pappyman

I have to make some throttle cables for some VW trikes that I have built....some I bought cable making supply's but need to solder on the barrel end onto the wire its a brass barrel and steel wire
Would silver solder be best ?? and I know its harder to work with silver solder are there any tricks to get a good joint should I use a oxy/acetylene as a heat source rather then a propane torch
I know silver soldering take skill but I need to know any tricks to use because I dont have time to practice

jrs_dodge_diesel

Propane torch should be plenty enough heat.

Silver solder is unfamiliar territory for me. I am an electronics technician , and all of my soldering experience is on circuit boards and RF connectors. If silver solder is anything like elex soldering, get the item hot BEFORE you apply the solder, this prevents a cold solder joint that could fail.

Jeff in TD

Silver solder isn't too bad. Just make sure everything is clean, and get the parts hot enough to wick the solder into the connection, but with small parts like that it could be easy to get them too hot with either propane or oxy/acetylene...

Do you have a solder tip for the propane torch? It may take a minute or so to get things hot enough that way, but it may give you more control of the heat...

AlpineRAM

For the old VW engines we usually took the barrel end with a setscrew to fix it where we wanted instead of soldering it.
IMO silver solder should be good, but take extreme care that you have the end of the cable degreased really good and that no grease wicks back into the joint while heating it up for soldering.
For vehicles where we wanted the look of something done nicely we used a small conical screw that we screwed into the cable where it passed the cylinder. We fixated it with epoxy. The trick is to get enough lateral pressure of the single filaments against the wall of the hole.

HTH

AlpineRAM

John Faughn

Clean off with brake clean , then put on soldering paste , use MAP gas , comes in same bottles as propane [ small hand held ] , its hotter for the silver solder , do not use ox ac , too dirty = weak connection , no propane not hot enough for silver solder .

BC847

There are fluxes that are appropriate for silver solder work. Be sure to use it as the joint you propose is not self-fluxing (self-cleaning).

There are silver solders that have differing percentages in silver content. The silver content effects the solder's "wetability" meaning, the higher the silver content, the more the liquidus solder will run into tight spaces.
You'll most likely do well with a silver solder of 15% silver content. Using such in your application will result in an overall better joint (strength wise). A lower silver content, say 5%, will require more heat to get the solder to wick into the cable. Such will most likely anneal the cable to a point that it's durability in your application will suffer dramatically.

You'd do well to get an old cable and practice a time or two as the bottom line is you don't want the cable to go "Red Hot" thereby annealing (softening) the metal. The normal temperature involved in silver soldering can range from 1100*F to over 1600*F pending the percent silver in the mentioned ranges.

Mapp gas should work though oxy/act can, pending the burning mix percentages can effect how the metals bond (oxidizing/carburizing).

Hope this helps more than confuses.

pappyman

All your replies help
I have been welding on bikes for 40 years but this is new to me so I'll try y'all advice and hope for the best
Guess my Lady's trike will be the test trike if the joint breaks I know she's only a cell phone call away

bentwings

If I'm not mistaken these cables are stainless steel. At least the good ones are. You need to get the right flux for this. As noted try it out first even if you have to sacrifice a cable.

Real silver solder is like a low temp braze. It melts or flows in the 1100- 1200 deg range rather than 1600 of brazing. Top of the line solder is about 490 deg F. The weld shop can help you select the right alloy and flux. Golden rule ....keep it clean and be sure that grease from up the cable doesn't wick in. Don't get it too hot.

mj007

Braze it

TreeFarm

Sta-Brite #8 low temp silver solder. It flows at temperatures similar to lead solder and is very strong. You don't need a torch. You can use a decent sized soldering gun. Use their flux, but be sure to rinse if off well; it's acidic.

BTW, some regular silver solder contains cadmium, which is quite toxic. You are more likely to find it in old stock, but you should always check to be sure.