Silver Solder question

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WallysmotordemonsWMD

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Jun 2, 2014
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I've seen lots of posts about fabricating your own cable ends and for re-jetting carbs. All say to use silver solder, regular plumbing or radio shack stuff won't work. But there's a bunch of varieties of silver solder 3% 5% 9% 45% 56%, The higher percentage stuff is sometimes called silver brazing alloy. So what percentage do i go with? What would be the most useful thickness? Links and/or pics would be helpful
Thanks!
 
2door

2door

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Sep 15, 2008
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Don't confuse 'silver solder' with 'soft solder'. Silver solder typically is a high temperature brazing alloy that requires much more heat than you'll ever want or need to solder carburetor jets or ignition wiring. Many people incorrectly call soft solder, silver solder becuae it is silver in color. They aren't the same animal.

I've successfully used 60/40 lead based solder as well as 50/50 for jets using an electric soldering gun. Same for ignition wiring splices. You'll get two schools of thought on flux core verses solid core solder. I'm one who uses solid core and paste flux. Some prefer the flux in the solder. Whatever spins your crank and works for you.

Tom
 
maniac57

maniac57

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Oct 8, 2011
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Agreed. The higher the silver content, the harder the solder and the higher the heat needed for proper bonding.
I personally prefer flux, but the rosin core is fine for electrical work and much easier to use.
The better you clean the joint, the better it will work regardless of which you use.
At the higher percentages, you're likely to damage the cable itself since the required heat is so high. I like 60/40 for most heavy duty soldering.
 
bairdco

bairdco

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Aug 18, 2009
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i use a mig welder to make throttle cable ball ends now. one zap and you've got the perfect size to fit into the carb slide.

i've used different types of solder before for throttle cable balls, but had one come off and disappear into the engine somewheres.

for electrical connections i use the cheap, thin solder that comes spiraled up in a little tube.

for barrel ends on cables i use silver solder, paste flux, and a propane torch. there's a post here somewhere about "how to make your own cable end mold"
 
CTripps

CTripps

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Aug 22, 2011
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bairdco said:
i use a mig welder to make throttle cable ball ends now.
...for barrel ends on cables i use silver solder, paste flux, and a propane torch.
Click to expand...
I've been experimenting with making new throttle cable stops or ends, so I can start shortening the cables to fit. So far the best luck I've had is by using a torch and wrapping a thin strand of copper wire around the cable tip then dipping it in a tiny crucible (old socket driver held upright in a vice) of solder to coat it. A couple of dips and it's about the right size. I haven't tried one on a bike yet, still just trying different things on off-cuts from clutch cables.

I hadn't thought of that appraoch, though.. I'll try it with the welder, now that you've mentioned it.
 
silverbear

silverbear

The Boy Who Never Grew Up
Jul 9, 2009
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CTripps said:
I've been experimenting with making new throttle cable stops or ends, so I can start shortening the cables to fit. So far the best luck I've had is by using a torch and wrapping a thin strand of copper wire around the cable tip then dipping it in a tiny crucible (old socket driver held upright in a vice) of solder to coat it. A couple of dips and it's about the right size. I haven't tried one on a bike yet, still just trying different things on off-cuts from clutch cables.

I hadn't thought of that appraoch, though.. I'll try it with the welder, now that you've mentioned it.
Click to expand...
What I do for cable ends is a variation of your copper wire method and it works fine for me.I figure out where I want the cable to end, but at this time I don't cut it off. Instead I use an awl (ice pick or anything pointy) to make a "hole" between the strands of cable, big enough that I can work a few strands of thin copper wire into the hole and then wrap it around the cable a couple of times. A bit of paste flux , solder (whatever kind you have, but the type of flux must match), give it heat to melt the solder and in no time the copper acts almost like a magnet attracting the solder to itself... much moreso that the steel cable. Now you have a nice cable end blob that may need to be shaped a bit with a file, sandpaper or easiest of all your dremel type rotary tool. Now snip off the excess cable at the end of your solder bead. I've never had one come apart. Describing how to do it takes longer than doing it. Ha!
SB
 
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CTripps

CTripps

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Aug 22, 2011
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That sounds good too, thanks Silverbear. Next time I'm playing with it I'll try that too. I had tried copper wrapped around the cable and thn heating it and trying to let the copper wick in solder, but it just wasn't working for me.. Getting the heat just right is the trick, otherwise the bead usually dripped right off or blobbed on to the side and would 'snap' off.
 
2door

2door

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Something to keep in mind is that soft solder, like 60/40, 50/50, solid core used with flux or rosen core solder won't stick to stainless steel cable. If your cables are stainless you'll have to use high temp brazing alloy or Bairdco's weld bead method. That, or crimping.

Brass tubing, like the K&S brand sold in hobby shops and some hardware stores works well for cable ends if you're making a throttle cable. I use 1/16" ID tubing, cut to about 1/8" long soldered to the cable to act as a stop to lift the throttle slide. It is a little less labor intensive than wrapping with small copper wire and makes a nice clean cable end. I also use it on the end of the clutch cable to keep it from fraying.


As has been posted here before on this subject by me and others, cleanliness is the key to soldering. The cable must be free of dirt, oil, grease, rust, oxidation or any impurity. Solder won't stick to any of those and will bead up and roll off. Heat control is also critical. Too cold or too hot and the solder won't stick or flow.


Tom
 
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