Best way to splice a cut wiring harness

[irl]

I recently picked up a 74 wiring harness for my project and it was cut in half at the dash. I usually use heat shrink compression connectors but I have heard others talk about the need for soldering. The heat shrink will keep in permanently in place but does soldering help increase the continuity? Looking for some thoughts.



Thanks!

[Jcslocum]

Soldering with heat shrink will help to avoid any corrosion over the long term. Try to stagger the splices to keep the diameter of the cable from getting 2X it's original size.

[abisel]

^^^
What he said.

Wrap the ends together in a butt splice fashion, solder and heat shrink tubing. And make sure the splices are staggered to keep overall diamter small.

Another option is using crimp butt splices that have a sealer and solder ring that do their job when heat is applied to shrink the tube. Again, stager the splices.
http://www.connectorsupply.com/catalog/crimp-solder-seal-butt-connector-blue-16-14-gauge-p-429.html

[buster1015]

I try to solder and use heat shrink whenever I can. I'm my opinion it's the most reliable method and looks clean too. If you aren't yet an expert with the soldering Iron I found a youtube video that explains exactly what you are looking to do.

How to Solder - The Basics - YouTube

[HawgRyder]

Stagger the joints...and do not twist the wire ends before pushing them together.
Think of it as pushing your fingers together from opposing sides...after you have the wires meshed...twist them very slightly...then solder just enough to keep all the little ends together.
Remember to put a piece of heat shrink on before doing all this...LOL
This method will keep the joint bundle as small as possible.
I would also recommend putting a piece of big heat shrink over the main bundle before doing the joint.
You could even place 2 pieces of the big tubing on (one on each end of the big bundles) with one being just the length of the non-covered area...and then slide the second (longer piece) larger on over the top of it all to grab both ends of the original sheathing.
Hope this helps.
Bob

[Bob Kontak]

That is a job.

Think it through. Note as you start to join up the wires one at a time, the amount of movement in the remaining wires will be less.

I would think to splay the covering wide open on both sides of the break. Lay the wires out on a bench with lots of room and focus on keeping the harness sides in their original orientation so you don't have to reef/twist it around to fit.

Don't be afraid to add sections of new wire between the splices if you mess up. Better longer than shorter. I see nothing wrong with adding a one or two inch section to each splice to make sure you don't pimp yourself over with a too short wire (where it finally connects) . Of course, the work is now doubled.

[304065]

I would get a different harness entirely.

If you solder that, even if you use Raychem solder sleeves like an airplane, the solder joints will be less flexible, more brittle, than a straight run of copper wire. Even if you can solder perfectly. This will allow vibration to fatigue the wires, potentially resulting in fracture.

Fracture is not what you want when hundreds of miles from home, at night, doing the ton. I would just not feel comfortable even if I had done the work myself. There are no solder joints in a factory harness, I've looked.

Since the harness is out and you have to pull a new one in anyway, I would look around for an uncut one and use that.

[dshepp806]

As Bob noted, you'll lose a bit of length with the "staggering" approach,..you sure don't want to end up "tight".

If it were me, I'd go with 304065's suggestion....without compromise.

BEST!

Doyle

[tocobill]

Depending on where the cut is I would use heat shrink bullet connectors and then use a marine grade heat shrink tube over them. Just stagger the connectors so it doesnt bulge to bad. Most marine grade heat shrink tube has a adhesive/goo that while you shrink it will seal the wire and joint very well from moisture. If you ever need to pull the harness again it can be disconnected and puled back out with ease. Soldering joints tend to be brittle. Heat shrink crimp connectors melt and seal the wire pretty well.

Just my two cents ...

[McLaren-TAG]

Keep things in perspective guys, it's a wiring harness in an old Porsche, it's not a new Boeing Dreamliner.

With the exception of twisting and taping them back together, any other professional means you use to join them will be more than sufficient. If you say where exactly the cable runs and if it is subject to any kind of CONSIDERABLE flexing, which none of the harnesses in the car really are, then you'd be fine simply butt connecting all of those wires together.

Like others have said, if you need to keep the cable straight, then stagger the joints. If you have more than enough cable to use, a better way to join them would be to use a butt connector and twist and connect both wires crimped on only one side of the butt, then tape everything shut with 3m tape and then a stout wire tie on the cable end will keep the splices from ever moving. Finito and it will outlive the car... promise.

[Spark Chaser]

This is now the preferred method in the aviation industry. You will have to purchase a crimped though.
http://raychem.te.com/documents/webservice/fetch.ashx?fileid=8460&docId=927

[mrm930]

No solder! Use connectors with crimpers and slide heat shrink over them (before the connection). Stagger the connectors. Or buy 3-way, 4-way, 5-way and 6-way connectors that can be disconnected - but stagger.

Better yet - new wire harness

[mrm930]

Try this site

Electrical

[Justin@Athens]

Lets make this easier; How about wiring two of these up to each side of the harness-- eliminating the need to solder and creating a tidier, easier to troubleshoot connection. Once you are satisfied that the connection is solid, heat shrink the area around the plug where you removed the sheathing and wrap the plugs in electrical tape.

http://compare.ebay.com/like/330861149204?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar#

You can probably find a 20 pin connector somewhere, but I couldn't right off.

[roblav]

Stagger the joints, plenty of heat shrink, and no solder. Most of us racing formula cars have given up on solder because it gets brittle and cracks.

On the other hand, a multiple pin connector is another good alternative. Heat shrink tubing on every wire / connector joint then tubing all around.

[Dave Colangelo]

20 pin connector hands down. Chances are it was cut because it was hard to get out, that means it may be hard to get in, the 20 pin connector will make that far simpler.

Regards
Dave

[dicklague]

the wires in the first photo are NOT all the same gauge. 20 pin connector would not work unless you went to a much larger size....

soldering with heat shrink tubing is best. You can even get a kit with various colors and sizes.

[roblav]

Well.... now that I think about it, I was at the local NAPA looking for some battery cable connectors. They had these real cool connectors where you stick the solder inside the connector, lightly heat it to melt the solder, then stick the wire in it. Those have held up really well on my cars. Maybe they have something like that in 18 gauge.

[mrehrer]

Apologies for jacking but I have a similar dilemma with a harness that does not have quite enough length to the DME to put it in a reasonable location. At the moment the DME rides around in the rear seat but it wants to be under a seat or otherwise out of the way.

Is there a better way to make an extension than creating the original poster's problem above and then adding a third segment of wire in between the two halves?