Soldered Joints, Crimped Joints

I wanted to get some of your thoughts on wiring joints. I’m not talking concourse correct, factory wiring here. I’m talking automotive wiring theory with new wire and terminals. I’ve read a lot of differing opinions on soldering vs crimped connectors. Many laud the strength of soldered and heat shrink tubing covered butt connections and splices. Others point out the properties of the rosin core that can cause oxidation of the copper wires and promote proper crimp connections with quality crimpers and terminals/butt connectors. Then there’s the insulated vs non insulated discussion and the adhesive lined vs plain heat shrink tubing. And the dissenting opinions go on and on.

Personally, I like my butt connections and splices soldered and covered with heat shrink tubing and my terminal ends crimped with non insulated terminals also heat shrink covered. I figure if I cover a soldered butt splice immediately with a good heat shrink, it’ll prevent or slow oxidation enough that I’ll never see an issue in my lifetime if done correctly.

I’m also one of those guys who can’t leave well enough alone. Almost every time I get a “new” old car, I rewire the entire thing with a universal harness, recreating the factory wiring scheme but with fresh wires and more modern methods and way more circuits and relays for more consistent voltage and the ability to easily expand. This allows me to run various terminal blocks inside the car, under the hood, in the trunk, etc. I’ll also have the ignition switch trigger relays for ignition, and accessory feeds to extend the life of the factory switch. And I enjoy rebuilding the original Packard connectors with new terminals.

Anyone have any additional advice and tips. I’m no professional, but my hobbyist experience is enough to get me into trouble for sure.



Edited by Red20 - Mar/26/2018 at 3:06am

My theory has always been crimp for mechanical strength, solder for electrical conductivity and corrosion protection.  I know that solder has a much lower conductivity than copper (about 1/5th as I recall) but if you take into account the typical solder thickness in a soldered joint there isn't much difference between the solder and the copper/brass.  Heat shrink, only the adhesive/marine/waterproof version. 

bigbad69 wrote: Crimp joints are perfectly fine if done correctly. The crimp should create an air-tight joint between the wire and the terminal. This requires practice and a good crimping tool to achieve. The manufacturers of crimp terminals invariably make a crimp tool for each terminal design, and the tools are not cheap. You can get away with the cheap dollar store crimper, but it is much more difficult to achieve the air-tight crimp. Allowing air into the joint promotes oxidation of the wire surface, which is an electrical insulator.

I remember my first crimp with a set of decent ratcheting crimpers. I was amazed. And I recently came across a stash of really high end avionics crimpers that I need to get proper does for ($$$). I can’t wait to try those out. Some Burndys, DMC HX4s, and others.

Older strong acid based products and misconception:

1. They are noncorrosive at room temperature
2. Rosin type flux is hygroscopic and can act as an insulation
3. They normally cure at room temperature to entrap potentially corrosive activators"

The truth is that either crimps or solder, if properly done, will work fine for our hobby vehicles and likely outlast us anyway!

All that being said, I have a friend who is a P.Eng Electrical engineer with 25 years experience and according to him, crimps are air tight, avoid flux, conduct better, don't have heat damage to either wire or insulator and are the preferred method of military contractors. Electrically superior and mechanically stronger.

Take that as you see fit!

Chris