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Cleaning the brushes in the motors?

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  • Cleaning the brushes in the motors?

    I have 3 NSR cars that I think have dirty brushes. I can see or hear arching, plus some very uneven acceleration. I don't think it would be a good idea to open the case of these motors, since they are just held by two little tabs. All 3 motors are the Shark 25 and are among the first cars I bought and I didn't break them in right... didn't know any better. I have some Power Booster braids and commutators. Is it worth trying to clean the brushes or just buy new motors?

    Since I'm on the subject, what is a proper break-in procedure for these motors? I have heard differing ideas.
    Last edited by Bal r 14; September 3, 2021, 09:52 AM.

  • #2
    I used to do brush cleaning on my RC car motors, and all I did was spray aerosol automotive brake cleaner into the motor housing and then blow out the excess. For heavy use RC motors, the brake cleaner fluid would drain from the motor quite dirty but it took a lot of heavy use to require brush cleaning. Not sure how much of a factor this is for slot cars. Brake cleaner is hard on paint and finishes, so best to remove the motor for this spray cleaning.

    You can buy motor cleaning sprays from RC hobby shops.....but I thinks the same as automotive brake cleaner.
    Toronto, Ontario


    • #3
      try wd 40 and run it a minute
      Matt B
      So. In


      • #4
        Nothing works as good as the old alcohol dip on 1/32nd motors. Great for break-in, too.


        • #5
          I spray contact cleaner into the motor & run it.......Harry & the guys showed me to just
          dump into a cup of alcohol.........
          I used to load the motor up with lighter fluid & run it............'till I had a very realistic fire going down the back straightaway
          Dave J
          Millstadt, Illinois


          • #6
            Just flush the motor out with what ever cleaner you have handy
            WD 40 and a couple of shots of power from a 9v battery would clean it out (if it’s dirty)
            When the wife’s not looking hold it under running water in the sink and give it a couple of shots with the 9v and then flush with alcohol and dry just make sure it’s dry before you power it up again
            Ive only used lighter fluid on 1/25 drag cars and like Brew I’ve had a car on fire
            Peterborough Ont


            • #7
              Voodoo Juice on the comm works well.


              • Pappy
                Pappy commented
                Editing a comment
                In the short term Voodoo works but over the long haul it tends to gum up a motor. I use to use it on 1/24 scale motors. A can of electrical contact cleaner spray is what I use. If you dump your motor in something while running it don't do it for more than a few seconds, sometimes depending on the motor brushes it will eat them completely up in a very short period of time. Or as Mike said, just get a new motor. If you like a 25,000 rpm motor give the 25,000 rpm Predator a try. Very smooth power curve.

              • Bal r 14
                Bal r 14 commented
                Editing a comment
                I am using the Predator 25k motor in the Matra/Simca. I like it. As you say, smooth.

            • #8
              Just replace the motor, you are already having issues with them, the brushes are not very big on them you may have already worn them out you said they were older motors.
              Clover Leaf Racing 7746 Clyde Road Fenton MI 48430 U.S.A. 313-473-SLOT
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              • Bal r 14
                Bal r 14 commented
                Editing a comment
                Older is a relative term. Probably 4 months and less than 2 hours of use. But I didn't of breaking them in at the time. I haven't used a small brushed motor in many years, so I just plain forgot.

            • #9
              Do yourself a favour, and , do not use Voodoo drops on your comm. (or any other type of oil !!),......and, try the following before shelling out for a new motor.

              As mentioned above, with the motor running at a couple of volts (in the rotation it normally runs in), give the comm a shot or two of contact cleaner,......dry, and give the can end bushing a tiny drop of oil.

              If you do not have any contact cleaner, drop the motor into a glass of water, a run for a minute or so in he normal direction of travel.........dry, oil the can bushing.

              The likely reason for your issue is that some of the worn brush material gets into and fills the slots between the comm plates,...this causes shorting and overall poor performance.......the contact cleaner/water will likely dislodge the gunk from the comm slots, and you will be good to go.

