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nelmo

Joining Wires

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And if you haven't been stranded at the side of the road with a wiring fault you haven't really had a trip, have you??

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Once you get the hang of soldering, it's a better joint.

 

Twist the wires together first. Strip about 3/4" from each and twist in line (don't make a V joint) and remember to put the heat shrink on FIRST (Even I forget this sometimes :) )

 

Tip to soldering. Make sure that the iron is up to temperature and that you wipe clean the tip (a wet sponge quickly swiped is enough) and have a bright silver coloured tip.

 

Apply just a touch of solder to the iron which assists in heat transfer. Now apply the iron to the BACK of the wires and touch the solder to the FRONT of the wires. When the wires are hot enough, the solder will melt and be drawn toward the heat. I.e through the wires. Remove iron and do not wiggle the joint until is has cooled and solidified or else you risk a dry joint which looks dull grey. It should look shiny when finished. Slide the heat shrink on and use a heat gun on it to shrink it. If you try the soldering iron to shrink it, you run the risk of melting the wrap or burning it.

 

Don't apply too much solder or else it will wick along the wires making a longer stiff section which can fail later. Don't make joints around corners but make sure the join is as vibration free as possible.

 

Saying all this, these joints will last the life of the car and more.

 

Scotch blocks - NO ! :)

 

Simon.

 

Edit - Also make sure that there are no bits of wire sticking out once soldered and the joint is smooth (you can use pliers to crush these if you're careful) as these will punch through the heat shrink if you don't remove them first.

Edited by Simon B
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For the more adventurous builder! If I'm joining two wires of the same thickness in an area where I don't wont the loom diameter to "grow" because of the joints overlapping each other I do the following.

Each stripped end (typically about a cm) is twisted about 90 degrees clockwise. Then the two end are offered up to each other, then I gently untwist the wires so that ends splay all the strands open slightly. Next, rather than wrap them around each other I feed one splayed end into the other keeping the untwisting tension on (as it where) then I re-twist both ends and pull on the wires slightly. With practice the 2 ends grip into each other and make a joint that is barely thicker than a single wire. Then I solder the joint as neatly described by Simon B. Then I remember I forgot the heat shrink!

You can also join into an existing wire this way as well. The down side to these joints is you can never unsolder the buggers easily to fit the heat shrink you forgot in the first place!

Apart from the thickness of the joint being better than a typical twisted joint you can get away with a shorter joint as well.

 

Where I use a multi pin connector block, providing the wire is sized correctly for the connector I'm more than happy to use just a crimped connector which technically is very slightly better at resisting long duration vibration (hence its use in aerospace and the military). Where, for whatever reason, the wire is not the right size for the pin in the connector I'll crimp and solder. I've lots of wires pulled out of a crimped connector because it wasn't matched properly, soldering solves that issue.

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Malcolm has described a " married joint" damned near perfectly -- it is what we used in overhead line jointing ( decades ago ) & I taught in college with maybe limited success; correctly done it will be stronger than the cable & not much bigger in diameter.

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I can tell you military spec uses solder into a multi pin socket most of the time...I can say the same about my Emerald set up, crimped joints with solder or into a multi pin plug.both are covered in tape too. If it's done correctly both work well. Never let me down.

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What I'm getting here is that both ways will be fine, although soldering needs more skill (which I don't have).

 

Many thanks for all your posts - very enlightening... :good:

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Both Soldering and Crimping done right will be serviceable for years, as pointed out soldering can be susceptible to vibrations, but if supported/ loomed correctly should give no issues. Again as already pointed out the crimp joints weakness is moisture, but most cars don't see the rain, most have more water during washing than rain they see in a year!

 

I have made a couple of wiring looms for F2 sidecars outfits that have been round the IOM TT without issue, one even got a trophy! They were fully soldered and heat shrunk.

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The trick to soldering well is having clean a soldering iron tip and clean wire. Don't leave the tip too long as the flux residue will burn off and spoil the job. Best to practice on some offcuts first. You'll quickly get the hand of it.

 

Note though, do NOT breath in the fumes. They ain't good for you :) I usually find myself slowly breathing out while making joints as it helps blow away these fumes.

 

Simon.

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OR! tease bare cable into 3 equal groups of strands, both pieces and then splice together like rope and then solder all together similar to Nasa one but I think if not stronger ! was taught this in my first year as an apprentice 52 years ago !! :crazy: mick

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Good qualitly through crimps, that are see through so you can see wire position in the crimp, crimped with corect crimping tool not a universal, then heat srink with corect size heat srink, this alows for the wire to be left straight without any bends.

 

Best pratics it not to crimp or solder but to have continus wire.

 

Bomb crimps are designed to insolate a cable core that can not be removed, not to joint 2 wires togesther.

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When I was on my apprenticeship I worked at a place near Heathrow wiring plugs for the then new swing wing aircraft test gear,my job was to wire up these plugs,the cable had 25wires in it the plug had 25 pins in them the plug was about 30mm /40 mm dia each pin had a wire soldered on to it then heat shrink slid over the joint had to use a special glasses to see what you were doing and steady hands ,must of done it right cos none failed after they were tested to aircraft standard

Peter2b

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all these techniques for joining wires together makes for good reading............but hands up how many have just twisted 2 wires together and insulation taped over the top at the side of the road lol......... :rofl:

Edited by steamer
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Not on a car......but once or twice indoors maybe

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all these techniques for joining wires together makes for good reading............but hands up how many have just twisted 2 wires together and insulation taped over the top at the side of the road lol......... :rofl:

Seem to remember a certain S.A. person needing that "repair" a few times in France.

 

Always carry some "choc blocks" & a clean pair of u/pants may be a good motto.

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