Wiring harness splicing - Soldering or Crimping Method

Question

I need to rebuild the injector harness on an old vehicle using Y-splices on the wire to reduce cable usage/lengths (V12 engine).

My question now is how to to the Y-splice on the wires.

• Soldering
  Seems to be discouraged for automotive use, because stranded wire gets stiff and breaks under vibration. Also high temperatures on top of the engine makes solder brittle.

• Ultrasonic welding
  Seems to be the professional choice - no access to such a machine tough.

• Crimping
  I´ve seen a lot of bad homemade crimps - i´m not sure if it is doable with non-professional tools. However, this seems the way to go. Still need a way to join 2 wires

  • Butt Connectors
    they don`t seem to be designed for putting in 2 wires on one end.

  • Crimping Tubes (Aluminum) Found them at a rc hobby supply store - but they are not intended for (stranded)wire use at all

  • "Scotchlock" Type
    They are intended for automotive use; however i don`t consider this a permanent or even sufficient electrical connection.

Which method and tools should i use? Or is there a better way?

Answer 1

A properly soldered connection should not break due to vibration. NASA uses soldered splices in their wiring harnasses. See: https://workmanship.nasa.gov/lib/insp/2%20books/links/sections/407%20Splices.html

Answer 2

I have repaired many wiring harnesses with soldered joints (made the joints very slim so that the repair looked as per original once taped up - no bulges etc) both in the engine bay and under the dash.

Soldered joints do not have any problems and, done properly, will have a lifetime longer than the vehicle. However, if you let moisture get in there then you will have corrosion issues, but you can get corrosion issues from wet wiring anyway.

I would seriously suggest that you avoid all those "crimp" tzpe connectors shown in the images - they will all let in the moisture...