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Wiring and connectors

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Paul Mills 408/04/2022 11:35:16
4 forum posts

Need to do some rewiring on a couple of old motorcycles, and not for the first time , no problem actually doing the wiring but these are going to be used in all weathers and from past experience I know that after a couple of months exposure to road conditions, salt and vibrations the connections between the wire and terminal will start to fail. In the past have tried many types of joining these solder, crimp etc.

Thinking about the possibility of something like spot welding, and have seen what appears to be this method on some oem japanese harnesses but have no knowledge of where to start or what equipment I would need. Does anyone have any suggestions?

Clive Steer08/04/2022 12:07:18
100 forum posts
5 photos

For the man in the street I think the best method of making reliable and consistent electrical connections is by using crimp connectors. The high pressures generated when crimping cold welds the copper wire strands together and to the crimp terminal to form a gas tight joint which prevents joint corrosion. Using heat shrink tube to cover the joint should prevent water/salt etc wicking up the wire strands.

The flux needed for soldering can cause wire corrosion and the heat needed can cause the copper strands to become hardened and cause failure when flexed.


Oldiron08/04/2022 12:12:10
996 forum posts
40 photos

I agree with Clive. A good crimp should last a lifetime if the open end is shrink covered


Speedy Builder508/04/2022 12:17:34
2653 forum posts
219 photos

There are also some epoxy products for sealing electrical joints.

Paul Lousick08/04/2022 12:24:16
2078 forum posts
727 photos

Google, mini spot welders. Used for welding terminals on batteries.

A Smith08/04/2022 12:41:36
85 forum posts
4 photos

Some of my bikes have wiring looms that are more than 60 years old, they have soldered bullet connectors. The ignition, lights and charging circuits on my 1960 G3 seem to working well. I don't recall seeing any flux related brass/copper corrosion. In contrast, I helped a pal change the regulator on a CB250 Superdream, every crimped connector was an ugly mass of greenish- blue corrosion. The corrosion had tracked back up the loom for more than an inch in some places. Much cutting, extending & crimping required.


SillyOldDuffer08/04/2022 13:00:17
8898 forum posts
1998 photos

A good crimp creates a cold weld, which should last well. A bad crimp could be due to a mismatch between the type of connector / wire / crimp tool, or maybe the pliers make it hard to get the pressure right?

The cheap crimp tool I started with didn't work reliably so I replaced it with one costing twice as much. The new one has a less wobbly hinge and cleaner anvils. The 'feel' is better and the crimps it makes are mostly good, less than one in 12 being unsatisfactory, with better results if I pay attention!

Quick look at Screwfix, shows my 'expensive' crimp tool is also cheap compared with what's available!. I suspect expensive pliers with a well-made hinge, stiff handles, and well-shaped heavy anvils are easier to use.


john halfpenny08/04/2022 13:51:56
253 forum posts
24 photos

I do a lot of auto wiring. If you can afford it, get a hex crimper and the appropriate bullets. These give a very strong, all round crimp. Otherwise, I would solder.

Paul Mills 408/04/2022 21:59:06
4 forum posts

The only crimps I have seen are aluminium and with copper wiring there is the problem with galvanic corrosion leading to a mess at connections (as Ive not found a reliable way of keeping out moisture) and while I have seen soldered connections that are nearly 60 years old showing little sign of corrosion any soldered connection I make have always suffered from corrosion after a short whiles exposure to the elements and road conditions. The bikes are a BSA ,a New Hudson and a Xj Yamaha and are or will be used all year round .the BSA has had an aftermaket harness fitted which started to give problems after around a years use , the New Hudson will be started from scratch, and the Yam harness is starting to break down after around 30 years use. The terminals on the Yamaha harness appear to be spot welded and it was this that I was hoping to replicate

Think I'll have a look at building a battery terminal welder and see if I can get it to make a strong connection, seen a few designs on the web that may work but thinking I'll have to make it heavier duty and possibly a variable setup to cope with the difference in metals.

Mike Poole08/04/2022 22:50:02
3380 forum posts
77 photos

wiring will be damaged if it is exposed to winter weather, crimping and soldering are both effective but I believe a good crimped connection is many times more reliable than soldering. Having made your choice of connection I would focus on positioning connections out of reach of the weather and where they must be in vulnerable locations then make them as waterproof as practically possible.


Martin W09/04/2022 01:09:57
921 forum posts
30 photos

To get better water proofing of joints/connections etc. there is always adhesive lined heat shrink. Provided it is applied to smooth surface cables i.e. round or oval shaped and not figure of eight configuration it provides a secure and totally waterproof solution even in extreme conditions. Another solution that is slightly less elegant but which can be more convenient to use is self amalgamating tape, again this, if properly applied, provides a totally waterproof solution where cables etc. are joined.


PS To make reliable crimp connections make sure the exposed tails are clean, match crimp to wire diameter and use the correct crimping tool that doesn't release until the crimping jaws have closed. The cheap flat sided plier like 'do it all' tools should be avoided like the plague

Edited By Martin W on 09/04/2022 01:19:31

Martin Johnson 109/04/2022 07:21:46
154 forum posts
1 photos

An associated problem is where to buy decent terminals of whayever type. Ebay is awash with tin foil rubbish, but decent gauge stuff is rare. Any suggested sources gratefully received......

