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Old 07-08-2004, 08:03 PM   #1
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Default Sparks visible in motor - What the ???

I just changed ESCs in my car, and I dropped all of the Dean's connectors to go straight wired. I was so anxious to see it run (it has been down for almost 2 weeks), I put a quick charge in a battery and went outside.

Since it was dark, and I was running without the body, I noticed something - closer inspection revealed visible sparks inside the endbell of the motor. I have always had an overheating problem with motors (not just this one) but I am sure this is a sign of something not quite right.

What is this telling me? Is this just an indication that the brushes need to be replaced, or that the comm needs to be cut, or both, or ???

This motor has two 5 minute runs on it since a comm cut and brush replacement.
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Old 07-08-2004, 08:29 PM   #2
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rctoyguy- those sparks in the motor are fine. Tells you there is friction between the comm and brushes, and i dont think you need to cut the comm after only 2 heats. I think there is nothing wrong, if your having heating problems check your gearing and mesh.

Hope it helps

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Old 07-08-2004, 08:31 PM   #3
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Motors spark for a few reasons, but most of the time, I'd say they spark because of poor contact between the brushes and the comm. This could be because your brushes haven't seated properly, the brush hoods are out of alignment, the comm is out of round, or you're getting brush bounce. If the springs aren't maintaining adequate pressure on the brushes, it's going to make intermittent contact with the comm, causing sparking.

I'm sure there are other reasons this could be happening, but these are the ones I can think of off hand.

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Old 07-08-2004, 08:33 PM   #4
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I have geared and regeared till I don't know what to do, and the best I can tell I have the car freed up enough. The bearings are good, the belt seems good (black belt on XXX-S) and the gear mesh looks right...

Oh well, the overheating is another issue that I am fighting. I was mostly concerned about the sparks, that just didn't seem right to me.
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Old 07-08-2004, 08:39 PM   #5
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You will get sparks.. Nothing wrong here,Now on the gearing,what is your final ratio..
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Old 07-08-2004, 08:42 PM   #6
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When you break in your motor, you will see a lot of sparks in the beginning but after the brushes are seated in, there should be LESS sparks. Totally fine.
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Old 07-08-2004, 08:50 PM   #7
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Running 88 / 23 right now. On my chart, that comes out to 7.00 and a rollout of 1.12 - XXX-S, stock, rubber tire, outdoor asphalt with Niftech traction compound.

It is very hot here (Birmingham, AL) and I have had motor temps in the 220 - 250 range. I have not checked other folks motors to see actual temps, but everyone says they are running hot.
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Old 07-08-2004, 08:54 PM   #8
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There will always be sparks at the brushes as they wrap around enough (especially on laydowns) to short out comm segments at the tips.

Each comm segment is ~120 degs, laydowns cover about 150 degs each.
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Old 07-08-2004, 09:17 PM   #9
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Ok,now what motor are you running,I know that alot of people are running ratios in this range,But for the most part I'll gear in the 7.50 range for a monster or epic,at the tracks I run,gearing in the 7.00 and lower dont work very well..smaller tracks and very hot(105 in the shade..track temp in the 150's)The temp your motors are running at seem a bit on the high side.
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Old 07-08-2004, 09:23 PM   #10
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The motor that is currently in the car is a Monster Stock with a Trinity arm in it (cooked the original arm) - I have the same situation with a Hellfire and with a Putnam green can stock.

Is it possible to gear too low and have heat problems?
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Old 07-09-2004, 03:09 AM   #11
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i agree, maybe ur brushes have not yet seated properly. basically, sparks are normal.
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Old 07-09-2004, 04:10 AM   #12
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If you do this everytime you clean your brushes it will reduce sparking a lot.
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