also be used on the commutator to clean the dust and dirt buildups.

Cutting the commutator will ultimately improve the longevity and performance of the motor. However, commutators are not replaceable or repairable, and even though only a tiny layer of them is stripped away, they do also wear out naturally. Eventually, the commutator will become too thin to work properly. At this point, the motor or the armature should be replaced.

How often you will need to cut the commutator will vary from motor to motor and depending on where and how you are using your RC vehicle. Generally speaking, you may need to cut the commutator every 5 to 30 runs.

4.Thoroughly Clean and Rebuild the Motor

Before you close the motor, you need to clean it thoroughly. Pay close attention to the openings between the commutator segments. Dust, dirt, and debris can get stuck in there, which should be cleaned.

After everything has been inspected and the necessary maintenance and cleaning have been carried out, it is time to rebuild the motor.

Reinstall the bearings and the shims, ensuring they are placed in the same order and place there originally were. Gently place the armature inside the can. It is highly magnetized so expect it to suddenly be pulled inside by the magnetic force.

Check the rotation direction and the motor’s timing to ensure the motor is good to go.

How Often Do You Have to Clean a Brushed RC Motor?

How often the brushed RC motor should be cleaned will depend on the terrain, the conditions, and how much you are using your RC car.

Generally speaking, on tarmac and dry grass, you should clean your brushed RC motor every 5 to 15 runs, while on dirt, sand, wet, and muddy terrain, you may need to clean the brushed RC motor every 1 to 3 runs.

Make sure to always check your user’s manual as there should be information about how often your brushed RC motor should be cleaned.

What Happens if You Don’t Clean a Brushed RC Motor?

With time and use, dust, sand, and dirt accumulate inside the brushed RC motor, causing it to gradually lose performance and eventually stop working.

It can also cause the motor to run hotter, increasing the risk of overheating and breaking.

That being said, in most cases, brushed RC motors will simply stop working. Often people think their RC motor has burned out, and they replace it without even knowing that it may have stopped working simply because it has gummed up.

Common Mistakes Cleaning Brushed RC Motors

There are some common mistakes people make while cleaning their brushed RC motors, which I believe should be addressed.

Can You Clean a Brushed RC Motor With WD-40?

Do not use WD-40 when cleaning your RC motor. As the WD-40 evaporates, it will leave a light oil film—something that you do not want inside the brushed RC motor.

WD-40 can be used to protect some tools, clean moving parts, and remove dust and dirt, but it should also be cleaned afterward. And if you spray it inside the motor, you will not be able to clean it properly. This can either destroy the motor or cause it to lose performance.

If you have already used a WD-40, try cleaning it using the steps mentioned above using the motor cleaner. (You may have to repeat this step two or three times to ensure quality cleaning.) However, it is very likely that the motor will simply not work properly and should be replaced with a new one.

WD-40 is also not a lubricant either, so make sure you use proper lubricating oil for the motor shaft.

The lubricant-like qualities of the WD-40 come from the dirt and gunk it is dissolving and not from the WD-40 itself. The WD-40 will displace what is left of the already existing lubricant around the motor shaft, too. 

It may provide some low levels of lubrication for a short while, but it can make things worse as it dries and evaporates.

Can You Clean a Brushed RC Motor With a Carb or Brake Cleaner?

If you have a car or a motorcycle, you will likely have a carburetor or a brake cleaner. Both agents are used to clean either the carburetor or various other parts of the vehicle. As a result, many people may be tempted to use them for cleaning their brushed RC motor.

You should not use a brake or carb cleaner on your brushed RC motor as they can be very aggressive, depending on their content. Some of them can even melt the plastic parts of the motor.

Does Cleaning a Brushed RC Motor Too Often Damage It?

If the right cleaning and maintenance procedure and methodology are followed, there should be no reason for the brushed RC motor to get damaged.

You can clean a brushed RC motor as often as you like. Many owners even clean their brushed RC motors after every run without that negatively impacting the motor’s longevity or performance. 

In fact, you should clean your brushed motor often in order to prevent dirt damage and keep it in good working condition.

As long as the right cleaning and maintenance steps are followed, you should not cause any damage to the motor—to the contrary, it is more likely that you will extend the motor’s life.

How to Lubricate the Brushed RC Motor?

When lubricating the motor, make sure only to place one drop of oil near the motor shaft on each side of the motor. This is more than enough.

Oil only the bushings on either side of the motor and don’t place oil on the bearings or any other parts inside or outside the motor. Putting oil inside the motor can attract dust and dirt, which can damage the motor.

If you want to lubricate the commutator, make sure to use comm drops only.

