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Old 01-13-2017, 05:01 AM   #1
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Talking Brushed motors in2017. Break in, comm drops, graphite brushes, zappers +neodymium etc

Hi guys.

It's a shame that brushed motor tuning is now a dead black art due to the popularity of maintenance free brushless tech. (boring...)

So as it stands, I have a few brushed race motors and brushed ESCs that I would like to keep in service for as long as possible. These are fairly rare and only have a finite lifespan.

1. comm drops. I've read through Big Jim`s motor guide however he is recommending products that are no longer available. So I'll need to find some kind of alternative. Some people have said they are a waste of time. I'm really not interested in some kind of unscientific snake oil sales pitch... but with the amount of wear I see on my comms, some kind of solution is needed. And drilled and cotton packed brushes soaked in comm drops (engine oil conditioner: whatever that is?)

2. break in method? single brush at a time + slave motor in kerosene? I'm not entirely sure why some people are so strongly for or against the water method?

3. self lubricating brushes? graphite? as far as I'm concerned, brushes are consumable throw aways. Armatures: not so much. This seems good however my lowest turn motors are 6x1, 9x1, 12x1, 14x2, 15x2, 19x2, 23x? and a hand full of silver can + mabuchi armatures as well. I'm concerned that graphite brushes will carry too much resistance significantly increasing heat, arcing and excessively killing power. Thoughts? I can see silver brushes will have more friction and is a harder material thus aggressive comm wear?

4. Some of my magnets seem to have been over heated throughout the years and seem quite weak. I haven't been able to find a zapper for sale. failing that, I assume by now there should be stronger rare earth / neodymium magnets available for brushed 540 cans?

5. Ceramic ball bearings make me a jerk???

6. brush spring pressure. Too much = bad comm wear. Too little = bad comm wear...

Lastly, just so no one asks, I already have a comm lathe, brush serrator, brush hood alignment tool, a ballistic novak 4.5T and 3.5T brushless systems so don't open that can of worms.

So any info will be much appreciated. Hopefully I can keep these old motors turning for many more years to come.
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Old 01-13-2017, 06:45 AM   #2
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This may seem like an obvious question, but how do you intend on using these brushed motors? Are you going to be racing, bashing, putting them in shelf queens that see limited use, or something else?

I was never any good at tuning brushed motors, so I don't miss those days. However, I would stay away from any type of "racing" comm drops if you are tying to get maximum life out of a motor. Those type of comm drops were more for a short term gain in power/performance. Most people using them would skim their comms after 1 or 2 runs and probably replace the brushes just as often.

I was primarily racing oval when brushed motors were king. At the top level, everything in a brushed motor was considered a consumable and as such was disposable. Racing motors with lay down brushes would wear down the comms, especially if you were using hard springs. Towards the end of the competitive brushed era, there were motors with angled brush hoods that weren't as hard on the comms.

If you are reading a motor tuning guide, bad comm wear doesn't necessarily mean that it is wearing out the comm. In the case of too light of a spring, bad comm wear would mean that too little off the squarish end of the brush was in contact with the round comm. With too light of springs, it would take forever for the brush to "seat" against the comm which resulted in a loss of power. You could use a brush serrator to help shape the brush end to help speed up the seating process.

I would recommended reading about or finding someone who knows how tune brushed motors for 1/12 scale cars. Since 1/12 cars were lighter, ran on 4-cells, and ran longer heats, the motors were tuned less aggressively than a 6-cell touring car. Which leads to the question of what type of power are you planning on running through the motor. A battery with less voltage such as a single cell lipo won't be as hard on a brushed motor as compared to a 2 or more cell lipo.

Again, I'm not a brushed motor guru. However, my best advice is to buy/find spare parts such as commutators. I would also recommend using a motor can that came from the factory with bearings instead of brass bushings. You can always replace bushings with bearings, but if you don't get the bearings (or bushings) seated properly it will shorten the life of the commutator. Either way, make sure to have bearing oil or bushing oil depending on the type of motor you are using.

You also might consider looking for an older style charger that has built-in motor break-in options. The Duratrax Ice is a decent older charger than can run a motor and it can also charge lipo batteries. I'm not sure if newer chargers still have brushed motor break-in options.
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Old 01-13-2017, 07:10 AM   #3
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I really only intend to give them a gentle life. I only plan on doing laps by myself at the local track. Just going through a couple of packs at a time before changing motors or playing with other settings / hardware. I wouldn't consider racing them or even bashing them as I use brushless systems for that. I would consider rationing these armatures like fine aged liquor.

This is more for nostalgia purposes and to tinker with old tech. I also still use NiCds just for fun. I have all of the old style high end chargers so that isn't an issue. For motor break in, I use a lab power supply. Though I have just learned of the slave motor method: using an external motor like a drill so there is no arc on the comm. I also suspect kerosene would make a good cutting lubricant like a wet stone. Naturally, I wouldn't bother with bushings. Every watt and every amp wasted is just going to turn these motors back into dust.

I also contemplated getting some of those motors with the vertically angled brushes... though my brush cutting / alignment tools aren't up to that task... Though I could kill for a fussy brush serrator kit. This stuff is actually getting pretty hard to get

I'm really looking forward to hearing more input from 1/12th guys... or whoever knows this stuff better than us.

Last edited by KoroKoro; 01-13-2017 at 07:45 AM.
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Old 01-13-2017, 09:06 AM   #4
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Quote:
Originally Posted by KoroKoro View Post
Hi guys.

It's a shame that brushed motor tuning is now a dead black art due to the popularity of maintenance free brushless tech. (boring...)
99% of racers who were around in the brushed days would disagree. Brushless is the best thing to have happened to RC racing (closely followed by Lipo batteries).

