Repairing wires

[Dan88]

The chassis loom has been previously cut to fit a new rear crossmember, I was struggling to get 12v so removed all the corroded crimps. I wanted to solder and heat shrink the loom back together, but the wires seemed dirty and wouldn't solder... Is there anyway I could do a better repair or solder the cables after cleaning?

Thanks

[zardos]

You can usually use wire wool to get most of the tarnish of the wires pulling in one direction only (insulation to stripped end).

or you could try using plumbers flux and heating to clean the wire

or clean with something mildly acidic e.g some alloy wheel cleaners contain Phosphoric Acid which should clean the metal

[Pastycrimper]

Is there not enough length to just cut back to the insulation and re-strip and then solder. Certainly re-soldering and properly heatshrinking is the way forward for this kind of reconnection but I'd advise as you've already noted doing this to fresh wire.

[Pastycrimper]

......if not enough length then you could just cut back and insert an extra section of cable. More time consuming but if you solder and seal it well then you'll hav a long term robust fix

[mmgemini]

The best thing about soldering wires to join tham is they become brittle and fracture....

Try cleaning the copper in citric acid or Coca Cola...Make sure you wash the stuff off as both are a good acid.

Then when you've soldered, make sure you hold the loom tight to somewhere either side of the soldered joint.

I

f it was my vehicle, for the cost I'd make a new loom

[g90]

spend a few more pennies and use adhesive heatshrink, well worth it in my opinion, as for cleaning the wires i would use contact cleaner and scotchbrite

[big len]

Are you 100% set on soldering them ? Crimps , when done right , are stronger and last longer. You can get butting crimps with a heat shrink wrapper already on them, one end of the wire in one end, crimp it , same at the other side and then heat to shrink. Adhesive lined ones are also readily available and form 100% watertight joints.

Having said that , if the wire is damaged and corroded it still must be stripped back to fresh copper. But solder should always be a last resort.

[Ally V8]

Have the loom back out of the chassis and sort it out at the bulkhead end.Every loom I have pulled out of a LR chassis has shown long term damage from sharp edges inside the chassis.Put the new loom along the top of the chassis.I use 7 core trailer cable as its well protected and heavy duty.If 7 leads is not enough just run a second length.

[Tanuki]

If the wiring has suffered enough water-ingress for the loom to get black-oxide corrosion on individual strands of the cable, well, basically - it's a goner.

Strip it out and replace the whole thing - It's cheaper in the long run. OK, you can bodge it, but it'll come back and bite you. [i approve aircraft-electrics as part of my day-job: trust me, you won't ever get as far as taxiing your plane if I find soldered joints on aviation wiring-looms]

--Tanuki.

Beware of Lusers: they travel amongst us, and can breed!

[pete3000]

Are you 100% set on soldering them ? Crimps , when done right , are stronger and last longer.

wrong, just more convienient for people who can't solder properly.

Having said that , if the wire is damaged and corroded it still must be stripped back to fresh copper. But solder should always be a last resort.

wrong, solder costs less than crimps and doesn't look like a dogs dinner.

[mmgemini]

wrong, just more convienient for people who can't solder properly.

wrong, solder costs less than crimps and doesn't look like a dogs dinner.

It all depends on who does the soldering...

[big len]

wrong, just more convienient for people who can't solder properly.

wrong, solder costs less than crimps and doesn't look like a dogs dinner.

Wasn't aware this forum had "trolls" ...

[CwazyWabbit]

......

[i approve aircraft-electrics as part of my day-job: trust me, you won't ever get as far as taxiing your plane if I find soldered joints on aviation wiring-looms]

I'm curious as to what is so bad about soldered connections and why crimping is superior, as you perform wiring QA as part of your job I'd be interested to hear what the official reasoning is. Thanks in advance

[ProteuS]

I think it has come up before in relation to crimp on terminals vs soldering terminals for winch cable.

In industrial applications crimping is a relatively easy process to perform and monitor. i.e. set amount of force, tool does a very predictable repeatable action.

Soldering is much more dependent on the skill of the user, and less easy to tell how strong it is without destructive testing.

This is just as I read it, basically good quality soldering is the best, followed by crimping follwed by iffy soldering.

[big len]

I'm curious as to what is so bad about soldered connections and why crimping is superior, as you perform wiring QA as part of your job I'd be interested to hear what the official reasoning is. Thanks in advance

The reasons are three fold:

Firstly the heat involved with the soldering can affect the material properties of the wire, cause it to harden and become brittle - maybe not always on a noticeable scale but enough to cause fatigue issues.

Secondly , a solder joint is complete rigid and solder may even wick up the wire to an extent causing it to also become rigid. Everytime the wire is disturbed where the rigid section ends there is a concentration of stress and this will also lead to fatigue issues. A crimp, on the other hand, is not so rigid and therefore better flexs or however you want to put it to accommodate such movements.

Lastly, corrosion is also an issue for many reason and also due to the small volatge created by two dissimilar metals incontact.

It comes down to this, if a crimp is done right there is nothing better. If it is not done right there is nothing worse. It often amazes me however that many people, in particular mechanics, will spend x y z on a soldering iron and spend time perfecting their technique but scrimp on crimping equipment and give little or no attention to the techniques there in. It should, of course, be the other way round but as is isn't , many many people make a "dogs dinner" (as already mentioned) of crimps and they have this poor reputation in amateur motorsports. I can assure, as tanuki has already said for aircraft, there is not a single soldered wire in any F1 , le mans , paris dhakar and so on and so on

[CwazyWabbit]

Thanks for the explanations.

