# Excessive Brush Noise?



## PeterH (Mar 20, 2009)

I've noticed lately that my brushes are making a lot of noise. I have only 8200 miles on these brushes and I've just pulled the motor out and cleaned out the brush holders. Would you consider this normal?

While it was apart, I ran the motor for a few hours on 12VDC. If I manually turned the motor the wrong direction it really made a clicking noise. It didn't do that when new... so what's up? Should I be concerned?

Thanks,
Pete


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## dragonsgate (May 19, 2012)

Clicking? Check the com for high spots by holding your fingers lightly against the bars and slowly rotating the motor. Look inside the opening at the com end and see if the brushes are moving up and down or sideways. Have you lugged the motor or held it a stall for any period of time?


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## dougingraham (Jul 26, 2011)

PeterH said:


> If I manually turned the motor the wrong direction it really made a clicking noise. It didn't do that when new... so what's up? Should I be concerned?


When being turned backwards it is pretty normal to make a clicking sound. What happens is the the brushes are seated and the normal force causes the brushes to tip at a slight angle in the brush holders. When you spin it the other direction the brushes tip the other way and the edge of the brush catches the edges of the com segments.

I can't tell you why they would be making more than normal noise when operated in the correct direction. I have heard that some brushes have a wear indicator but I don't know how that works or if it would cause a different noise. A possibility would be contamination of the brushes. Maybe you got some dirt in the motor somehow and it is embedded in the comm or brushes. They do sound different when they are seating in. And pulling the brush out of the holders to look at it will require the brush to reseat. One thing that has been warned against is the use of Silicone lubricants used near carbon brushes. Apparently there is a way to produce silicon carbide with high voltage arcs and a carbon brush that is contaminated with silicone. When this happens it causes a rapid failure of the brushes and erosion of the commutation face.

Hope you figure it out. I will be interested in knowing what it is.


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## dragonsgate (May 19, 2012)

dougingraham said:


> When being turned backwards it is pretty normal to make a clicking sound. What happens is the the brushes are seated and the normal force causes the brushes to tip at a slight angle in the brush holders. When you spin it the other direction the brushes tip the other way and the edge of the brush catches the edges of the com segments.


It the commutator is smooth there should be no clicking in either direction. That is why I suggest checking to see if any of the bars have lifted. What motor are you running? Can you post some pictures?


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## toddshotrods (Feb 10, 2009)

I have/had the same problem on the motor I just purchased for Scrape. When I turned it clockwise (facing the DE) it was pretty quiet, but I got clicking when I would spin it counterclockwise. At JRP3's suggestions, I put it on the lathe and tried it without power in both directions, repeated the same test with all the brushes removed, and put them back in one at a time, testing each time.

The noise was definitely in the brushes, definitely much louder when spinning counterclockwise, and one brush was noticeably louder than the other three. My comm has some light marks and little chips in a couple edges, but nothing sticking up.

I put it in the bike and wired it up. I am waiting on better batteries to get here, to not completely destroy my little scooter batteries, but in the few rides I've taken around the shop (24K sq-ft, so long aisles), it seems to be getting quieter. My assumption is the same - the brushes need to re-seat themselves for the reverse direction, after having turned the other way their entire _life_. At least that's what I _think_ is the case with my motor. The commutators are relatively smooth but there is still the gap between bars, meaning a leading edge the brush encounters...


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## Old.DSMer (May 18, 2012)

I have a new K11-250 that I'm currently running on low voltage to seat the brushes. Quiet CW, clicking CCW. So I don't spin it CCW. OK for me since I'm keeping the tranny.

I did notice one set of brushes with tiny chips out of the leading edge - presumably from spinning CCW and having that edge pick up on the com bars. I have not noticed any other abnormal noises though.


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## PeterH (Mar 20, 2009)

The motor that caused this thread in the first place is a 10" Kostov with about 8K miles on it.

I only heard the clicking when turning the motor against its normal rotation.

I did run the motor for a few hours on 12VDC to help seat the brushes, and during that time I was watching the brushes and checking the commutator. Didn't notice any abnormalities at all. 

