Motor Maintenance

Maintenance Tips for Faster Electric RC Motors
With the proper maintenance, your stock or modified motors will stay in peak condition with maximum power, speed, and rpms.

First maintenance tip is to use a high quality motor spray to clean out the dirt and carbon deposits. It is best to do this after every run. Put a drop of oil on each bushing or bearing.

Warning: Do not use WD-40 or brake fluid, these may damage your motor.

Brushes
For peak performance, replace motor brushes after 20 runs (stock motor) or 10 runs (modified motor). Also, if the tip of the brush that touches the commutator has turned purple, it is time for a replacement.

Commutator
Before reinstalling new brushes, it is good to have the commutator "trued" by a diamond bit lathe. This will ensure that the commutator is perfectly round and smooth.

Springs
Over time, the brush springs will lose their tension. You can check this with a spring tension checker device. But if you can afford it, change to brand new springs the same time you change the brushes.

Magnets
Time and excess heat will cause the magnets of a motor to weaken. This will drastically reduce a motor's power. There are devices called magnet zappers that try to restore a magnet's strength, but this is usually temporary. Once you feel the magnets have weakened, it is best to buy a new can (with magnets) or buy a new motor.

Summary: The reality is that a motor's power decreases every time it is used. The only way to get back the original power is thru proper and frequent maintenance.

STOCK MOTOR MAINTENANCE & TIPS from Fantom Racing.

MAINTENANCE & TIPS
The following are some tips and suggestions for keeping your stock motors running wicked fast.

When building your motor, always make sure to properly place the shims, on the armature shaft, so that the armature "floats" in the magnetic field, with about .002" to .005" of end play.

We suggest using a brush hood alignment tool, to make sure the hoods are lined up exactly 180� opposite each other. This can make a huge difference in performance.

Never over tighten the endbell screws. If your timing ring is bent, you are over tightening it. It is always best to keep it as flat as possible.

Make sure to always lube your motor after every run. Be careful not to over lube, though, because too much oil will work its' way on to the commutator and effect performance. Just one drop per run, on each bushing, is usually plenty.

Comm drops are recommended before each run. We recommend two drops per run, directly on the comm.

On the second and third run, before running, we suggest using motor spray to increase performance. We recommend spraying out your motor thoroughly, without taking the brushes or springs off. Your brushes have been “seated” at this point, and that is something you don’t want to disturb. An air compressor or air tank is good to use after spraying your motor out. This will remove any excess residue remaining from the motor spray. Always remember to re-lube your motor after this process.

For maximum performance, cutting your comm after the third run is the average interval, but changing the brushes at this point may not always be necessary. We recommend checking for serrations on the face of the brushes and/or discoloration. The rule of thumb is if the brushes are worn more than a third of their original length, or are discolored, they need to be changed. When a brush gets over heated and discolored, it loses some of its’ lubrication properties, which can cause severe damage to the commutator, in a hurry. You can also refer to our brushes page for more information on our brushes. If, after the third run, there are still serrations showing (even the slightest amount), we suggest only cleaning the face of the brushes with a brush cleaning stick. Many times you can find some amazing power at this stage, because now what you have is a good set of brushes that have been broken in to form fit your fresh cut commutator. Normally we’ve found that you can get two good runs out of your motor at this point, before more service is needed.
MOST COMMON MISTAKES

The biggest mistake we see is that people are neglecting to cut their commutators, causing the commutator to wear improperly or excessively (out of spec). It doesn’t take much to get to this point, and sometimes it is not even visible to the naked eye. This can include out-of-roundness, from warping, due to the high heat generated in this area and/or a concave wearing pattern around the circumference of the commutator, from the continuous wear of the brushes against the commutator. Simply cleaning the commutator with a comm cleaning stick is not enough. What happens is when the commutator becomes “out of spec”, the brushes don’t have a nice smooth surface to make contact with, which causes excess arching, from the current flowing between the brushes and commutator. This begins to deteriorate the commutator and brush surfaces, and it becomes a snowball effect. The more the commutator wears, the more the brushes bounce, leading to more and more arching, which can destroy a motor very quickly. Keeping the commutator flat and round is the key. Cutting the comm in just small amounts will make it last much longer than never cutting it at all.

Over gearing is another big mistake that we see all the time. This is a motor builder’s worst nightmare, because it can make even a really good motor look bad. Over gearing can literally ruin a motor in one run. Technically what happens is the motor gets overloaded beyond its’ designed capabilities, causing all sorts of nasty things to happen, including over heating and melting the coating off the wire, causing the motor to short out, and rendering it useless. Over gearing can also cause major arching of the brushes and commutator, which has side effects as discussed above. Over heating of the magnets is also common, which weakens them significantly. A common misconception is that the bigger the gear you put on, the faster the car will go, but unfortunately it is not that simple. Every motor has its’ “sweet” spot for gearing, and even two of the same kind of motor may need to be geared slightly different. Because there are so many variables, it would be nearly impossible for us to tell you what gearing to use for your application. Our suggestion is that you refer to your car’s instruction manual first. Most manuals include suggestions on gearing. Once you have a starting point, you can then go up or down from there, in one tooth increments. To be safe, it’s always a good idea to start with a smaller pinion gear than recommended, and work your way up. Experiment with the gearing until you achieve a combination of good acceleration out of the corners and good top end speed on the straightaway. Take your time with this, and you will be rewarded with faster lap times, and a longer lasting motor.

Most people put too much emphasis on the motor and batteries, when there is much more to going fast than just those two things. Probably because it’s the easiest thing to blame, but the ironic thing about it is that the motor and batteries, 9 times out of 10, have the least to do with slow lap times. We could write a book on all the potential variables, the least of which would include car set-up, tires, speed control, and gearing… just to scratch the surface. Last, but definitely not least…practice!

Not taking the time to clean and re-lube your motor properly, or using poor performing brushes on rebuilds can also cause less than satisfactory performance.