Preferred Solder for Automotive Wiring

[DoubleDingo]

I normally use butt connectors on wiring, however, I have seen in the manuals, to do a wire splice, to cut the insulation about 1/2 inch off of each wire, mesh the strands together, then solder and heat shrink. Heat shrink obviously goes over the wire first, or one gets to redo the splice.

I have never used this wire meshing/soldering technique, but I will be when I swap the pigtails and fix some other connections that I previously butt connected to get the job done with items available at the time.

What is your preferred solder for this type of wire splice? I know not to get solder up in the wires, just keep it in the mesh area. For some reason if the solder gets up in the wires it can cause the wire to break over time. I don't want wires breaking. Just want good solid connections with very little resistance in each set of wires.

 

[DoubleDingo]

I did some research and it seems that silver flux core is the solder to use.

 

[89Suburban]

These things kick ass fwiw.

https://www.amazon.com/gp/product/B07JJ6YYKL/

 

[Radiohead]

Silver Flux is overkill, just like the new lead free is sheet. If you can find an old roll of 60/40 old school stuff, you will be happy. Finding it is the problem, I, like others, have been hording what we have left. Especially the rosin core stuff.

 

[89Suburban]

And I got this with the recoil heat shield and it works fantastic on those things.

https://www.amazon.com/dp/B08VFY8THD/

 

[75gmck25]

You want to buy solder that is designed for electrical work, not plumbing solder.

Also remember that one down-side of solder vs crimp connectors is that solder by itself does not provide any pulling strength. If you accidentally snag a wire there is only solder holding it together - no mechanical connection.

 

[DoubleDingo]

Silver Flux is overkill, just like the new lead free is sheet. If you can find an old roll of 60/40 old school stuff, you will be happy. Finding it is the problem, I, like others, have been hording what we have left. Especially the rosin core stuff.

I'll check the local mom and pop store for some 60/40, but Lowes does have some rosin core silver in stock just in case. I prefer old school stuff if I can find it, because it is almost always far superior to the newfangled crap.

 

[DoubleDingo]

You want to buy solder that is designed for electrical work, not plumbing solder.

Also remember that one down-side of solder vs crimp connectors is that solder by itself does not provide any pulling strength. If you accidentally snag a wire there is only solder holding it together - no mechanical connection.

These wires are on a fuel rail, and along the bottom of the radiator support, while they are out of the way, they are definitely safe from from snagging in certain circumstances.

 

[SirRobyn0]

I've done tons of wiring soldering and honestly I have no preference or flux. The old 60/40 would be my preference as it use to be the gold standard so it's what I know, but with the modern solder anything that is meant for stranded wiring is fine for me.

@DoubleDingo you didn't ask for it, but I'd like to give you and anyone else some tips. Whatever solder you get find out if it requires flux, I actually will use flux even on solder that doesn't required it, but it's mostly because that's the method I'm use to. Next practice on some scrap wiring first to get the hang of it. There is a technique to getting the wiring hot enough to take the solder and not melting the insulation around it. I'd also really suggest purchasing a good quality soldering iron, some people like gas irons, because you can get one that will get hot fast, and has temp adjustments where as lower cost electrics will take a while to warm up, and only run at one temp, but you can still do some great soldering work with those too. I did for years, until about 6 years ago when I invested $500 in a really nice electric soldering station, at a time we were doing a lot of electrical work at the shop.

IMO, if a guy cannot get the hang of soldering, or needs to join wiring somewhere you can't get a soldering iron, the net best thing is to use uninsulated crimp connectors, since it's just a thin metal crimp connector those can be easily shrink wrapped over.

When shrinking shrink wrap use a heat gun (or even a hair drier) not a cigarette lighter, shrink wrap responds a lot better to the even heat of a heat gun than a lighter which will provide a much hotter more concentrated heat, which risks burning the heat shrink.

As far as the strength, solder vs crimp, if the soldering is done correctly and there is good penetration of the wiring (remember you want the solder into the wiring not just coating the outside), but if the solder is well done the wire will break before the solder will, but if a solder is done to cold, yea it'll pull apart, kind of like welding a cold weld won't have any strength but one just right will be very strong. But there is a learning curve to soldering for sure.

 

[Radiohead]

There's always this...

Western Union splice - Wikipedia

en.wikipedia.org

How to Make a Proper Western Union Solder Joint

How to Make a Proper Western Union Solder Joint: This is one of the harder solder joints to make. When I was in school this was my favorite solder joint. This joint is almost 100 years old and it's history goes back to the days of the telegraph. This was a common joint that linemen would use and w…

www.instructables.com

 

[WP29P4A]

The complete answer is, 60/40 rosin core solder. For what you are doing, a soldering GUN would be the best tool for soldering wires from 20 gauge to 10 gauge. Soldering irons are made for assembling and repairing electronics, not really for butt connecting wires over 20 gauge in size. Soldering irons are very specific regarding wattage depending on the size of the circuit board connections you are soldering. Most soldering irons don't have enough watts to solder 16 gauge wire together properly.

If you are set on using an iron, make sure you go with a higher watt model with a thicker tip. I started soldering in middle school electronics class and have done it on a regular basis for over 46 years, I have used every type of soldering tool made, the best (cord free)soldering iron I have found is the butane type because the heat is VERY adjustable, it will solder 16 gauge stranded wire. Extremely frustrating when your iron almost gets hot enough to solder 2 wires together but all you get is cold solder joints.

