Lotus Elan

Wiring tools

PostPost by: tonyabacus » Wed Nov 18, 2020 11:46 am

Saw the article about crimping tools a couple of weeks ago and wanted to pass on what I used when installing my new harnesses.
I agree the bullets really need securing to the plastic covering which is not easy with most bullets, however Vehicle Wiring Products in the UK (see website) do a crimped bullet that allows this to happen as it provides for crimping the copper wires as well as the outer sleeve. However I would recommend using something like the correct Ripaults (mines quite old now) crimping tool which effectively folds the sides of the terminal over and forms what might be loosely a "W" shape and really tightens down on the wire. If you can imagine, the bottom jaw has a "U" shape and the top jaw a "W" shape, so as they come together the two work to fold the sides whilst tightening the grip on the stranded wires, then you can do the same on the sleeve making a secure fit, hope that makes sense. Most of the cheaper crimping tools are made for the plastic coated pre insulated terminals and do not have the "W" pattern jaws and just squeeze the connector which does not always provide a tight fit.

Also the pre insulated terminals are a slightly bigger size than the non insulated type of bullet which can lead to poor loose connections if reusing the sleeves, so better to replace both bullet and connector sleeve. Where the old terminals have been replaced by these pre insulated bullets they force open the connector sleeve resulting in this sloppy fit. If you take the plastic outer cover off a connector sleeve, you will see some small indentations on the inner metal part so that the bullet when pushed home clicks past the end of the bullet to hold it secure.
Pre insulated bullet 5MM o/d
Non insulated bullet (like originals) 4.7mm o/d

Next getting the bullets into the sleeves, there is a special type of pliers for doing this which are quite expensive, but if you have some adjustable pipe wrench pliers where they open out on a ratchet type of arrangement, these can be used to carefully squeeze the two bullets into the connectors and are a lot cheaper than the dedicated tool if working to a budget.

From Vehicle Wiring Products website, I have no connection with them but not many others stock these type of bullets, I have not included the squeezing tool but it is on there,
1. MP71 Crimping tool with spring return handles - you can just about make out the "W" pattern in the jaws
2. "W" pattern bullet connectors
3. Preinsulated crimping tool - only good for the pre insulated bullets and not the "W" pattern, so limited value

Apologies, what started as a short response has turned into short story!
Tony
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PostPost by: Elan45 » Thu Nov 19, 2020 6:37 pm

I solder my bullet ends on. A bit of a hold-over from my stage rally days when wet muddy wiring connectors didn't conduct electricity as well as they did when they were clean and dry. I never intend to get my Elan connectors as filthy as we did on the forest stages, but I don't fail them either.

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PostPost by: Bigbaldybloke » Sat Nov 21, 2020 12:11 am

My background is in industrial gas turbines and generators, and offshore oil and gas platform control and instrumentation. Solder is used on circuit boards but never on wiring harnesses and power connections, these are always crimped. Even generator main connections on 16MW generators are crimped. A soldered connection has a higher resistance than a properly crimped one, the main component of solder is tin which does not conduct as well as copper. We used to check connections inside control cubicles where there are hundreds of connections with thermography cameras and on terminal block connectors with wires with crimped terminals on them you could easily see where there was a poor connection. Without fail it was always the screw in the terminal block coming slightly loose rather than a problem with the crimp. If we found a terminal showing warmer than it’s neighbours we would find that the screw would probably tighten between 1/4 and 1/2 a turn and on checking it again an hour or so later the temperature was back to normal. The cameras we used could easily detect a fraction of a degree, to illustrate it we would just rub the carpet with our shoe and you could easily see the rub mark, or just put your finger tips briefly onto a desk top and they were clearly visible as warmer than the rest of the desktop.
Anyway, back to soldering or crimping, in order of quality starting worst to best is, a poorly soldered connection, a poorly crimped connection, a good soldered connection finally a good crimped connection is best. Soldering a connection that has already been crimped can improve a badly crimped one where the wire strands are not all secure, but badly soldering it can make it worse if it is overheated and too much solder added such that it runs up through the crimp and into the cable outside the crimp. This makes the cable stiff and brittle if subjected to vibration and regular movement. There is also the flux to be considered, flux can be corrosive and should be cleaned off once the joint has cooled.
Having said all that my front wiring harness that I have custom made to go with additional fuses, electric cooling fan , alternator etc., is mainly crimped but in a couple of places does have soldered connections, so it’s all personal preference, basically use a good quality crimp tool and crimps or use the right size soldering iron and rosin cored solder and you shouldn’t have any problems.
The one thing that never gets mentioned is the insulation stripping tool. Many of them can score or partially cut the copper wire strands which immediately weakens the cable just beside the connector and this is the place where many wires fail. A good wire stripper of the correct size for the cable is worth it’s weight in gold for good reliable connections.
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PostPost by: gav » Sat Nov 21, 2020 11:01 am