Is there a sensible and simple way for diy mechanic to test their crimping technique? Is it just observation?

[big len]

Thanks for the explanations.

Is there a sensible and simple way for diy mechanic to test their crimping technique? Is it just observation?

Everyone from the NASA right the way down to the garage hobbiest can use the same test - the tug test. Hold the crimp in one hand, the wire in the other and give it a good sharp tug (okay maybe NASA have some form of machine but to the same effect ... ). Don't hold back on it either , better it break now than later.

Generally speaking though you shouldnt use the crimps that have a simple hollow cylinder that you place the wire in an crush it - they are useless. Start to use the crimps with the proper tabs , two short wider ones in the middle and two narrower longer ones at the back (they are also cheaper). They are a bit harder to use but there are videos on youtube and guides on google that will point you in the right direction. You will get to the point that 99% of your crimps are passing the tug test and the other 1% aren't an issue with your technique smooth and quick. Only thing left to do is to pass on the good news to everyone else

[CwazyWabbit]

Cheers

Are the crimps you are describing the ones with no insulation and form a B shape once crimped when looked at end on?

[big len]

Cheers

Are the crimps you are describing the ones with no insulation and form a B shape once crimped when looked at end on?

That the ones.

The other "insulated" type crushing type ones are to be avoided. But not to be mistaken for the solid crimps that would use a crimps tool that crimps like the shutter on a camera pushing in on around 8 points around the crimp. Those crimping tools are £300+ but are the mutts nutts are far as crimping goes - we have them in work for deutsch type connectors

[Retroanaconda]

Good guide on crimping from our very own Superpants:

http://www.instructables.com/id/How-to-Make-A-Quality-Crimped-Joint/

[pete3000]

Len didn't mean to offend but initially pitching in and saying soldering is a poor substitute compared to crimping, without any evidence made me react. Having read through your reasoning I can agree crimping when done correctly......

i.e with the correct calibrated tools, correct gauge and type of wire and correct size crimps by someone with experience in a production evironment would be a good choice with the right application. However I wonder if these variables and costs are a step too far for the average home mechanic.

Good crimp tools cost an arm and a leg and generally don't lend themselves to many types of crimps. In production environments must be calibrated regularly.

I have crimped my fair share of 38999, suhner, radiall and amphenol connectors over the years, and made properly they are great. However with so may unknowns on landrovers, age and history of wiring, wire gauge, decent crimp availability/cost and the poor selection of crimping tools available for the home mechanic I can't trust crimps over solder. If I must use crimps I will, but never to splice smaller gauge wires.

If soldering is good enough for alternator armature wiring and starter motors I am sure my loom will be fine. I have used crimps on my battery cables with a hydraulic crimper and new wire of a known gauge with new crimps. I didn't solder these as the insulation would have peeled back with the heat on the size of cable.

Don't know if anyone saw the european space agency programme on quest last week, they spent ages arguing about american wire gauge vs european crimps sizes delaying the programme, and resolved it by dropping small offcuts of wire into the crimp bucket to pack them out, to acheive a decent crimp. This brings in what Len said about checking a sample for pull out strength.

Soldering has another useful side effect on vehicle wiring, if the stripped wire is so dull or blackened that the solder won't wet or tin the wire after cleaning the copper is likely brittle and degraded to the point of being useless. The only option is to strip back until you find good wire, or rewire.

Or you could just crimp it, and hope for the best.

[DagdaNI]

i use crimps and i solder at work i would say solder is best when done right but crimping (also when done right) is a close second,

when traceing wiring faults it does seem to be crimpd connectors that are a the root of things but i guess its because someone taking the time to solder will take the time to insulate and secure the wiring

[Quagmire]

See here:

http://workmanship.nasa.gov/lib/insp/2%20books/links/sections/201%20General%20Requirements.html

and here:

http://www.hq.nasa.gov/office/codeq/doctree/87394.pdf

[Maverik]

Here's my tuppenth.

I put a trailer socket onto my 86 original loom. i found the trailer spur all taped up and out the way, when I opened it up, as I've found with many parts of the loom, the copper wire has oxidised mainly due to damp ingress 9goes a nasty black). Its not really cutable back either as over the last 25 yrs its preyty much all the way up the insulation.

You can asses the wires for yourself, but in my case I just used some cause sand paper to clean up the wire before I soldered/heat shrunk the new trailer socket on.

Problem with crimping an old wire is the original oxidisation problem. to get a good crimp you need a good contact, hence scrub it with sand paper, doing this gets you a good contact, butthen makes a rough surface that that promotes oxidation even more and with old wire I've found more often than not that its harder to get a good crimp than it is to clean and solder it. You have to be careful with the heat as you can melt a lot of stuff if you're not careful.

Copper wire is work hardened when its made due to the die drawing process of the wire. Putting heat into copper does not make it brttle, it has the total opposite effect, when you heat copper you are annealing the metal, causeing it to "soften" up.

When playing with old copper wire i doubt you will really see any effect of heating on it, its just generally quite delicate when exposed and after you've cut isulation back and generally bent it about a bit.

Only if the wire is in a really sensetive place will I not solder. - its a good skill to have, so if you can't solder and have a bit of time, try it and get good.

Crimp connects can get you out of trouble, but in my humble opinion, my soldered joints will never get me into trouble

Mav

ups - a little longer than I first intended!

Edited March 4, 2012 by Maverik

[Dan88]

Thanks for all the answers guys, all comments and opinions are gratefully received. Still unsure how to fix my problem though it's between heat-shrink crimps or flux, clean and solder with heat-shrink over that...