Replacing starter motor brushes - solder, weld or crimp?

jimster · Spanner Monkey Joined: 16 Mar 2005 Karma :

Hi all,

I am going to replace the starter motor brushes on my starter motor for my Yamaha Diversion 900. I only have a soldering iron and I've realised they might be welded. Do I need to weld on the replacements? Or can I get away with soldering / crimping them in?

And if solder, what power soldering iron am I likely to need? I have 25w and 40w. Lidls have a gas powered soldering iron in this weekend @ the bargain price of £15, so that's another option.

Thanks Smile

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Current: Yamaha Diversion XJ900
Previous: Yamaha Diversion 600cc, Piaggio Zip 50cc, Honda CG125-W, Siamoto Caddy 50cc moped

jeffyjeff · World Chat Champion Joined: 02 May 2020 Karma :

I'd say the brushes are probably soldered on. Your 40W soldering iron should do the trick. See if you can find something to wedge the brushes in the brush holders when you solder the pigtails. That way, you don't fight the action of the springs and have both hands free for the solder job. Afterwards, remove the wedges to allow the brushes to spring against the commutator.
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History shows again and again how nature points out the folly of men - BOC

struan80 · World Chat Champion Joined: 04 Nov 2014 Karma :

Solder. Any of the irons will do the job. Just may take longer to heat the metal and flux.

Strangely enough I used to solder brushes on DC motors when I was in the Navy 35 years ago. I'm shit at soldering on a circuit board though. I'm too shaky due to my drinking habits.

On another note, just buy a recon starter.

WD Forte · World Chat Champion Joined: 17 Jun 2010 Karma :

They will not be welded.
They'll either be soldered or have terminals crimped on the copper braid pigtails and fastened by screws or crimped to the terminal lugs.
This is why you ought to 'Test don't Guess' and
examine it first before spending money.

How do you even know if they're worn?
I serviced a 21 year old starter last year that only needed a damn good clean out (I used carb cleaner) and the commutator polishing up.
the brushes were nowhere near the service limit.

If the brushes are below the service limit you can buy the whole kit
base plate, springs and new ready attached attached brushes for £60 ish
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bikenut · World Chat Champion Joined: 21 Nov 2011 Karma :

What do the CMSNL exploded views suggest.

They tail wires etc may be spot welded...

What year etc is your divvi ?
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jimster · Spanner Monkey Joined: 16 Mar 2005 Karma :

jeffyjeff · World Chat Champion Joined: 02 May 2020 Karma :

On automotive starters, sometimes the brush holders have two small holes drilled into them. You can depress the brush into the holder, compressing the spring, and insert a paperclip wire through the holes to retract the brushes for ease of assembly.
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History shows again and again how nature points out the folly of men - BOC

WD Forte · World Chat Champion Joined: 17 Jun 2010 Karma :

Here's a Divvy starter service kit from Ebay
It looks to me that the brush tails are crimped to the base on the earth side and have an eyelet terminal attached to a peened over stud on the positive side.
You could of course cheap out and buy individual brushes to try to fit them yourself, or just cough up the dosh.

I still maintain you should examine the fecker first
instead of playing swap and hope.
There's more to starter motors than brushes, what if the commutator
is burn out,winding insulation heat damaged or bearings and seals worn?

https://i.ebayimg.com/images/g/l7wAAOSwnz9br0u3/s-l1600.png
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bikers smell of wee

ZebraDriver · Scooby Slapper Joined: 13 Feb 2011 Karma :

Be careful if your trying to solder the leads on the brushes shown in the photographs. Its too easy to have enough heat in the wire to make solder wick along it making it rigid enough to snap later on when it tries to move.

Pete. · Super Spammer Joined: 22 Aug 2006 Karma :

bikenut · World Chat Champion Joined: 21 Nov 2011 Karma :

Google CMSNL, follow your nose and find your exact bike.

Find the exploded view of interest.

Find the number of the part of interest.

Find the part in the list, and open the picture of the actual part....
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B1N · Scooby Slapper Joined: 13 Feb 2022 Karma :

bikenut · World Chat Champion Joined: 21 Nov 2011 Karma :

Don't thank me, thank CMSNL. A really handy informative and free resource.
I even buy stuff from them occasionally.
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jimster · Spanner Monkey Joined: 16 Mar 2005 Karma :

jimster · Spanner Monkey Joined: 16 Mar 2005 Karma :

Pete. · Super Spammer Joined: 22 Aug 2006 Karma :

buddy · Trackday Trickster Joined: 07 Mar 2009 Karma :

Tldr BUT
be careful if you solder them.
Last time i used too much flux... As a result the solder flashed down onto part of the copper "copper ribbon/cable/wire/whatever u wanna call it" resulting in a brush that was stiff on its cable.... Very annoying.

The moral is be stingy with the solder and flux.
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When this baby hits 88 miles per hour... you're gonna see some serious shit.