# warp9 brush question



## major (Apr 4, 2008)

dladd said:


> from my build thread, posting here for more 'motor' eyes. in short, this motor has at least 10k on it and is only out because the car suffered from failed motor/trans mounts that did some damage. On to my question...
> 
> 
> quick question here! I just pulled the cover off the motor and peeked into the brushes. One of the brushes was not being held in by it's clip, as shown in the first photo below. I played with it a bit before taking this picture, so I don't know if all those marks were already there, or if I made them by putting the clip on and off before taking the photo.
> ...


Hi dl,

Nice catch.  Shows that maybe all should do a 10k inspection. What you call clips are the springs, one per brush. There are actually 4 brushes per polarity, so with one "clipped" up out-of-contact with the comm, the other 3 brushes are forced to carry higher current density, so would wear a bit faster than normal. And the clipped up brush was not wearing at all.

Actually I don't think it did any damage and will do O.K.once you put the spring back in its proper place. The difference in brush length compared to its neighbor isn't too bad.

I doubt that the spring moved out of place on its own during operation. It likely was not positioned properly when installed. Every once in awhile, I see a motor with a missing spring, or a broken spring, but can't say as I've seen this before. 

Nice photos 

Regards,

major


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## dtbaker (Jan 5, 2008)

a related question is.... how far down can the brushes be worn before you need to replace'em? I live on a dirt road, and expect that the extra dust will wear mine a little faster than most....


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## Salty9 (Jul 13, 2009)

Brush examination would be a good excuse to buy a fiberoptic camera TV. I've been trying to convince myself I need one since I saw one at Costco for $150.


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## major (Apr 4, 2008)

dtbaker said:


> a related question is.... how far down can the brushes be worn before you need to replace'em? I live on a dirt road, and expect that the extra dust will wear mine a little faster than most....


Hi dt,

That is a good question. The motor company should tell you this. My old company, waybackwhen, would supply this info to OEMs and publish it service manuals. I have not seen such for EV motors. Maybe Netgain can tell you. Let us know what they say 

Barring that, I'd say about half way. Those wires going into the top of the brush are called shunts, sometimes pigtails. They go down inside about half an inch (maybe more or less). You certainly don't want the brush to wear down where these shunts are exposed and contacting the comm. The other thing to watch, with these types of springs, is that as the brush gets shorter, the force reduces. This can cause accelerated electrical wear of the brush. So it is best to service and replace brushes before they get too short as the last bit goes faster than the first.

Regards,

major


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## dladd (Jun 1, 2011)

major said:


> Actually I don't think it did any damage and will do O.K.once you put the spring back in its proper place. The difference in brush length compared to its neighbor isn't too bad.


cool, thanks. One less thing to worry about.  



> Nice photos
> 
> Regards,
> 
> major


taken with my DroidX! It's such a good camera I don't even own a camera anymore...

david.


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## marc02228 (Jan 15, 2011)

What means 10k?
10.000 Miles?!?


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## dladd (Jun 1, 2011)

marc02228 said:


> What means 10k?
> 10.000 Miles?!?


10,000 miles.


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## major (Apr 4, 2008)

dladd said:


>


I just noticed this  It appears that the markings on those two brushes are different. That is unusual. I would send this photo and your story to the place from which you bought the motor or to Netgain. It is possible that the one troubled brush was replaced with an incorrect one and not installed correctly.


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## dladd (Jun 1, 2011)

major said:


> I just noticed this  It appears that the markings on those two brushes are different. That is unusual. I would send this photo and your story to the place from which you bought the motor or to Netgain. It is possible that the one troubled brush was replaced with an incorrect one and not installed correctly.


All the brushes have the same markings, they is a symbol on them, and under that it says ML1693.


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