Quick question about soldering.

Quick question about soldering.

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Discussion

vrooom

Original Poster:

3,763 posts

274 months

Monday 3rd June 2013
quotequote all
I am going to solder new extension wires onto existing wires somewhere on my engine, it's about 10 inch away from fuel rail and is disconnected. so there is little petrol fumes about.

Can I solder safetly as my solder dont create sparks etc.

Mikey G

4,784 posts

247 months

Monday 3rd June 2013
quotequote all
Would be no problem at all as long as you are using an electric iron.

nsa

1,686 posts

235 months

Monday 3rd June 2013
quotequote all
Mikey G said:
Would be no problem at all as long as you are using an electric iron.
Dude said he wanted to solder, not do his laundry.


fluffnik

20,156 posts

234 months

Monday 3rd June 2013
quotequote all
Yes.

... however crimping will provide a better connection both electrically and mechanically.

buzzer

3,558 posts

247 months

Tuesday 4th June 2013
quotequote all
fluffnik said:
Yes.

... however crimping will provide a better connection both electrically and mechanically.
I hear this said... but find it hard to believe. any idea why? I would have thought a pair of wires twisted together and soldered was the best joint?

Mikey G

4,784 posts

247 months

Tuesday 4th June 2013
quotequote all
I have done many many repairs and loom modifications by soldering joints, never ever had a problem. I have seen some really bad jobs though using solder, either by using bad quality solder or just dont have the technique.
I have tried to find nice small 'butt splices' for joining wires but most are too cumbersome to be hidden neatly away in a wiring loom. I also prefer to use adhesive heatshrink on my joints to help with water proofing and oxidising.
Trouble with most modern solders is the lack of lead as that used to give a little flexibility on thinner parts of the joint.
Bigger wires like battery, charging, heavy load items and earth leads should never be soldered, there are plenty of crimps around ideal for these.

fluffnik

20,156 posts

234 months

Tuesday 4th June 2013
quotequote all
buzzer said:
fluffnik said:
Yes.

... however crimping will provide a better connection both electrically and mechanically.
I hear this said... but find it hard to believe. any idea why? I would have thought a pair of wires twisted together and soldered was the best joint?
Solder is comparatively brittle and prone to corrosion and there is more resistance at the copper/solder boundary than copper/copper crimp.

Uninsulated crimps and heatshrink sleeving are the way forward.

ch427

9,742 posts

240 months

Wednesday 5th June 2013
quotequote all
cant see how crimping is superior to solder myself, if you heat shrink your joints correctly then all should be well.
A crimped joint especially without the correct tool or knowledge can be poor

Richyvrlimited

1,838 posts

170 months

Wednesday 5th June 2013
quotequote all
I keep being told this, but have never had a soldered joint fail, yet crimps constantly fail.

Granted I don't own a really high quality crimper which probably doesn't help, but heatshrink over a soldered joint is so much tidier, and if you're making multiple solders on the same loom if you stagger the positions there's no stress in the same position.

fluffnik

20,156 posts

234 months

Wednesday 5th June 2013
quotequote all
ch427 said:
A crimped joint especially without the correct tool or knowledge can be poor
Indeed, decent ratchet crimpers are not expensive though.

Mr2Mike

20,143 posts

262 months

Friday 7th June 2013
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ch427 said:
cant see how crimping is superior to solder myself,
Crimping is a form of cold welding, you get inter-molecular bonding at the junction which gives the lowest possible resistance. You also don't get solder wicking and the subsequent loss of flexibility of the wire either side of the junction which is important in applications exposed to movement and vibration.

On any kind of mission critical system (automotive, trains, space flight etc.) cables will nearly always be terminated by crimp connectors for their superior reliability (if crimped correctly!).

Richyvrlimited said:
I keep being told this, but have never had a soldered joint fail, yet crimps constantly fail.

Granted I don't own a really high quality crimper
That's like saying my soldered joints keep failing so crimps must be better, though I do use an iron set to the wrong temperature and/or an unsuitable solder alloy.

Soldered joints can be fine in the correct environment, and if the cable is adequately supported either side of the joint (so that the solder wicked part of the cable isn't moved) it can even survive ok with some cable movement. However, it's still not electrically as good as a crimp, and it is a longer process, especially on large high current cables.


