Mustang Sallys Land Rover Pages
Making Terminations:
You can do it properly with a few basic tools and the right materials.
Insulated barrel crimp fittings
Making a reliable termination
A substitute for bullet connectors
Extra-good quality Marine Terminals
Insulated barrel crimp fittings
The most common automotive cable termination available in Australia is the insulated barrel crimp fitting. Original pattern Lucas connectors can be had from specialist suppliers of car restoration products but in my view these have nothing going for them except the original look. The insulated barrel type comes in many patterns, including rings, forks, hooks and male and female spades. The rings, hooks and forks are made for various stud sizes while the most commonly used female spade is the 6mm variety which suits the male spades on many auto electrical accessories. However the 4mm female spade is sometimes required, most notably for the connections to the later Lucas wiper motor.
The crimp terminations are made of plated copper and have a split crimp sleeve for the wire end, over which is a copper crimp barrel enclosed in a tough plastic sleeve. The plastic sleeve is colour coded to show the wire size it is intended for.
Sleeve colour
Cross sectional wire size
AWG size
RED
1.5 mm
16 gauge
BLUE
2.5mm
14 gauge
YELLOW
6mm
10 gauge
- The terminals are much more economical to buy if purchased in quantities of 100 of each
size. They may be obtained from specialist auto-electrical stores or from electrical
wholesalers. Here is a link to Auslec/Lawrence&Hanson
who have 200 sales outlets Australia-wide. The average auto parts store will probably only
have them in plastic packs of ten or so which is an expensive way to buy them if you need
them in quantity. Be careful of the quality of terminals in auto parts stores. Some
unbranded terminals can be stamped out of very thin, brittle, poorly plated metal. Some
I've seen have had the crimp barrel under the plastic sleeve made out of tinplate steel.
Some have omitted the crimp barrel altogether! If you are doing a big wiring job, stick to
well-known names and inspect a sample first. In Australia, Quikcrimp and Utilux are good
as is Lawrence&Hansons new "Lanson" house-brand.. Even the name-brand ones
seem to be made in Asia but you can at least be assured that they are made to the brand
owners satisfaction.
- The wire is stripped to length to suit the terminal, inserted into the crimp sleeve and
then the crimp barrel in its plastic sleeve is compressed in a couple of places with a
pliers-type crimping tool. If the wire is the correct size for the terminal, it should now
be held firmly.
- The cheap crimp tools stamped out of thin steel are OK for occasional use. However, the
much more expensive ratchet action professional tool is worth it if you are rewiring an
entire car. The ratchet action is much easier on the hand muscles and the tool makes two
distinct crimps in one action with its two broad anvils.
- Automatic wire strippers are a great invention as they strip the insulation off to your
required length with one squeeze of the handles. If you are careful, the insulation can be
cut with a very sharp small knife or single edge razor blade but there is a risk of
cutting into the wire strands. A $20 wire stripper will pay for itself in saved time on
your first big job and you will still be using it long after the cost is forgotten.
Inexpensive crimpers Expensive crimpers Two kinds of automatic wire strippers
Images used with permission of Dick Smith Electronics. Visit their web site and on-line catalogue for great mail-order service.
Having described the insulated barrel crimp connection, I must now say that I have given up crimping them when making critical terminations. And on a Land Rover used in off road conditions, every termination is critical. I have become concerned about the long term effects of corrosion on a crimped connection. When salvaging wire from defunct wiring looms I notice how the copper conductors can be blackened and embrittled for quite a distance under the insulation from exposure to the air. The crimp barrel connector has no ability to seal the end of the insulation or to seal the crimp sleeve where it grips the conductors. I've heard of owners applying a dab of RTV silicone rubber or even 5 minute epoxy to each end of the crimp barrel but I cannot imagine a slower or messier procedure when making dozens of terminations. Do not misunderstand me; a crimped connection is perfectly reliable in the medium term when made with quality terminals, a good tool and the right sized wire. However, I wondered what they would be like in twenty years so I now use the method illustrated in the next section.
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Making a reliable termination.
You will require the following items :-Terminals as required. Must be clean and bright, not ones that have been rattling about in the toolbox for years.
