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 ?

 

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.

 

Those wires are usually molded into the brush during production. There is no way to attach anything to carbon.

 

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

 

An auto electric shop in your town should have some on hand. So should a small engine shop.

 

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 !

 

Waste of time.... yes. But it's your time to waste so only you can decide if it's wasted time.