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  • SCX motors

    I wonder if I am the only one with this problem. It seems that from car to car with the same motor I get widely varying performance. They look alike and have the same identification stenciled on the can but one will be blazing fast while the next is only so-so. I treat them the same but even after a longer break in period the slower ones never seem to get anywhere near the power of the rest.

  • #2
    Have you tried moving the good motor to a car with a bad motor to see how it runs? the reason I ask this question is we set up a booth at the flea market each weekend and have people race our cars. We bring about 20 cars (porsche, aston martin, corvette and ferrari). There are times when we find one car faster than others, we do the cleaning to the slower cars, some times it helps some times it doesn't. if we move the faster motor to the slower car (and the slower motor to the faster car) the fast car is still fast, but the slower car is a little bit quicker as well.

    Now we do use digital, so it may be something in the chip causing this, but over the course of each weekend, we strive to get our cars to be competitive with each other, and one thing we do is move motors around. They do seem to change week to week, possibly due to different layouts each week....

    Ran

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    • #3
      Maybe voltage

      Hi , i have a 10 or so SCX Corvette's and have found the same issues. They all run differently at or below 12 volts,on a my home track .I found by adjusting the voltage to around 14 volts they come alive and are a more consistant to each other. But of coarse you need to have a varible power supply to do this. Its the only Manufactuer i have this issue with. Most of the other Manufactuers i have are fairly consistant accross their perfofmance level amongst the same car or model.Robert

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      • #4
        SCX motors are notoriously poor @ QC; they got better a few years ago, but they are still not consistent. They also get better w/ age. When competing in the SCX GT series, it was not unheard of for someone to go 5-6 motors to get a good one. I have about 15 SCX GT cars, all w/ RX-42B's & I have at least 35 motors. That said, there are only 3-4 cars I will try to compete w/, my best I bought from someone who placed very high in the series, a Corvette. I have changed wheels & crown gear several times, but the motor remains in my top 3, it has thousands of laps on it.

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        • #5
          Originally posted by Robert View Post
          Hi , i have a 10 or so SCX Corvette's and have found the same issues. They all run differently at or below 12 volts,on a my home track .I found by adjusting the voltage to around 14 volts they come alive and are a more consistant to each other. But of coarse you need to have a varible power supply to do this. Its the only Manufactuer i have this issue with. Most of the other Manufactuers i have are fairly consistant accross their perfofmance level amongst the same car or model.Robert
          Same here, Robert, and especially true of their older motors. They need voltage, or they'll be ridiculously inconsistent.

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          • #6
            One good thing about SCX motors is that they can be tweaked.

            Modlerbob,

            Have you tried running the slower ones in reverse, or tweaking the brush holders or checking brush tension.

            One quick fix to try is to remove the brushes (one at a time) and turn them 180 degrees and replace. Sometimes the brushes wear unevenly and "reversing" then changes the commutator timing.

            There is reams of information on how to tweak SCX motors, sure it is effort but sometimes the results are worth it , if only from a personal satisfaction point of view.

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            • #7
              Nice info Abarth Mike. I have 4 NASCARs. The one analog that I converted to digital is very fast and it really holds the track. The two that came with the set and the one I purchased come off in the corners. I believe its a magnet thing yet not sure how to manipulate the magnets other than turning them 180 degrees. One of the NASCARS sputters from time to time. Are there any other motor tweaks that you are willing to post to that could assist first time owners how to improve the performance of their cars?

              Comment


              • #8
                Hi,

                First place to start would be to surf for " Quick tuning SCX Nascar " The top result is the one you need. This does not address your magnet problem but is a great start.

                As for magnets. They are not all born equal! To test simply for comparative strength, without high tech equipment, remove each magnet and see how many small nails you can pick up with each magnet. This does not address the influence of height above the track but at least may explain why one or two cars are better than others. Next will be adjusting the height of the cars or the magnets to get them close to the same. Surf for " SCX nascar magnet adjustment "

                Motors as I said there is a lot of info just do some surfing. The stuttering maybe a dirty commutator/brushes or it could be as simple as the brass spring connection on that car not connecting properly. If dirty get some lighter fluid and a shot glass and run the motor in the lighter fluid. Don't have lighter fluid? Try a light dish detergent in some water, actually laundry detergent is stronger but lighter fluid is better. Don't forget of re-lubricate with a little drop of oil on the end of a pin.

                While looking for stuff for you I also learned something about SCX motors armature swap to 16D which i hadn't thought about and as I have a 16D armature in a box somewhere I might give that a try.

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                • #9
                  Arbarth Mike

                  I have an old rx42b motor that I was going to pitch, because it was losing power, and just not running as smooth as it once did. After reading your comments about tweaking it, I thought, what the heck. I'll tear it down and try a few and see what happens. If it doesn't work, I was gonna get rid of it anyway. I had never taken a motor apart before, and it really wasn't that hard.

