Originally Posted by mechanicalmoron

Good god, crimped shit, in a fucking airplane?

That has got to be one of the scariest thoughts I've ever had.

Crimped connectors will fail for metalurgical reasons, LONG before solder will. Crimped connectors will vibrate off, when solder will NOT. Crimped connectors can pull out, when solder can NOT.

If you are getting it hot enough to melt solder, you are getting it hot enough to soften crimp connectors. It's also hot enough that there will be no insulation, all your wires will be on FIRE, your engine bay PAINT will be on fire, everything will short. Your whole damn car could be on fire, before you need to worry about solder melting.

Solder has more surface area, and should make a better connection on those grounds, though I don't know how much resistance it has.... but it's used in precision electronics, it can't be THAT bad. Nevertheless, resistance, in some situations, MIGHT justify crimp connectors, I suppose. And maybe in some very specific locations, like right on a turbo, a crimp would make sense... is the insulation on that wire asbestos, or rubber? If rubber, solder is the better choice.

Originally Posted by thefro526

I'm going to preface this post by saying that I'm no wiring master or anything, but have a bit of experience with it.

As far as the solder vs. crimp thing, this is a topic debated among EE's to this day. In reality, as long as you're conscious of the loading that the connection could and/or will see, either method will work with proper planning.

If you ever have the chance to go through an OEM harness in a 'safe' environment (as in, you don't need the harness to be in the car to get to work or something the following day) I suggest you go through it and look at how some of the stuff is done, it's actually really, really cool.

There are a handful of connections in the OEM Harness that are both Crimped AND Soldered, for some interesting reasons. When splitting a single wire into multiple runs, let's say something like taking a single 10Ga wire and splitting it into two or three, a crimp makes physically holding the wires together so much easier, and is also going to bare a significant portion of the physical load. From there, adding solder to the crimp is going to ensure that you have proper conductivity between the wires, but isn't actually going to see much of the loading that the 'joint' may see. The solder also has the added benefit of acting like a 'glue' - think of what would happen to the wires in the crimp over time, after a while, the crimp could loosen leading to some sketchy connections.

It's also worth bringing up pinning and re-pinning connectors while we're on this topic, since this is hands down the 'right' way to do any sort of harness work. In a perfect world, instead of adding additional wire or removing it to do your tuck, you'd figure out how long the run is and remake it using new pins and wire. Then you know that you only have two connections in the system (one at either end - the pin/terminal) which is going to minimize the failure points, essentially keeping it the same as OEM.

Regardless of which connection method you use, one of the most important factors in the reliability of ANY wiring is strain relief. You never want the wire to be loaded at a connection, and you never want the wire to be pulled into a really tight radius. A lot of guys that do their own wire tucks at home seem to make this mistake at least once, and it's a pretty easy one to avoid. Look at any motion in the system when planning your wire routing, and be sure that there's some slack in the wire around that motion point so that the connector/wires/connections are never being pulled on.

The other thing to be conscious of is heat and how it can effect a connection, either soldered or crimped. Solder being quite obvious, if it gets hot enough, it'll melt. Odds are, you're going to have issues before the solder melts though, more often than not, insulation on 'standard' wire will melt well before solder actually does. Crimps are also susceptible to heat, but they're rarely thought of as being. Figure that as the crimp is heated, it will expand, which can cause it to loosen and fail. Personally, I've never seen a failure like this first hand, but it's something to be aware of. TLDR to the heat thing is to use properly rated wire or looming for the application and keep connections away from heat sources.