Thanks in advance,


Clive Steer09/04/2022 09:07:03
100 forum posts
5 photos

Farnell or RS components sell good quality connectors, wire, crimps and crimping tools although they are not cheap.

Aircraft component suppers such as LAS sell aviation quality connectors but these will be much more expensive.


Martin Kyte09/04/2022 09:28:44
2794 forum posts
53 photos

Vehicle Wiring Products should sort you out with most of your needs.


regards Martin

Clive Steer09/04/2022 09:30:40
100 forum posts
5 photos

Aircraft crimp connectors can be bought from LASaero. The knife disconnect terminals are good for connections that only need to be disconnected occasionally.

Farnell sell the Deutsch range of multi-pin connectors often found in car wiring harnesses. These are well sealed but current carrying capacity is not high.


bernard towers09/04/2022 09:32:59
691 forum posts
141 photos

Solder every time plus a rub over with ms4 grease.

john halfpenny09/04/2022 09:38:03
253 forum posts
24 photos

Some widely advertised (cheap) brass bullets are too hard. They solder fine, but crack when crimped.

John Doe 209/04/2022 10:42:03
100 forum posts
15 photos

Just to add my 2p and echo what others have said. In a previous career I used hexagonally crimped connectors at work, (video leads at a television broadcaster), and these were very robust and reliable. However, the tooling and the connectors were not cheap. The crimpers used jaws specific to the connector and cable, with different parts of the jaws specifically machined for different parts of the connector. You selected the correct jaw set for the job you were doing and fitted those jaws into the crimp tool.

The professional crimpers and jaw sets cost hundreds of pounds, but they did a very good job, and doing dozens or scores of cables at a time, for live broadcasting situations, we couldn't have failures, and the tooling paid for itself.

Soldering can make good joints, but there is potentially more to go wrong : the wrong solder composition for the job, the wrong soldering technique, the wrong iron temperature, contaminants on the wiring, the wrong flux for the materials, heat damage etc. etc. As has been mentioned, glue-lined heat shrink sleeving applied over a crimped or soldered connection is good protection and insurance against the elements getting into the finished joint.

Like anything in life, if you go cheap and use "toy" equipment and products, you will not get good performance or reliability. Companies such as RS components are the real deal, and have been in business for years. It is very easy to select and order from RS. We all like a bargain, but with an online auction site from unknown, anonymous sellers, you have no idea what the quality or source of the items is, or even if they are genuine parts at all.

My bottom line is do I want to spend time building something that might fail prematurely because of cheap "toy" components and tools, and then have to take the whole thing apart and rebuild it again properly; or would I prefer to do the job properly in the first place so that it lasts. Depends on the job of course.

If you divide the cost of a good quality tool or component by the number of years it will last for, say 10+ years, it does not seem so expensive when looked at from a price per year point of view.


Edited By John Doe 2 on 09/04/2022 10:50:16

SillyOldDuffer09/04/2022 11:02:26
8898 forum posts
1998 photos
Posted by Mike Poole on 08/04/2022 22:50:02:

... crimping and soldering are both effective but I believe a good crimped connection is many times more reliable than soldering. ...

That's what years of industrial experience confirm.

Solder is excellent unless vibration is present. Two causes: solder temperatures tend to harden copper, making it more vulnerable to fatigue failure. The effect is tiny, but shows up when long leads are vibrated over long periods; worse, solder tends to wick between the strands of flexible copper wire, creating in stress concentrators that break the strands one by one. Again, vibration is required.

Crimping avoids both problems, plus dry-joints, and flux corrosion.

In electronics, soldered joints are the best way to fix small components to a printed circuit board. Nothing moves much even if the board is vibrated, and it's not difficult to stiffen boards with pillars and fit foam pads. However, wires often aren't soldered to plugs and sockets. It's partly because long wires tend to flap and break at the connection. Old school reduced the problem by lacing wires into bundles and clamping them to the chassis, but this isn't practical with ribbon.

As always, the need to apply best practice increases with time, volume and circumstances. A soldered joint on a classic bike kept for display rather than ridden regularly would probably last forever. Doing the same on a production run of a few hundred thousand bikes sold to hard riding customers would cause avoidable breakdowns and a reputation for poor reliability.


Dave Halford09/04/2022 11:46:41
2093 forum posts
23 photos

The old bullet connectors that went into the sleeve joiners will be failing because the sleeve was quite heavy and especially liable to flap around on bikes without rubber engine mounts. If you must keep these for the sake of originality the sleeves need tying down to the frame. You can get Velcro tape for this, it looks like old cloth tape unlike cable ties.

BT used Silicon grease filled crimps to prevent corrosion in street cabinets, you can get tubes of said grease from B&Q in the plastic plumbing section.

Resin cored solder never gave any trouble, however the modern 'non acidic' flux for lead free solder certainly causes rust and greens up copper nicely.

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