# Motor Brush Adjustment



## HOcar (May 12, 2017)

I'm looking for some advice on how to adjust motor brushes. I have read people recommending to tighten a 1/4 turn at a time and some saying to measure current draw. What adjustment method do you use to peak your motor's performance? Thanks!


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## slotking (May 27, 2008)

the best way I found is to use a dyno.

I was at a race with some top racers. 1 of them saw me with a dyno and said that he used the amp draw method and it worked the best. so we looked at the numbers on the dyno and then I tweaked it using the dyno and got more speed out of it

I do use amp draw in conjunction with top dyno reading. once i get the top speed I then do slight adjustments to lower the amp draw for most races. But if I have to race a longer race, I will up the amps a hair(turn the brushes in) so that it maintains the top speed a little longer.


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## Rich Dumas (Sep 3, 2008)

You did not say what sort of cars you were asking about. I sounds like you have a car with adjustable motor brush spring tension, I have not raced those for quite some time and my memory is a bit hazy on the correct setup. My club has not run inline magnet cars for some time, but be will be racing Spec Stock cars during the upcoming season. I have just started to convert some Wizzard Storm SS cars to that standard. I looked at some old posts that I had saved with tips on those cars, but they were for cars with bigfeet brushes, the correct settings for stock brushes is likely to be different. I seem to recall that you should turn in the retainer screws until they were flush with the ends of the brush barrels, then back the off 1 1/2 turn. I checked the original factory settings for the two cars that I converted and those had been backed off by one turn. I was told by the Wizzard himself that if you have the brush tension correct that the amp draw would be constant over a wide voltage range. If the commutator is not true a particular motor might need a little more brush tension. Here is what I would do if I was starting with new motor brushes. I would back off the brushes by 1 1/2 turns and run the motor without a rear axle in the car for 30 minutes at 3 volts, followed by another 15-30 minutes at six volts. I would the let the motor cool a little before I gave it a shot of spray contact cleaner while running at 6 volts. I would then readjust the brush tension with the screws backed off one turn. I would start at 3 volts and check the amp draw. I would ramp up the voltage and keep checking the amps to see if they held steady. For a car with a 6 ohm armature you should see about 0.2 amps. Put a little Vibratite or paint on the screws once you get the adjustment right.


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## HOcar (May 12, 2017)

Rich Dumas said:


> You did not say what sort of cars you were asking about. I sounds like you have a car with adjustable motor brush spring tension, I have not raced those for quite some time and my memory is a bit hazy on the correct setup. My club has not run inline magnet cars for some time, but be will be racing Spec Stock cars during the upcoming season. I have just started to convert some Wizzard Storm SS cars to that standard. I looked at some old posts that I had saved with tips on those cars, but they were for cars with bigfeet brushes, the correct settings for stock brushes is likely to be different. I seem to recall that you should turn in the retainer screws until they were flush with the ends of the brush barrels, then back the off 1 1/2 turn. I checked the original factory settings for the two cars that I converted and those had been backed off by one turn. I was told by the Wizzard himself that if you have the brush tension correct that the amp draw would be constant over a wide voltage range. If the commutator is not true a particular motor might need a little more brush tension. Here is what I would do if I was starting with new motor brushes. I would back off the brushes by 1 1/2 turns and run the motor without a rear axle in the car for 30 minutes at 3 volts, followed by another 15-30 minutes at six volts. I would the let the motor cool a little before I gave it a shot of spray contact cleaner while running at 6 volts. I would then readjust the brush tension with the screws backed off one turn. I would start at 3 volts and check the amp draw. I would ramp up the voltage and keep checking the amps to see if they held steady. For a car with a 6 ohm armature you should see about 0.2 amps. Put a little Vibratite or paint on the screws once you get the adjustment right.


Good suggestions. Thanks! I am working with a Wizzard Storm Extreme. I didn't think about removing the axle, which makes sense. I tested it yesterday with the axle installed at 22 VDC and it was 125 mA. I'll try different voltages and adjust accordingly.


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## Rich Dumas (Sep 3, 2008)

You might be OK. If the brush pressure was too high you would pull more amps, the motor would not rev as high as it should and would heat up too much. It is nice to have a non-contact digital thermometer with a laser pointer. Lacking a thermometer if you run the car for a few laps and it starts to slow down the motor is overheating for some reason. You might have a bind of some sort or your brush tension might be too high. If the brush tension is too low you will get arcing and that will damage the edges of the slots in the commutator. You tend to get arcing when the brushes are breaking in, which is why I start at 3 volts. If the commutator is not true the brushes will bounce and cause excessive arcing. I use hotstock armatures when that is legal and I also have a comm truing machine, but if you are stuck with a comm that is not true you will need more brush pressure.


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## slotking (May 27, 2008)

Again, the dyno is the best way to it. I have a lot of folks that so brush turn trick or just amp draw get more speed out of their cars.

I would also test amp with the axle out and then in.

you may find your gear/axle setup may cause un-needed amp draw

PM and I can send you a link to a video if you want


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## slotking (May 27, 2008)

I really thouht I had a video of T1 brush adjustment, but I can not find 1.

I would go make 1, but my dyno and other tools are somewhere in the storage place till I find a house!:frown2:


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## HOcar (May 12, 2017)

slotking said:


> I really thouht I had a video of T1 brush adjustment, but I can not find 1.
> 
> I would go make 1, but my dyno and other tools are somewhere in the storage place till I find a house!:frown2:


No problem. Thanks anyways.


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