Re: Wire for harnesses

From: Mark J. Blair, NF6X (nf6x@nf6x.net)
Date: Mon Oct 10 2005 - 17:52:14 PDT


bruce C. Beattie wrote:
> Does anyone know of a source for wire used in making harnesses, or a
> substitute that is as
> good or better?

For late-model "M-series" vehicles with non-cloth-covered black wiring,
I've found that Silicone-Rubber Motor Lead (SRML) wire is a very close
substitute. The insulation appears to be a bit thicker, but otherwise
appears to be and feels just like the stuff used in my HMMWV and other
newer vehicles. Although the insulation is thicker, it's soft enough
that it'll still squeeze into the boots on those rubber connectors
(Douglas connectors?) nicely. A little bit of silicone dielectric grease
helps, and also makes the connectors mate more easily.

I get mine from McMaster-Carr, at:

     http://www.mcmaster.com

They refer to it as "High-Temperature Silicone Rubber Single-Conductor
Wire", and it's on page 721 of their catalog at this time. You can type
the page number into the search field to jump directly to a particular page.

Another good item which is available from McMaster-Carr (as well as
other suppliers) is heat-shrink tubing that's lined with a thin layer of
hot-melt glue on the inside. It's good for sealing splices and so forth.
I use the thin-walled stuff on regular splices, and the thick-walled
stuff on things that take more abuse such as battery lugs.

They also supply special butt-crimp splices that are made for joining
two wires of different gauges, or one wire to two wires of the same
size. One of those, covered with adhesive-lined heat shink tubing, and
with the tubing pinched together while still hot between the pair of
wires at one end, makes a nice sealed "Y" splice.

Come to think of it, they also have the military-style battery lugs in
which the cable attaches to a horizontal bolt with a ring lug, and their
price is lower than I've seen from some surplus dealers.

I use high-flex battery cable (AKA welding cable) for battery leads. The
insulation isn't as thick and tough as the original military stuff, and
the cable markings are different, but it's the best easily-available
substitute that I've found so far.

All of this stuff except the Douglas (?) connectors themselves are
available from McMaster, and can be used to make neat, sealed,
professional-looking splices in harnesses of newer vehicles that use the
non-cloth-covered wire. It'll all work just as well in older vehicles,
of course, but it won't look "right" next to the original cloth-covered
wire.

Dang, I just gave away all of my secrets! :-)

-- 
Mark J. Blair, NF6X <nf6x@nf6x.net>
Web page: http://www.nf6x.net/
GnuPG public key available from my web page.


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