Technical Soldering automotive wiring

On all of my projects I crimped and soldered. On straight on joining of wires I wrapped the wired together and soldered the connection. I've been doing this for years without problems, that I know of, guess I've been just lucky. Never had anyone tell me I was wrong but I also didn't go out of my way to mention it to anyone.

In my business I can terminate 100-200 wires a day, most terminate into terminal blocks, either screw type or spring clamps. I also have to assemble multi conductor MS type plugs with solder cups. These connect to tend to have vibration like machine centers and presses. Plus the cables disconnected occasionally and are in oily conditions, a ral endurance test for wires and wire connections. In over 30 years of doing this type of work I've never had a failure, that I know of. Again, maybe I'm lucky or really good at what I do.

 

I always solder. It's only brittle if you use the wrong connectors, no strain relief or you can't solder properly. Too much heat for too long and the solder wicks down the strands.

Solder fast, and use flux

I also use heat shrink that comes with a hot melt adhesive inner to finish the job

 

I wonder why it is that in some industries, crimping is allowed, but soldering is not? Could it be that it is difficult to verify the quality of a soldered connection, but easy to verify a crimped connection? And that it has nothing to do with the reliability of either connection when it's done properly?

There are still a lot of things that are soldered in industry...for example, every printed circuit board. Billions and billions of them.

 

Most people don't realize that solder wire ends and crimp are different. The solder type has a crimp below the barrel that attaches to the insulation to stabilize it from vibration. It is always amazing how some people resist doing a job the right way and will defend their right to do it wrong.

 

I agree with you that crimp connectors are UGLY, but I've had many soldered connections break right behind the connector that left me stranded. I think there is too much vibration from the road that breaks the wire off. But then I have a couple million miles under my belt in my personal vehicles over my lifetime...

 

Using crimp connectors with heat shrink insulation makes a nice looking terminal IMO

 

I have always been a solder and shrink wrap kinda guy. However, I read somewhere the acid from the solder will cause corrosion over time. True or not...I dunno.

 

Never used solder for connections in 4 decades as an electrician, but have seen soldered joints that caused issues I had to fix. Especially on lower voltages like all automotive wiring works at! Solder after a connector is fine as it wont create any resistance, but soldering instead of using a connector sure will. I don't solder connectors myself, whether they're butt splices, or ring/forked terminals. I actually try to avoid butt splices as much as possible simply because it's one more possible connection issue.
Like some others I heat shrink most connectors, using non insulated connectors to keep them smaller and cleaner. A properly crimped connector shouldn't hurt the wire at all, and makes a very good low resistance connection.

 

Ex Air Force A&E mechanic here, I recall a incident in Fla where a oxygen vessel exploded while servicing a F102 and took out a bundle of about 75 wires, I was tasked with the repair, Manuel said crimped connecters OK. no shrink wrap just good solid crimps bundled back together.
Tool was so good when discharged I took it with me.

 

Don't solder connections. Crimp them PROPERLY.

Soldered connections should be limited to printed circuitry in cars, like the auto manufacturers do.

 

This is one of those perennial arguments...I'm a retired electrical engineer, and in industry we always used crimp connectors or terminal blocks since soldered connections can potentially fail from vibrations, but in real life I think it all comes down to the skill of the installer. Either method will work, if you can properly make crimp connections or properly solder wires.

 

and in real life, I see a lot more failed crimp connections by folks not doing them properly

 

I was always a "solder guy" until I acquired the proper crimping tools. Hunt : You need more than one and they aren't the "sheet metal" ones you used to get at the hardware store with a box of cheap terminals.

 

I never use solder. I was told years ago not to do it by someone that knew more than me. I have always crimped all my connections and used shrink wrap. A good friend of mine strips the end of the wire and wraps it around the terminal! I can't seem to get him to change. He has been doing it for years. That would keep me up at night.

 

Difference there is the equipment stayed on and at a fairly continuous temperature for years on end. Solder joints typically fail with heat cycling.

We have several offices that are alongside heavy machinery routes, and the constant vibration eventually caused the 66 punchdowns to vibrate loose. We changed to wire wrap pins which have a similar pressure on the square peg to round wire joint as a decent crimp does, and those haven't failed.

Solder joints on a vehicle is a wholly different environment to a CO...

 

That's probably because so few solder things ...

 

Well, this has been discussed before, but I have to put my twos cents in, even though I’ve been told I’m doing it wrong, old habits die hard. I started soldering joints some fifty years ago and have never had one fail!
I first crimp my terminals, with a dimple crimper and twist wires the “ Western-Union “ style . Then I solder it, with good solder and the right size soldering iron . Then I heat shrink it.
I maintained a fleet for thirty years , this way , with no failures attributed to my connections.
I know it’s been said I have been doing it wrong all these years, but it has proven successful for me. And most of these connections were on vehicles with diesel engines, that idle a lot.
I will continue to do it my way, but I have quit recommending it for other people.
The one thing I hate and I see it on some otherwise nice cars is, those poorly crimped insulated terminals! I never use insulated terminals!