When running in the normal direction I hear a much louder brushing sound from the brushes (don't know how else to explain it) that I heard when they were new. I would think that as they became more seated, they would be quieter but that isn't the case.

While I had things apart, I compared the active set of brushes with a set that I just received as replacements. Looked like I've only used up about 1/8" of brush material which suggests I have lots more to use on that first set of brushes so they are still in the motor. 

I did clean the brush holders and the sides of the brushes of any brush dust. Didn't use any sort of lubricant, especially silicon! 

I didn't take it to work today because I didn't want to take the chance of breaking down in our current down pour... hasn't stopped raining for 3 days now...

Thanks,
Pete


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## dragonsgate (May 19, 2012)

PeterH said:


> The motor that caused this thread in the first place is a 10" Kostov with about 8K miles on it.
> 
> I only heard the clicking when turning the motor against its normal rotation.
> 
> ...


You might check to see if a bearing might be going dry.


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## PeterH (Mar 20, 2009)

Oh.... I hadn't thought of that possible problem...

However, consider this: While I had the end of the motor off (the end opposite the brush holders) and the brushes all out and with the motor up on end, I spun the commutator by hand. It spun freely and very quietly and for a long time.

Would you think the bearings, at least on the "brush-end" of the motor are ok? Clearly the sound is coming from the brush-end of the motor.

Thanks,
Pete


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## dragonsgate (May 19, 2012)

PeterH said:


> Oh.... I hadn't thought of that possible problem...
> 
> However, consider this: While I had the end of the motor off (the end opposite the brush holders) and the brushes all out and with the motor up on end, I spun the commutator by hand. It spun freely and very quietly and for a long time.
> 
> ...


Sitting on end changes the geometry of the bearing putting end thrust from the weight of the armature. You can get a better idea by spinning the bearing in your hand while it is out of the motor or set the motor up with the end plates and bearings in place but no brushes. The bearing idea is a long shot but you never know.


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## PeterH (Mar 20, 2009)

I understand your point. But at this point, I'll wait to see what happens. 
Took me all day Saturday and more than a few good cracks to the top of my head to get that motor back in place.  I'd at least like to let my scalp heal up before going back under there with my tools.

Thanks, for your input. I wouldn't have thought of that possibility... and I don't even want to guess how much trouble it would be to obtain new bearings for the motor.

Pete


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## dragonsgate (May 19, 2012)

Sometimes just taking things apart cleaning them and putting it back together makes them work better. Best of luck and I hope it runs smooth for you.


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## Old.DSMer (May 18, 2012)

The bearings shouldn't be too hard to get. When you remove the old ones, they should be identified with manufacturer and part number. That info can be cross-referenced to other brands. I prefer SKF but IKO, INA and NSK will all have crossovers.

I ruined one of the seals when I removed my motor bearing to modifying the end cap (to clear the transfer case). I picked up a new one from a local supply house for under $30.


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## Plamenator (Mar 6, 2009)

When the motor turns in one direction predominantly (as is the case with almost all conversions), brushes fine tune for that direction. When you turn it in the oposite direction, it makes a clicking noise. The clicks are relatively quiet and 50-70 clicks per complete revolution (if they are 1-2-3 per revolution, then you probably have a lifted lamella).
It is completely normal.
If you run the motor in the clicking direction for 30-120min, the clicks will disappear...only to reappear in the other direction 

In contrast, faulty bearings make a uniform whining noise.


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## toddshotrods (Feb 10, 2009)

Plamenator said:


> When the motor turns in one direction predominantly (as is the case with almost all conversions), brushes fine tune for that direction. When you turn it in the oposite direction, it makes a clicking noise. The clicks are relatively quiet and 50-70 clicks per complete revolution (if they are 1-2-3 per revolution, then you probably have a lifted lamella).
> It is completely normal.
> If you run the motor in the clicking direction for 30-120min, the clicks will disappear...only to reappear in the other direction
> 
> In contrast, faulty bearings make a uniform whining noise.


My little motor is doing exactly that, and I have nowhere near 30 minutes on it yet. It is pretty quiet pushing the bike around (power off) now, and under power all I remember hearing the last couple (really short) rides was the chain.


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