BBB

That's very interesting.

Thanks for sharing the knowledge

Gavin
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PostPost by: StressCraxx » Sat Nov 21, 2020 4:40 pm

I'm in a very similar business to BBB, oil refining. The only soldering present is on circuit boards. Everything else is crimped. We also use a thermal sealing heat shrink tube on crimp connections wherever possible, to keep moisture and corrosion out. We are in a salt air environment along with traces of sulfur in the air.

We also use IR inspection for our electrical equipment and airborne ultrasonic for medium 4160 and above and high voltage 12KV and above to detect the crackle of corona discharge. Ultrasound will detect a developing poor connection months or even years before damage is done.

I have a Crossle Formula Ford. It vibrates, much more than an Elan. Crimped connections only, for the reasons given above.

BTW, if you are interested in a relatively low cost IR imaging kit, I bought this for my work several years ago. It connects to a smartphone. Very useful for troubleshooting a dead cylinder, cooling system issues or hot connections. I used it on house and found a couple of air/heat leaks around windows and door frames, and used it to verify the integrity of electrical work performed on my house. https://www.flir.com/products/flir-one-pro/
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PostPost by: The Veg » Sat Nov 21, 2020 4:58 pm

I mis-spent some of my youth in the US Army, where I trained as a repair technician for mobile RF communications systems and did this job for my entire four-year enlistment. Part of the training was a week-long course on soldering. One of the things that was emphasised in that course was that solder is a poor conductor, as has been stated above in this thread. The main purpose of solder is structural. We were trained to ensure that the conductors in the joint had the best physical contact that they reasonably could, and THEN solder the joint to hold it in that contact. Based on this, if a crimped connection is well and good and properly done, adding solder could be of structural benefit (adding strength, keeping corrosion from forming between the wire and the terminal). Just remember that that's all it is.
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PostPost by: tonyabacus » Sat Nov 21, 2020 9:51 pm

PB217858.JPG and
Crimping Tool jaws
PB217858.JPG and
Crimping Tool jaws
Interesting points made about crimping v soldering by people who have a lot more experience than some of us.

The problem in part is that most of the bullet connectors do not enable you to clamp the outer sleeve, which on some of the very fine cables means it can be difficult to get a tight bite on the wires. That is where the Vehicle Wiring Products "W" bullet connectors come into their own. Also I believe you may be able to improvise with a pair of pliers, punch and hammer if you don't have the correct tool. I have not found another supplier of these terminals so if anyone knows of another supplier it would be useful to post it.

I finally got a picture of the jaws on my Ripaults tool and have posted it so you can see how the jaws create the "W" tight connection. As you will see these are different to the tool you use on the insulated terminals you get these days.
Hope the picture comes out clear enough to see what I have tried to explain.
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PostPost by: Bigbaldybloke » Sun Nov 22, 2020 1:15 am

Just to elaborate on the comment by stresscraxx above on heat shrink, not sure how many people know this but you can get adhesive lined heat shrink. The adhesive melts when you shrink it on and forms a permanent joint which should be completely waterproof. Disadvantages are that it makes a very stiff joint that basically doesn’t bend. Also it’s very difficult to strip off once shrunk on unlike ordinary heat shrink which can easily be cut off. Probably only useful if you need to permanently extend a wire that is too short or has been damaged and you need to replace a section of straight cable.
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