              Chris Walker


              • #10
                I have a bottle of Kinwald Formula 96 (25 years old) brush worked great if you keep the comm scrupulously clean which was a pain for basic club r/c racing hence why the bottle is still 90% full.
                I've raced slot cars for 6 years and occasionally put a few drops on braid but wouldn't put it anywhere near the inside of a motor.
                Kevan - Isle of Man
                Life is like a box of Slot cars...🚓🚗🚚🚜


                • #11
                  It says right on the bottle of Voodoo juice (label is somewhat faded) that it can be used to break in a motor (then flush) and drop on the comm before a race. With every new motor I get, I run it for 4 minutes in a 80/20 mix of alcohol/water. Works well for me.


                  • chrisguyw
                    chrisguyw commented
                    Editing a comment
                    Voodoo drops (oil) are commonly used by drag racers who disassemble/clean and true comms with almost every pass............the "oil", while it does lubricate the comm to an extent, does soften the carbon brushes and the "debris" tends to accumulate in the comm slots.
                    You will not find any experienced commercial track racer using them for anything other than drag racing, as it ruins comms/brushes.

                    Most labels do have a bit of a Marketing slant to them.

                  • 4424ever
                    4424ever commented
                    Editing a comment
                    Thanks Chris it was all the rage when it came out until it’s prolonged use was realized
                    Think there’s a bottle of it around here I won’t use even on my drag cars
                    Last edited by 4424ever; September 3, 2021, 08:29 PM.

                • #12
                  I guess I will give alcohol a try.


                  • #13
                    With tired motors that sparking can be seen through the end-bell, I've dunked them in lukewarm water and run them at about 6v for a couple of minutes and revived them and sometimes the water can be seen to turn a bit grey.
                    CHCH NZ


                    • #14
                      Doesn't running a motor in water cause rusting?


                      • Wobble
                        Wobble commented
                        Editing a comment
                        Not if you leave it on the widow sill in the sun for a couple of hours or oil it and run it for a few minutes until it starts to warm. The warmth and air circulating running it causes, dries it out pretty quickly.

                      • Pappy
                        Pappy commented
                        Editing a comment
                        I knew a guy who would go to the utility tub between heats and run cold water over his motor to cool it down. Shake it off and run it again. Never did hurt it, he was one of the fastest guys at the track.

                      • Kevan
                        Kevan commented
                        Editing a comment
                        Only if you leave it wet.

                    • #15
                      The problem with most 1/32nd motors is that as the brushes break in it is possible that dust from the brushes will get caught in the commutator slots and short out the commutator. If the short is not total the motor will slow down and use more power than it should. If the short is total the motor will run very slowly or not at all and will draw a great deal of power, get very hot and possibly burn out. These motors will run at least slightly better once the brushes are broken in. You can break in the brushes by simply running the motor in a car and driving it normally around the track. I prefer to run motors in on the bench at about 6 volts for 30 minutes. After the run-in is done I flush out the endbell with electrical contact cleaner. I do not recommend using anything that contains oil, that includes WD-40. You should also avoid using any sort of magic commutator drops, those are likely to cause a shorted commutator. You can reduce the break-in time and avoid getting dust in the commutator slots if you do a break-in in a liquid. Water with a little dishwashing liquid in it works well. When the break in is done flush out the motor with alcohol. You can also do the break-in using alcohol, but be careful to shut off the power before you remove the motor from any flammable liquid or you might start a fire. Do not leave a motor running in a liquid for too long or you will wear out the brushes.
                      It is nice to have a power supply with built in volt and amp meters. If the motor has a shorted commutator the high amp reading will make that obvious. if you are using a set type power supply those do not have enough amps to burn up a motor, a power supply that can deliver 5 or more amps could burn up a shorted motor very quickly.
                      If a motor has a shorted commutator sometimes you can remove the dust by spraying contact cleaner directly on the commutator while the motor is running at 6 volts. If that does not work you would have to take the motor apart and scrape out the slots using a bit of plastic packaging material. Something like a X-acto knife might scratch up the commutator.