What model terminal crimper will crimp these double wire crimps?
Delphi PDF Catalog: delphi.com/pdf/contact/brochures/DCS_GlobalCatalog.pdf
Their crimper tools are on pages 378-379.
Model No: 12040070 is the only one that mentions “doubles”, but sells for $90 and has limited usefulness, since I won't be crimping many doubles. I'd prefer one to do both doubles and singles. I’ll be using it for wires 0.35 - 3.0 mm^2 (possibly larger on future jobs).
I've used kits similar to the S&G, they work great on just about any size wire or terminal.
However, 99% of what I crimp is done with one of these. I haven't had any problems yet.
Even with double wires, if you twist them together first you shouldn't have any issues with the crimp.
I'm sure that by twisting them together you can get a great crimp on the copper core, but how about the insulation crimp?
The insulation crimp is important as it places the fulcrum on the insulation, instead of the more brittle core. I've seen plenty of problems (often intermittent) caused by bad insulation crimps, although they had great core crimps. The copper strands tend to bend and break at that point.
If the wire is breaking under the insulation crimp it was probably crimped too tight. Squeeze until you see stars on the wire, but just enough to get it snug on the insulation.
They're not breaking under the insulation. They break on the uninsulated part between the two crimps. This happens more often where the wire harness takes a sharp bend, is in a confined space, or experiences a good amount of movement. For example, i'm currently working on the connectors located between the door and fender, and at least two wires are showing signs of wear there.