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Soldering 'old' wires


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Need some general maintainance this back end on my 50 plus year old wiring,

New lucar connectors etc.

 

Anybody any tips on cleaning the copper strands that often have resin on them now that prevents

Good soldering, I was thinking a decent flux or soldering fluid?

 

John

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Hello John, if you want it to last another 50 years you are better crimping, solder goes brittle with age and cracks and flux is quite corrosive, cheers, Andrew

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Crimp v solder brings out two distinct camps. We've talked about it at length here.

 

I'm a crimp proponent, too. Well-done, gas-tight ones that is. Not the kind done with handyman pliers.

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You get a higher incidence of wire fracture with soldering. Works best if there is some strain relief.

 

I'd never use acid flux with electrical work.

 

Old wire needs cleaning by mechanical action. Scotchbrite is very good on cable. Scalpel is the way for thin wire.

 

You will need a higher temperature and more heat on a wire with poor solderability. Unfortunately this tends to fry the insulation.

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Within the last month, I have had to replace both connections to my generator (originally a dynamo, but alternator since 1993) because the soldered connections to both the large and small Lucars had cracked. Replaced with cable which will withstand much higher temperatures (it gets very hot down there near the 4-branch exhaust, despite the heat shield) and crimped Lucars, for which I have the proper tool.

But I have used soldered bullets for additions to the wiring in areas where there is no movement.

 

I am reading the book on the BMC Competitions Department, and I note that Stuart Turner praises the special wiring undertaken by Mr Smith from Lucas, and I believe, from what Graham told me, that the same fellow undertook the wiring of the Works' TR4s - and he did a splendid job as this is the first occasion on which I have needed to replace any of his wiring.

 

Ian Cornish

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Anywhere where a connector will get hot, or get splashed, or suffer ingress of dirt or water, Crimping is a better option, especially if you have a suitable covers for the connectors . For bullet connectors inside the car, I solder them, but if I had a good enough crimping tool, I would crimp them too.

 

No matter what connections are made, after 50 years they will be suspect!

 

When soldering grubby ends of wire, if you have enough slack, chop the end off and create a new soldered joint. Even then the wires may have become corroded, and as Andrew said, scraping the wire with a dull blade works pretty well.

 

TT

Edited by tthomson
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Which ever method is used to make connections the newly bared flex strands are likely to be darkened from age. So which ever method is used to make connections it would be prudent to brighten them before bonding.

I grip the newly stripped ends in a fold of 600 grit wet and dry and pull it out a couple of times.

Crimping is only as good as the tool used to make the bond. Soldering requires a little more skill but can be just as reliable as a good crimp and a poor solder joint is most likely longer lasting than a poor crimp.

A common problem for DIY types is to use an iron/bit which is too small. A small iron doesn't have the thermal capacity to make a quick joint.They are not as effective as a slightly cooler larger one and take longer to transfer sufficient heat. Long contact times causes the issues which are mentioned above. If you can't make a joint to light car flexes in less than 2 seconds then your technique or tool is not right, There is plenty of stuff on You Tube showing how its done,The flux in current electronic/electrical grade solder wire is less corrosive than the types used in the 1950s/60s. (but which as said have lasted 50 years).

 

Mike

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So no one knows a "magic" method.

 

You clean the wire with some kind of mechanical method.

Very tedious if you have a lot of joints but no problem on one or two.

 

I do a lot of chemical cleaning of metal.

All the processes I use will leave a surface that looks "clean" but there is a surface layer which won't solder well.

 

If you had Silver plated wire then Silver-Dip would do the trick but I don't know an equivalent for Tin.

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Hello, I have two crimp tools, a 'proper. one bought when I was more flush than I am now, a £160 Knipex tool bought for £80 in a sale and a £20 knipex one of Ebay, they both give good results, I bought them as it is far easier to do a proper crimp than get a proper solder, particularly if you are upside down!, cheers, Andrew

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For solder you must clean the copper wire to remove any corosion

The wire needs to look like new..shiney copper finish

And the next important bit is to have the correct size iron...too small and you are not going to get the solder to take

If this is not achievable then go down the crimp route but you still need to get the wire clean

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On the boat, which goes into a salt water environment, I replaced any non 'tinned' wire with the tinned stuff. Some of the inherited wires were 'black' up to several inches from the joints.

For the black stuff in other situations, I use hydrochloric acid to take the crud off when the gentler fluxes fail to do the job.

Not a fan of crimps, on the Prado most have failed after a number of years due to corrosion.

But if it works for you go for it.

Edited by littlejim
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Almost nil use of soldered connectors on aircraft. All done by crimping.

 

The reason is vibration. At the point where the solder stops penetrating between the strands there is a point of weakness. The soldered part is stiff, the rest isn't. If the cable is not restrained then this is where you get fractures.

 

This is why a "bullet" is pretty satisfactory. They support the cable insulation quite well.

 

Now on a boat everything will get salty wet. And maybe the solder waterproofs the joints quite well. And probably not too much vibration.

 

I have wiper-motors, best part of 60 years old, seen a lot of wet service by the inside of them. The solder joints are usually fine. It's the enamel coat on the windings that goes, the cotton-covered stuff is the worst.

Edited by AlanT
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Since many years I use Electric Contact Spray... I learned it from our airport technicians. It combats damp and cleans wires from any corrosion.

These days I treat all electric connections every year with the spray.

 

As many mentioned crimping is the way to go, If you are handy a tiny drop of solder would keep the strands together but avoid it penertrating upwards into the isolation.

I use tie-raps where ever vibrations might occur, wires hanging around are a serious hazard... :(

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Just to be clear: Never crimp a soldered wire. Solder creeps under stress and so the crimp will loose its airtight seal properties leading to early failure in service

[i believe Jean recognised that in his advice about not crimping on the soldered area.]

 

Mike

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