How to Break in a Brushed RC Motor

It is considered good practice to break in a new brushed RC motor. Breaking in a brushed RC motor is not mandatory, but it can give the motor a slight boost in performance and improve the longevity of the brushes and the commutator.

Usually, breaking in is more important to brushed motors with hand-wound armatures than to motors with machine-wound armatures.

The break-in process is needed because it allows the brushes and the commutator to sit properly.

Generally speaking, there are two ways to break in a brushed RC motor, a wet method, and a dry method.

Make sure to break in your motor using the methods recommended in your user’s manual, as this will ensure the best longevity and performance for your particular motor.

Brushed RC Motor Water Break-in Method

One of the old-school methods of breaking in a brushed RC motor is the so-called water method, where the RC motor is run while submerged underwater.

Most racers really like the water break-in method. The water break-in method is usually easier on the commutator and the brushes, and it also allows the motor to run at cooler temperatures.

During the water break-in method, the motor is submerged underwater (usually distilled water is used) and run on no more than 3 Volts. This can be achieved by hooking it up to 2 D-sized batteries, for example,

You should use a fairly deep container as water may spill out while the motor runs.

The motor is left to run in the water for 1 to 10 minutes (sometimes even more), depending on how hard the brushes are. 

The brushes’ condition should be monitored every few minutes if you are unsure of the right break-in period, as leaving your motor to break-in for too long can significantly wear out the brushes.

As time goes on, the water will darken, which is normal as this is caused by the carbon from the brushes and the dirt from the motor.

After the water break-in process is done, the motor should be thoroughly dried, sprayed with motor cleaner, and the bushings lubricated. You don’t want to let the water sit inside the motor, as this can lead to corrosion and rusting.

Usually, the water method for breaking in a brushed RC car is used to get the most performance out of the motor, but the downside is that the motor’s life will be reduced.

Related post: Want to Go Further? How to Improve the Range of Your RC Car

In addition to that, most brushed RC motor manufacturers do not recommend using the water method to break in their brushed motors. The water method of breaking in a brushed RC motor can, in fact, do more harm than good in the long turn. Water is corrosive and abrasive and can lead to increased wear and tear of the motor.

Dry Brushed RC Motor Break-In

The best (and safest) way to break in a new brushed RC motor is by running it on low Voltage (usually 3 Volts) for one to three minutes.

This means that you can properly break in a motor without necessarily using any specialized equipment. Just go easy on the first one or two battery packs. Have the throttle trim set at no more than 1/4. Ideally, you want to use the RC car in warmer weather and go very light on the throttle. Make sure to drive it both forward and backward.

Other ways to break in the motor are by lifting the driving wheels off the ground, by removing the pinion gear, so it doesn’t make contact with the spur gear, or by simply turning the RC car upside down.

After the break-in process is finished, make sure to clean the motor by following the steps mentioned earlier in this article.

With the dry method of breaking in a brushed RC motor, you will usually get a good motor’s life, but you may not necessarily get the best performance out of the motor.

How Long Do Brushed RC Motors Last?

Brushed motors will eventually burn out and stop working. Proper maintenance and cleaning will allow you to get the best performance and longevity out of a brushed RC motor.

Most brushed RC motors last between 2 to 12 weeks. Some brushed RC motors can last up to 3 years if used on tarmac, concrete, or asphalt, are well maintained, and not used aggressively. Brushed RC motors used on dirt, muddy and wet terrain can last between 2 to 8 weeks.

The problem with brushed RC motors has always been that they require more rigorous and frequent maintenance and cleaning (compared to brushless motors). The motor’s can is open, allowing dirt, dust, and sand to easily enter the motor’s internal parts. As the dirt and dust accumulate, the motor will wear out faster.

Depending on where and how a brushed RC motor is used, you can easily go through a few of them in a month or use a single motor for more than a year. Because of that, often switching to a brushless motor may end up being cheaper in the long run.

Overall it is hard to say how long a brushed RC motor will last as there are many variables. However, a few telltale signs will indicate if a motor is near the end of its life.

Check how much copper is left on the commutator. Commutators usually will continuously wear out the more they are used. Eventually, they come off and fall, rendering the motor useless. In most cases, commutators have some minimum diameter ranges. Most people will avoid letting their commutator go below 0.270″ in diameter.

The other thing to look for is performance. Over time the motor’s performance will start to decline slowly. If there is no improvement in the motor’s performance after proper cleaning and maintenance, the motor will likely be at the end of its life.

Paul Good

This awesome hobby has something for everyone, whether you like to build your RC from scratch and keep modifying till you've got it to just how you want it, to track racing. You might be out with a boat, or perfecting your skills with a plane. Are you taking some cool pics with your drone? I'm sure my site will help you on your journey.

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