Starter Motor Brushes


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Old 09-15-15, 04:41 PM
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Starter Motor Brushes

I'm rebuilding a Lawnmower Starter Motor and one of the braided copper leads to a carbon brush has become detached from the hole in the carbon brush.

What is the appropriate means of attaching the copper braid to the carbon brush ?

Is there a way solder it ?

Is it just pressed in ?
 
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Old 09-15-15, 04:52 PM
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My guess is that it's a factory connection. I don't know if it can be reproduced manually. However, you should be able to find a replacement brush online or from an electrical supply.
 
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Old 09-15-15, 04:55 PM
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Those wires are usually molded into the brush during production. There is no way to attach anything to carbon.
 
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Old 09-15-15, 05:50 PM
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Those things aren't expensive. A lot of times you can find them in hardware stores. They are molded into the carbon with no way to repair a wire that has gotten pulled out
 
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Old 09-15-15, 07:49 PM
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An auto electric shop in your town should have some on hand. So should a small engine shop.
 
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Old 09-27-15, 02:59 PM
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I've bought several replacement Starters for my riding lawnmowers . . . . but I haven't thrown the old ones away.

What I decided to do is open a couple of them up and try to ascertain what caused them to originally weaken and fail . . . . so there's nothing urgent about what I'm doing; and I do know that I can buy replacement brushes or a whole kit including brushes, springs and new bushings. Turns out that most problems are brush related with the copper braids becoming detached from the carbon brush.

I succeeded in soldering a couple of these copper braids into the carbon brush; but because the two materials expand and contract to different extents (coefficient of expansion?), what looks like a solid connection at higher temperatures ceases as they cool and the solder/copper becomes more narrow than the hole in the carbon.

My local Radio Shack Owner suggested that I consider using an electrolytic epoxy (which he doesn't sell), to make a permanent connection. The conductive epoxies are impregnated with copper. silver, and carbon dust particles . . . . we could even make the material at home. The important thing is to make sure the epoxy is electrically conductive . . . . not thermally conductive (which would insulate the copper braid from the carbon) so that's what I'm going to do, after thoroughly cleaning everything with muriatic acid to make a decent and long lasting connection.

I'll report back if this technique works and allows me to put a couple B&S Starter Motors back in my little inventory of extra parts . . . . actually, I'll take one of the new ones off and start using one of my re-conditioned starters just to make sure it works for the long haul.

Sounds like a waste of time; but I'm curious to see if this a reasonable solution. Here in Vermont, we have to pay to throw things away !
 
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Old 09-27-15, 03:02 PM
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Waste of time.... yes. But it's your time to waste so only you can decide if it's wasted time.
 
 

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