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wjohn 
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Joined: 19 Jan 2010
Location: KS
Points: 2283
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 Topic: Starter/Generator Soldering
Posted: 21 Dec 2025 at 3:50pm |
I was putting new solenoid contacts and brushes in the starter in my truck, and discovered halfway through that the brush leads are soldered to the windings (seems some are and some aren't on the Denso starts used in Cummins engines). I ordered a new starter for now and moved on... But I've always wanted to learn to do more on starters and generators seeing as we can't just go pick up a new on from our local auto parts store for our old tractors.
What is the tool of choice for something like this? I can tell it is going to take a lot of heat since the copper is pretty thick and is going to wick a lot of heat away... Big soldering iron? Torch?
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1939 B, 1940 B, 1941 WC, 1951 WD, 1952 CA, 1956 WD-45
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steve(ill)
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Joined: 11 Sep 2009
Location: illinois
Points: 89244
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Posted: 21 Dec 2025 at 4:50pm |
BIG old time solder iron.. Not a newer solder gun...
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Like them all, but love the "B"s.
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jaybmiller
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Joined: 12 Sep 2009
Location: Greensville,Ont
Points: 24893
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Posted: 21 Dec 2025 at 5:11pm |
I'd think they'd be 'silver soldered' NOT 'plumber's solder. Just had the starter die on my '97 F150. The braided copper wire from the solenoid into the brushes corroded away. $150 replaced it but what a 'silly' idea having bare braided copper wire exposed to water,especially salty water.
Sad thing is IF I could find the part,it's a simple 10 minute repair.
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3 D-14s,A-C forklift, B-112
Kubota BX23S lil' TOOT( The Other Orange Tractor)
Never burn your bridges, unless you can walk on water
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Clay
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Joined: 11 Sep 2009
Location: Udall, Kansas
Points: 10155
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Posted: 21 Dec 2025 at 6:33pm |
I just rebuilt the starter for my 1983 F-250 6.9 idi diesel. The brushes were worn out. Armature, bearings and windings were in good condition. I used silver solder on the fields and braided copper wire. Only cost me $15 for the parts as opposed to around $200 for a replacement starter.
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jaybmiller
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Joined: 12 Sep 2009
Location: Greensville,Ont
Points: 24893
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Posted: Yesterday at 7:53am |
Hat Clay...googled 'brushes' for my 4.6.... NAPA want, $75+ Complete starter was only $150 for me, from NAPA....11 minutes down the road.
found some on Amazon.CA for $10 !!! Since I haven't tossed out the old starter, I'll order them and turn in into a 'winter project'. Need to get granddaughter to order them !
THANKS !!!
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3 D-14s,A-C forklift, B-112
Kubota BX23S lil' TOOT( The Other Orange Tractor)
Never burn your bridges, unless you can walk on water
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SteveM C/IL
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Joined: 12 Sep 2009
Location: Shelbyville IL
Points: 8742
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Posted: Yesterday at 10:15am |
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I'd like to know trick to silver soldering. Had no luck trying to solder a banjo fitting on injection line. I'm guessing clean is the key as with regular soldering but no joy. Used small oxyacetelene fire.
Edited by SteveM C/IL - Yesterday at 10:17am
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wjohn
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Joined: 19 Jan 2010
Location: KS
Points: 2283
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Posted: 17 hours 59 minutes ago at 10:21pm |
 Clay wrote:
I just rebuilt the starter for my 1983 F-250 6.9 idi diesel.The brushes were worn out. Armature, bearings and windings were in good condition. I used silver solder on the fields and braided copper wire. Only cost me $15 for the parts as opposed to around $200 for a replacement starter. |
You used a torch of some sort then?
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1939 B, 1940 B, 1941 WC, 1951 WD, 1952 CA, 1956 WD-45
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Les Kerf
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Joined: 08 May 2020
Location: Idaho
Points: 1490
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Posted: 8 hours 20 minutes ago at 8:00am |
SteveM C/IL wrote:
I'd like to know trick to silver soldering. Had no luck trying to solder a banjo fitting on injection line. I'm guessing clean is the key as with regular soldering but no joy. Used small oxyacetelene fire. |
I have silver soldered a million+ (seriously) carbide saw tips on sawmill saws during my 30 years as a saw filer in the big mills here in Idaho. Yes, the key is cleanliness and proper flux.
I doubt that silver solder will stick to parts that have been long-term contaminated with diesel 
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Tbone95
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Joined: 31 Aug 2012
Location: Michigan
Points: 12328
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Posted: 8 hours 10 minutes ago at 8:10am |
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I don’t recall doing anything electrical with silver solder but I have done large copper tubing and sheet work. Clean, flux, I didn’t find it anymore difficult than regular solder, just maybe a little slower flowing due to the higher temperature. Been a good many years though.
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Les Kerf
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Joined: 08 May 2020
Location: Idaho
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Posted: 1 hour 43 minutes ago at 2:37pm |
steve(ill) wrote:
BIG old time solder iron.. Not a newer solder gun...
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My Bro-in-law has a big ol' honkin' soldering 'iron' that is actually made of copper, it weighs about two pounds or so, you just heat it up with a propane torch and let 'er rip; I borrow it whenever I (rarely) need to do some heavy duty soldering.
The last time I used it was when I modified the starter on my Allis Model C to eliminate the manual push button, I soldered a copper bolt onto the contact stud to facilitate connecting the starter to the solenoid (relay). I just used regular nasty old lead-based solder. So far so good.
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Clay
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Joined: 11 Sep 2009
Location: Udall, Kansas
Points: 10155
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Posted: 15 minutes ago at 4:05pm |
Clean the surface. Clean the surface. Clean the surface. Roughen the area to be soldered. Place a heat deflector between the fields and the heat. Flux and tin the surface. Flux and tin the brush lead. Be absolutely certain to use a pair of needle nose vise grip pliers as a heat sink. You do not want the solder to wick up the conductor as it would make it stiff. I used a very small acetylene torch to warm the area to be soldered. Mapp gas will work also.
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