Edited by Mr2Mike on Friday 7th June 08:45

felixlighter

228 posts

154 months

Saturday 8th June 2013
quotequote all
I personally solder, and never had a problem. I used to crimp small stuff and have had problems with unsupported wires.
The solution, crimp-solder-heat shrink insulation

Mr2Mike

20,143 posts

262 months

Sunday 9th June 2013
quotequote all
felixlighter said:
I personally solder, and never had a problem. I used to crimp small stuff and have had problems with unsupported wires.
The solution, crimp-solder-heat shrink insulation
Then you either didn't make the crimp properly, or you used unsuitable crimps.

andyiley

9,976 posts

159 months

Thursday 13th June 2013
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I have to say, I hear both sides of this argument and would always fall on the side of solder & heat shrink for a few reasons.

Solder joints are alleged to suffer corrosion due to the acids in the flux, i have never come across this, but like others have come across many failed crimp connections.

When you solder a joint correctly you can see that it is correct instantly, in a crimped connection you cannot.

When an aftermarket alarm/imobiliser is fitted all connections must be soldered or the certification will not be valid. (someone in the industry has stated this for a reason & they probably know much more than me)

Just my 2p worth.

Mr2Mike

20,143 posts

262 months

Thursday 13th June 2013
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Have a look inside an equipment cabinet on the side of a railway track if you get the chance. They gets pounded by vibration from trains all day, yet have to be utterly reliable and remain in service for a very long time. You will find every cable is terminated by a crimp connector.

one eyed mick

1,189 posts

168 months

Friday 14th June 2013
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Ultimate reliability ?1 place heat shrink on stripped cable 2fit unins conector to cable3 crimp with a pro level tool4 solder 5 pull heat shrink over joint and apply just enogh heat to shrink , it take patience but will not fail [ if supported properly ]

GnuBee

1,277 posts

222 months

Friday 14th June 2013
quotequote all
Mr2Mike said:
Have a look inside an equipment cabinet on the side of a railway track if you get the chance. They gets pounded by vibration from trains all day, yet have to be utterly reliable and remain in service for a very long time. You will find every cable is terminated by a crimp connector.
Add to that; look at the connectors in your car, they'll be crimped. Take a look at those nice, shiny MilSpec motorsport connectors - all crimped. Connectors in airplanes, tanks, ships yada yada - crimped.

Proper crimping tool and connectors is the key; if you're getting crimping failures then it's only down to poor quality tools or connectors.

andyiley

9,976 posts

159 months

Friday 14th June 2013
quotequote all
GnuBee said:
Add to that; look at the connectors in your car, they'll be crimped. Take a look at those nice, shiny MilSpec motorsport connectors - all crimped. Connectors in airplanes, tanks, ships yada yada - crimped.

Proper crimping tool and connectors is the key; if you're getting crimping failures then it's only down to poor quality tools or connectors.
You talk about using poor quality crimping tools, I am refering to manufacturers crimped connectors.

You say about connectors in planes etc. I think you will find they are actually soldered plugs by preference.

The military also use soldered plugs or direct soldered connections by preference.

andyiley

9,976 posts

159 months

Friday 14th June 2013
quotequote all
vrooom said:
I am going to solder new extension wires onto existing wires somewhere on my engine, it's about 10 inch away from fuel rail and is disconnected. so there is little petrol fumes about.

Can I solder safetly as my solder dont create sparks etc.
What was that you said about a quick question?

There are many opinions about the answer to this question, and I think the answer is to make your own mind up on what is best for your situation as both are potentially good ways of connecting 2 wires together.

Ultimately, the answer to your question is. Yes, it is safe to do.

Mr2Mike

20,143 posts

262 months

Saturday 15th June 2013
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andyiley said:
You say about connectors in planes etc. I think you will find they are actually soldered plugs by preference.

The military also use soldered plugs or direct soldered connections by preference.
I'm pretty sure you are wrong on both counts, but definitely for aerospace applications which are crimped. A properly formed crimp is superior in every way to a soldered joint. A badly crimped termination is a liability that makes a soldered joint look like the best thing since sliced bread.