Brushless is faster, cheaper, has near-zero maintanance, and is more tunable (if you race a boosted class).
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Old 01-13-2017, 09:27 AM   #5
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If your looking for com drops.

Black drops are Liquid Wrench.
Clear drops are valve lube, used for the slides on trumpets, you should be able to get it at any music store.

Both items should still be readily available.

And I'm the 1% I guess, lol.
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Old 01-13-2017, 12:39 PM   #6
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Can anyone comment on if it was better to true the comms to a shiny/reflective finish or a dull finish?

Which reminds me that you needed to have a sharp cutting tool mounted properly on your comm lathe, which I don't regret not having to deal with any more. I also don't regret having to settle with the carbide cutting tool because I couldn't afford the diamond tool.
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Old 01-13-2017, 12:41 PM   #7
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KoroKoro, "a dead black art", that depends on how old you are. I still have a 10L equipped with a brushed motor. And by the way, dipping a running motor in water seems to be the best and easiest way to break in a motor.
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Old 01-13-2017, 12:45 PM   #8
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Originally Posted by IndyRC_Racer View Post
Can anyone comment on if it was better to true the comms to a shiny/reflective finish or a dull finish?

Which reminds me that you needed to have a sharp cutting tool mounted properly on your comm lathe, which I don't regret not having to deal with any more. I also don't regret having to settle with the carbide cutting tool because I couldn't afford the diamond tool.
I always trued to a shiny finish, and deburred the comm afterwards. They Carbide tool did a great job too, just required a bit more time and patience and you would easily be able to make quite as long.

I still have my Reedy Comm Lathe and Motor Analyzer. Also have my brush Cutter and Hood Alignment tools.

I still run brushed motors in all my older vehicles that are sitting on the shelf lookin period correct.
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Old 01-13-2017, 01:03 PM   #9
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Brushed motors can still race in very small carpet tracks if you plan to only have two runs per motor... I really like their sound compared to brushless, but racing them should be done occasionally, not every week or you will run out of armatures, brushes, etc....
These old motors might be worth something in the future, so don't throw them away....
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Old 01-13-2017, 01:30 PM   #10
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Quote:
Originally Posted by daleburr View Post
99% of racers who were around in the brushed days would disagree. Brushless is the best thing to have happened to RC racing (closely followed by Lipo batteries).

Brushless is faster, cheaper, has near-zero maintanance, and is more tunable (if you race a boosted class).
Plenty would disagree with you, it has also created the racer who does not really know how to do anything other than open their wallet and shortly gets discouraged because the veteran racers are still tuning brushless as much as brushed with equipment that includes Motolyzers, Dyno's, Gauss, and milli-ohm meters. Easy, maintenance free, last forever are good buzz words to replace learning how to do anything.
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Old 01-13-2017, 01:41 PM   #11
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long live Miller lol
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Old 01-13-2017, 06:53 PM   #12
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Originally Posted by daleburr View Post
99% of racers who were around in the brushed days would disagree. Brushless is the best thing to have happened to RC racing (closely followed by Lipo batteries).

Brushless is faster, cheaper, has near-zero maintanance, and is more tunable (if you race a boosted class).
mate... I think you've missed the point. LOL

I just had a chat at my LHS. Picked up some brushes, springs etc etc and a fancy new 10T motor They didn't have any graphite brushes though Plenty of fancy extra hard silver ones though. Which begs the question... why didn't they make the comms out of silver. Maybe I should electroplate my comms? I suppose that would help them last longer?

He suggested that comm drops would only accelerate comm wear and are marginally pointless for races longer than 3 minutes. He suggested just running them dry.

We also spoke about break ins as well. He only broke them in dry on his car. He said that the water method was only for motors without ball bearings and was only to break in the bushes. Any truth to this?

I'm still no closer to finding a magneto charger either (magnet zapper)
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Old 01-13-2017, 07:08 PM   #13
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Originally Posted by KoroKoro View Post
mate... I think you've missed the point. LOL

I just had a chat at my LHS. Picked up some brushes, springs etc etc and a fancy new 10T motor They didn't have any graphite brushes though Plenty of fancy extra hard silver ones though. Which begs the question... why didn't they make the comms out of silver. Maybe I should electroplate my comms? I suppose that would help them last longer?

He suggested that comm drops would only accelerate comm wear and are marginally pointless for races longer than 3 minutes. He suggested just running them dry.

We also spoke about break ins as well. He only broke them in dry on his car. He said that the water method was only for motors without ball bearings and was only to break in the bushes. Any truth to this?

I'm still no closer to finding a magneto charger either (magnet zapper)
Silver is a lot more expensive than copper. Almost an order of magnitude more expensive. There's relatively not much silver additive in the brushes, but a comm is a solid hunk of copper. Making a silver comm would significantly increase the cost.
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Old 01-13-2017, 08:29 PM   #14
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A diamond tipped bit on a Team Cobra lathe would be worth every penny in your case. True the comm until it's a smooth consistent surface/finish on the face. Take an xacto blade and clean the slots while gently removing any burrs on the leading and trailing edge. Use a higher content silver brush with a serrated face. Give each edge of the brush a very, very light filing. Use a red spring on the positive side and green on the negative.

This will work very, very well for most any application. I have worked on many a brushed motor...more than I care to remember. The key was always starting with a very good base motor and then tuning it from there. Thanks to Team EAM (Eric Anderson), I always had great motors and brushes.
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Old 01-13-2017, 08:41 PM   #15
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Oh and BTW, if you're that determined to learn what's working, spend your money on a Fantom Facts Machine Dyno and forget the magnet zapper. While zappers can help, the dyno is a must to understand the impacts of the changes your making. The dyno is invaluable.

I also think you're worrying about the break-in process way too much. Follow the above, spin it up on the dyno, then go out and run it.
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