                  Anyway, the first thing I noticed was the comm was really dirty. Cleaned that off, and then rotated the brushes and put it back together. I then checked it with my digital tach. It went from a lethargic 16,900 rpm to a fairly consistant 18,500! I then ran it backwards for about 45 minutes at 4 volts and and rechecked. It was amazing, it now runs a consistent 19,300 rpm!, and seems to run smoother to boot.

                  And to think, I was going to pitch it! Thanks for the tips!

                  Comment


                  • #10
                    Porky,

                    If you are going to use it, then it should run OK. There is a risk it will start to slow down a bit as the brushes wear even, but you can always tweak the holders to get that back. As you have a tach which I don't, you can see the exact results.

                    If you are simply having fun experimenting or doing what scientist would call theoretical physics you can get a few more RPM at the expense of a bit of torque by running the motor and putting a small grind stone onto the comm as it spins. I had one from somewhere but you could use a dremel stone? This does I believe two things. Evens out the comm stack pieces so improves balance and it makes the comm smaller so increases the air gap. If you look around you will find the article about this that I read.

                    It is messy and you'de have to take apart again to clean off all the fillings.

                    Some of the pleasures of life are simple.

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                    • #11
                      Arbath Mike

                      Your mention of using a sharpening stone on the comm, remimds me of another use for it, that I read about. The author of this particular post had a scx motor that was vibtrating badly. He hooked the motor up to a power supply and then lightly placed the stone against the stacks while the motor was running. He claims that it eliminated the vibration by shaving off the top of the offending stack and polished them. And the motor now runs with a smooth high pitched whine now, and that rpms are up as well. I might try this on a motor that I have. It also has a vibration when I run it, and as of now I don't use it because it is a rather low revving motor.

                      Also, I found another article where the author soldered in "shunts'' (I think that is what he called them) on a SCX slot car. He soldered a wire to the pos/neg sides of the motor, and to the brass rails on the chassis. I've heard of doing this to HO slot cars, but this was the first time I have seen it done on a 1/32 car.

                      He claims that it improved the responsiveness, and speed of the car. Although he offered no proof(as in lap times) that it did.

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                      • #12
                        Trouble shooting SCX motor that needs a push

                        I bot a used 1/43 SCX Ferrari 360 GTC and tried to run it on a Carrera Go 1/43 track w stock power supply. Problem: the car doesn't move, tried lifting the back wheels off the track- nothing. However if I lift and push the tires with a spare finger the motor then spins the wheels, i can lower the rear end onto the track and the car will cruise. Must hold plunger at full power with power boost engaged, if i release the power boost the car comes to a stop. Won't run again unless i lift and push the rear tires.
                        Already tried cleaning brushes and truing tires, also took magnet out, had same problem.

                        Any thoughts would be appreciated. I'm going to try running car backwards... I'll check back

                        thanks,
                        floridabones

                        Comment


                        • #13
                          My money is on one pole in the motor being bad. So it is toast and you'll need a new one.

                          However you might be lucky. If you are handy take the motor out and run it in lighter fluid in a shot glass, then re-oil the bushings and try again.

                          If that doesn't work. Well...

                          Don't have any lighter fluid or can't be bothered see next.

                          I think this is the correct size for a replacement if you can't find an SCX one!

                          http://www.electricdreams.com/Shop/b...r-p-11110.html

                          If you have two cars and you can't find an SCX direct replacement you'll have to buy two motors! Otherwise they will not be the same and cannot race against each other.
                          Last edited by Abarth Mike; 07-06-2014, 08:55 PM.

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                          • #14
                            Lighter Fluid

                            Abarth- what precautions do u use w lighter fluid? I suppose fully submersing motor and leads is adequate?

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                            • #15
                              Originally posted by Porky D View Post
                              Arbarth Mike

                              I have an old rx42b motor that I was going to pitch, because it was losing power, and just not running as smooth as it once did. After reading your comments about tweaking it, I thought, what the heck. I'll tear it down and try a few and see what happens. If it doesn't work, I was gonna get rid of it anyway. I had never taken a motor apart before, and it really wasn't that hard.

                              Anyway, the first thing I noticed was the comm was really dirty. Cleaned that off, and then rotated the brushes and put it back together. I then checked it with my digital tach. It went from a lethargic 16,900 rpm to a fairly consistant 18,500! I then ran it backwards for about 45 minutes at 4 volts and and rechecked. It was amazing, it now runs a consistent 19,300 rpm!, and seems to run smoother to boot.

                              And to think, I was going to pitch it! Thanks for the tips!
                              Porky - what type of dial do you use to attach to the shaft to trigger the tschometer?

                              Comment

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