Proper Splicing

AkursedX · Post by **AkursedX** » Fri Jan 18, 2008 11:31 pm

I thought this article might be useful to the more novice mechanics around here like me. I'm not a fan of wiring and I never have been. But this year I decided to learn how to do things properly and solder connections together.

In the past, I have used barrel crimp connectors that have the heat shrink wrap on them. They have worked fine but I know it's still not the best. So I bought myself a soldering iron and some heat shrink tube and am going to wire things right this year!

ANYWAYS.....I wanted to see what proper splice and tap soldering should look like and I came upon this site:

http://www.mmxpress.com/technical/connections.htm

I found this to be quite enlightening and hope that someone else will find it as useful.

whipped · Post by **whipped** » Sat Jan 19, 2008 12:29 am

That's the method we were taught in school :thumbleft:

I'm surprised people still use butt connectors.

The Dark Side of Will · Mon Jan 21, 2008 10:34 am

Solder is actually rare in the aerospace industry.

REAL butt splices are no joke... they get their bad rep from the discount crap you can get in auto parts stores.

Real butt splices, for instance, use seamless tubing and work for only one gauge of wire.

Aaron · Post by **Aaron** » Mon Jan 21, 2008 11:55 am

A friend who now owns my maroon car taught me how to solder, and it's how I did the harness in both of the 3.4 swaps.

I bought an automatic wire stripper from a store for like $10, and thought it'd suck. It is almost honestly the best tool I have. It saved me SOOO much time and aggravation, I would pay triple what it costs. Go get one, they are amazing.

Then I'd strip about a half inch off each wire, then spread the independent strands inside of the actual wire. I'd put the to wires together, and twist their strands together. Then I'd hold it up with the soldering gun, and wait until the wire was hot enough to where it pulled the solder through the connection.

All of my solder joints were just perfect, this method worked extraordinarily well. It was also pretty cheap, as I only needed solder, the $10 tool, and the heat shrink tubing that is like $2 from Lowes.

Pyrthian · Post by **Pyrthian** » Mon Jan 21, 2008 11:57 am

yup. heat shrink tubing is your friend. and - remember - put it on BEFORE you connect the wires

Aaron · Post by **Aaron** » Mon Jan 21, 2008 11:58 am

Pyrthian wrote:yup. heat shrink tubing is your friend. and - remember - put it on BEFORE you connect the wires

He makes a good point. I can't count on both hands how many times I forgot :cussing:

Kohburn · Post by **Kohburn** » Mon Jan 21, 2008 1:22 pm

regular heatshrink is ok btu it will still allow moisture to wick in, and it does little or nothing for the physical strength of the splice.

i only use environmentally sealed crimps. they are all we used for the aerospace and marine applications at work. once you crimp them, then heat them the heatshrink had a glue inside that softens and bonds to the wires insulation. it made the splices stronger than the rest of the wire and you could completely submerge them with no risk of corrosion.

whipped · Post by **whipped** » Mon Jan 21, 2008 3:00 pm

Aaron wrote: Then I'd strip about a half inch off each wire, then spread the independent strands inside of the actual wire. I'd put the to wires together, and twist their strands together. Then I'd hold it up with the soldering gun, and wait until the wire was hot enough to where it pulled the solder through the connection.

You know how the professor tests a splice connection? He pulls the wires (hard) before it is soldered. If it comes apart before the wire breaks, it's a bad splice.

Aaron · Post by **Aaron** » Mon Jan 21, 2008 3:11 pm

whipped wrote:
Aaron wrote: Then I'd strip about a half inch off each wire, then spread the independent strands inside of the actual wire. I'd put the to wires together, and twist their strands together. Then I'd hold it up with the soldering gun, and wait until the wire was hot enough to where it pulled the solder through the connection.
You know how the professor tests a splice connection? He pulls the wires (hard) before it is soldered. If it comes apart before the wire breaks, it's a bad splice.

Mine would have surely pulled apart, but I couldn't have avoided that. It already was hell on my hands each night, they would hurt so bad from twisting the wires and such.

But the harness in the maroon car has been working great, daily driven through Colorado and Oklahoma weather, without any issues. And the black car's hasn't had any issues yet either, so I think it's good enough :thumbleft:

p8ntman442 · Post by **p8ntman442** » Mon Jan 21, 2008 5:46 pm

Wire should not be subject to tesile stress. The Professor was showing that you could do that, but its not by any means necessary.

whipped · Post by **whipped** » Mon Jan 21, 2008 9:43 pm

The point was that you shouldn't rely on solder as the mechanical bond.

Blue Shift · Post by **Blue Shift** » Tue Jan 22, 2008 3:00 am

Hell, I painstakingly lap soldered every last connection in my wiring harness, then used heatshrink tubing. It's just a quirk of mine.

I strip a little more than 1/4" of the insulation off each end, twist the strands together neatly so they don't fray, and fully tin both ends. Then I use 4 fingers on my left hand to very carefully hold them end to end, and side by side, and flow solder till solder flows around both wires and cools, usually burning myself in the process. I unspool some solder from the roll and use it as its own "3rd hand". Once the solder is cooled, the wire will break long before the joint separates. Pain in the ass and inefficient but it looks neat to me. :la:

Xanth · Post by **Xanth** » Tue Jan 22, 2008 9:55 am

Thanks for the link, helped quite a bit while working on my stereo install. :thumbleft:

I'll probably end up pulling my remote-start back out and redoing the soldering now that I know what I was doing wrong, didn't get the wire hot enough for the solder to flow through, just kinda lumped on there.

Series8217 · Post by **Series8217** » Tue Jan 22, 2008 12:35 pm

On a harness I built at WCF I used good butt splices, soldered the wires into the crimped splices, then sealed them with heat shrink that has a melting inner liner. That heat shrink tubing is awesome. It provides a completely waterproof seal and also helps hold the wires together mechanically. Those joints will never fail!

Kohburn · Post by **Kohburn** » Tue Jan 22, 2008 3:31 pm

Series8217 wrote:then sealed them with heat shrink that has a melting inner liner. That heat shrink tubing is awesome. It provides a completely waterproof seal and also helps hold the wires together mechanically. Those joints will never fail!

thats the best stuff you can use

The Dark Side of Will · Tue Jan 22, 2008 4:11 pm

Share a brand/supplier?

Emc209i · Post by **Emc209i** » Wed Jan 23, 2008 1:56 am

I did at least 50 butt splices two weekends ago on my DOHC harness. Once you get going, things move along swiftly. I have a knack that these high end atmospherically sealed connectors cost bank.

Please share links to superior connectors.

Kohburn · Post by **Kohburn** » Wed Jan 23, 2008 9:38 am

if buying the sealed crimps then mouser.com - i believe you can get the sealing shrink wrap at most west marine stores.

Kohburn · Post by **Kohburn** » Wed Jan 23, 2008 9:41 am

if buying small quantities they are something like .50 to 1.00 each.

they are especially handy splicing in places you would never try to get solder in.