Bones

 

I'm a belt and braces guy. Crimp & solder. Fully tinned marine wire for big cables, solders so nice. Most of the connections I have fixed have been corroded crimp connections. I can't remember fixing too many soldered connections that had snapped off. If one did, it was because the harness wasn't done correctly and strained the connections. I have worked on automotive, marine, race cars and boats, motor homes, man lifts/rental equipment, heavy trucks and off highway. Like has been said, either can be done to last. Wires snapping off from strain is a harness install problem. I like solder for corrosion resistance, the mechanical is there for when the wire melts the solder from a short or something. Mike

 

Only if you use the liquid zinc-chloride stuff they use on sheetmetal. The roll type 60/40 with embedded flux is inert. Clean it off with iso-prop if it bothers you.
Soldering is like welding - if it's done right, it's fine. Working with the stuff for over 50 years I have seen some terrible soldering which was everywhere, a lot done in the actual factory. You can visually inspect a solder joint- shiny, clean, good wetting and flow, etc.

 

When I first started wiring control systems my boss came in the shop and started pulling on wires to check the connections. He digged on a wire and it came out of the wire end. I was using the ship's tools. The crimping tool was a store bought piece of crap. My boss told me to find a better tool. I found a racheting type crimper that had aircraft approval and have been using that type for over 30 years, never had a wire come loose. I tube on every termination I make no matter what kind of termii.

 

It's simple; it's a life safety issue. Mechanical connections, whether it's a wire nut, crimp, terminal strip or bolted lug will survive conditions that a soldered connection won't, i.e. high heat and some vibration. Add in the fact that the manufacturers of these mechanical connectors will guarantee their integrity when installed as per directions. Not something easily done with solder connections. Having an unskilled installer and an inspector who doesn't know what they're looking at (and that's more common than you think) leaves the door open for problems.

Having a possibly energized (with lethal voltage) wire come loose and flopping around isn't something anyone wants to see. And all of this applies to electrical systems as opposed to electronic systems.

Electronics are a different kettle of fish. Here you're usually dealing with non-fatal voltage and/or current limited (>50 MA) circuits where life safety issues are nearly nonexistent. In the cases where that may not be true, their usually enclosed in a grounded metal enclosure preventing any contact. But even here there are exceptions. Fire alarm systems for example will have solder connections in the control panels and devices, but all field-installed connections are required to be mechanical to guarantee the integrity of the system because this is a life-safety issue.

Hey, if you gotta solder, go ahead. I've never said it doesn't work if done right. But it isn't 'better'. Difference in resistance through a crimp vs a solder joint will require a laboratory to measure, there's literally no difference as a practical matter. Adding solder brings a couple of possible 'fail factors' to the table and it's more work to boot. Why would you do this?

 

Crimping also brings some fail factors. Not many guys building cars have specialized crimp tools and are trained to select the proper parts for the task. Get the size wrong, the crimp fails. Happened to me on the pre-built part of a Painless harness years ago, the headlights were flaky, they had bad crimps, wrong size terminal for the wire used.

An experienced solderer will always know when the solder is flowing and making a good connection. You can see it. You can't see if a crimp is solid.

You can give every crimped terminal the "pull test". It's a good thing to do!

I crimp almost everything on car stuff I work on. But I won't tell guys not to solder things, because I know it has just as good a chance of working, as crimping.

have fun

 

That's the crimp tool I use almost all the time. It does work well. I still pull test each one.

 

15 years in military avionics. We had massive shaker tables to vibration test everything. Crimp connectors with right tools and methods are best. But, for that level of performance we used $15k wire strippers to ensure we did not nick even one strand. Crimping with poor tools is not as good as a proper solder joint. Pick a method you can afford and learn to do it well. Budget tip: Shave a sliver of hot glue stick and put that in your shrink tube. It will seal like the expensive dual wall tubing.

 

One of the first things I was taught about electrical connections is they must be mechanically strong. Solder is not a way to add strength, it only binds the connection.

Not to sure what the problem is with removing the cheesy blue insulator. I put the fitting in a vise and the plastic piece pulls right off using diagonal cutters.

I prefer to crimp and heat shrink a lug to a wire.

 

Have any of you used those butt connectors that look like crimps but you don't crimp them? After joining the wires you slide this thing over the joint and heat it like shrink wrap. They show guy pulling on them and look secure. I bought some, unless I am doing it wrong, they are garbage.

 

On even number days I solder connections and odd number days I crimp them. I then put 8 layers of shrink tube, followed by liquid electrical tape followed by electrical tape followed by split loom. Never had a failure yet.



I say do whichever you’re more comfortable with. I’ll say it again, maybe why so many folks never finish a project car.

 

Does anyone have a link to a really good youtube video or two on the correct way to crimp etc. I have to rewire my coupe next winter and want to get it right.