The standard Weller soldering gun is the best tool for soldering wires and the worst for trying to work on a circuit board, most soldering irons are the opposite. In my years of fixing what others have attempted I have noticed that people in general make more of a mess soldering than they do using crimp on connectors.

The only two things you need to know to be successful at crimp on connectors/butt splices, is to use the correct (matched) size connector for the size wire you are using and a quality crimp tool instead of the fake crimp tools that most people purchase, just like I did the first time around. The correct tool has a "pin" that creates a crimp that you CAN NOT pull off the wire, to test your crimp all you have to do is pull hard on the wires, if they don't slip or pull out you are now fully capable of using crimp on connectors correctly.

Please stop using the POS crimp on connectors with the colored plastic tube that covers the area of the connector you are trying to crimp, they SUCK and make it harder for the DIY crowd to see what they are doing and make it harder to get a proper crimp, and they look like a clown upchucked fruity pebels all over your wiring. Use shrink wrap. Most importantly like @SirRobyn0 suggested, Practice your technique at your work bench where your comfortable until you are happy with your results before adding the contortion aspect of doing it in difficult to reach places.

I messed up and got the crimper with only one size crimp area and I regretted it when I figured out what I did, buy the one with two sizes of crimp area with 2 pins so you have more options to crimp different sizes of connectors.

FYI the rosin in the solder cleans the conductors and helps the solder to flow, also once wire gets oxidized, good luck getting any type of solder to stick to it.

 

[BRetty]

When shrinking shrink wrap use a heat gun (or even a hair drier) not a cigarette lighter,

Never in my life would it occur to me to use the 12v cig lighter in my ashtray for electrical work.

It *IS* really funny when stoners come up to you parked at the Foster's Freeze or whatever and ask you for a light. One time I said, 'one sec', popped in the lighter element, then pulled it out all glowing and tried to hand it to this guy. He recoiled in horror. Said that his older brother used to torture him with one of those and it freaked him out.

Got rid of that a**hole, at least.

 

[BRetty]

There's always this...

Western Union splice - Wikipedia

en.wikipedia.org

How to Make a Proper Western Union Solder Joint

How to Make a Proper Western Union Solder Joint: This is one of the harder solder joints to make. When I was in school this was my favorite solder joint. This joint is almost 100 years old and it's history goes back to the days of the telegraph. This was a common joint that linemen would use and w…

www.instructables.com

Where's the thread on cable lacing your wiring harnesses rather than using zipties?

 

[WP29P4A]

Never in my life would it occur to me to use the 12v cig lighter in my ashtray for electrical work.

It *IS* really funny when stoners come up to you parked at the Foster's Freeze or whatever and ask you for a light. One time I said, 'one sec', popped in the lighter element, then pulled it out all glowing and tried to hand it to this guy. He recoiled in horror. Said that his older brother used to torture him with one of those and it freaked him out.

Got rid of that a**hole, at least.

99% sure he was refering to a Bic lighter (flame) not a 12 volt car cigarette lighter, but now that you mention it I bet the glowing coil would work great for shrink wrap, just have to work fast. Good memories of Foster's freeze growing up in So Cal back in the 70's.

 

[Radiohead]

The complete answer is, 60/40 rosin core solder. For what you are doing, a soldering GUN would be the best tool for soldering wires from 20 gauge to 10 gauge. Soldering irons are made for assembling and repairing electronics, not really for butt connecting wires over 20 gauge in size. Soldering irons are very specific regarding wattage depending on the size of the circuit board connections you are soldering. Most soldering irons don't have enough watts to solder 16 gauge wire together properly.

If you are set on using an iron, make sure you go with a higher watt model with a thicker tip. I started soldering in middle school electronics class and have done it on a regular basis for over 46 years, I have used every type of soldering tool made, the best (cord free)soldering iron I have found is the butane type because the heat is VERY adjustable, it will solder 16 gauge stranded wire. Extremely frustrating when your iron almost gets hot enough to solder 2 wires together but all you get is cold solder joints.

The standard Weller soldering gun is the best tool for soldering wires and the worst for trying to work on a circuit board, most soldering irons are the opposite. In my years of fixing what others have attempted I have noticed that people in general make more of a mess soldering than they do using crimp on connectors.

The only two things you need to know to be successful at crimp on connectors/butt splices, is to use the correct (matched) size connector for the size wire you are using and a quality crimp tool instead of the fake crimp tools that most people purchase, just like I did the first time around. The correct tool has a "pin" that creates a crimp that you CAN NOT pull off the wire, to test your crimp all you have to do is pull hard on the wires, if they don't slip or pull out you are now fully capable of using crimp on connectors correctly.

Please stop using the POS crimp on connectors with the colored plastic tube that covers the area of the connector you are trying to crimp, they SUCK and make it harder for the DIY crowd to see what they are doing and make it harder to get a proper crimp, and they look like a clown upchucked fruity pebels all over your wiring. Use shrink wrap. Most importantly like @SirRobyn0 suggested, Practice your technique at your work bench where your comfortable until you are happy with your results before adding the contortion aspect of doing it in difficult to reach places.

I messed up and got the crimper with only one size crimp area and I regretted it when I figured out what I did, buy the one with two sizes of crimp area with 2 pins so you have more options to crimp different sizes of connectors.

FYI the rosin in the solder cleans the conductors and helps the solder to flow, also once wire gets oxidized, good luck getting any type of solder to stick to it.

Best answer, highest quality detail. You win the thread. Thanks!