Heat shrink tubing of a size which will shrink down properly over wire insulation and crimp sleeve.There are several colours available so you can use a simple colour code to aid circuit identification.
Electric soldering iron 30 watt with 2.0mm flat tip OR Butane gas soldering pencil.
Resin-core solder as used in electronics assembly
Hot air gun for shrinking heat shrink.Electric type used for paint stripping is ideal.
Insulation strippers, side cutting pliers, needle-nosed pliers.
Heat proof, non inflammable, non conductive surface to rest terminal on while soldering. A brick or a terracotta floor tile is ideal.
The terminal must have the insulated barrel removed by gripping it with one pair of needle nosed pliers and gently pulling and twisting the barrel with another pair. The barrel can be discarded.
Cut about an inch of heat shrink tubing and slip it well down over the wire so that it won't be prematurely shrunk by the heat of soldering. Strip the wire to a conductor length which will barely protrude from the split crimp sleeve. The split sleeve can be opened slightly with the fine pliers if conductor is hard to insert.
Using the pliers, gently crimp the split sleeve down onto the conductor. Don't just flatten it or it will look terrible under the heat shrink tubing. With care, one edge of the split sleeve will slip under the other edge. Then the second edge can be dressed down on top of the first edge. You want to maintain the circularity and hold the conductor firmly for soldering. It takes longer to describe than to do.
Place the terminal on your brick or tile and firmly apply the well heated soldering iron to the split sleeve. When sleeve and wire are heated enough, apply solder to the end of the wire. Use just enough solder to make a good bond between wire tip and sleeve. Too much solder will "wick" down the conductors to well beyond the split sleeve and create a "hard spot" where the wire strands may flex and fracture at a later date.
When it has cooled down, firmly tug the terminal to test the soldered joint. Slide the heat shrink sleeve up to just past the split sleeve and shrink with the hot air gun. The heat shrink plastic has a matt surface which takes permanent felt-tip ink well. With a fine felt-tip pen you can write code letters on the sleeve as part of your personal wire identification scheme. Just be sure to read the information on your pen barrel to prove to yourself that it is a permanent ink marker, not a washable one.
I've been using up my stocks of crimp barrel terminals but when I need to buy more I'll look at non-insulated terminals to avoid the waste of throwing crimp barrels away.
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A substitute for bullet connectorsThe insulated barrel bullet receptacles do not lend themselves to removal of insulation and soldering. Spade or ring type connectors attach to a spade or stud on a fixed electrical accessory whereas a bullet connector is an "in line" joint hanging in mid air. There is normally more than one of them heading in the same direction so you can select a nylon spade terminal connector block which come in sizes containing anything from two to eight sets of connections. I use one particular "Night Vision" branded type from an auto parts store but I have seen several sorts using different designs of nylon block. All seem to use a standard type of brass crimp spade with a "stake" or small spring nib designed to lock them into the block. Be careful when soldering these as excess solder in the wrong place can make it difficult to get the terminal into the nylon block. The blocks have a moulded latch to prevent accidental disconnection so they are quite secure.
The terminals will take wire up to 2.5sq.mm. and can have heat shrink fitted for looks, air exclusion and support.
They are good for:-
Tail lamps to rear body harness.
Rear body harness to main harness.
Electronic modules such as ignition umits, thermo fan controllers, tachos and alarm systems.
Accessory gauge panels to main harness.
Extra-good quality Marine Terminals
I've never used these but some builders have recommended them to me for use in conjunction with tinned copper marine wire. They incorporate a heat shrinkable sleeve already attached to the terminal which is shrunk down after crimping of the barrel. This type of connector is not soldered as well and the correct crimping tool is essential. Main disadvantge is the cost, up to four times more expensive per terminal. However, they are said to be absolutely impervious to water and atmosphere. One maker is Ancor Marine Grade Products. See LINKS section on Electro Tech page for a link to their web-site and also to the web-site of the Australian agent.
The unattributed images on this page were made by
arranging the items on the bed of my CanoScan FB320P scanner and closing the lid. The
resulting images were then cropped, captioned and otherwise doctored using Microsoft Image
Composer. Believe me, it was a pain! However, they came out quite well considering that I
don't know what I'm doing. If anyone from Canon Australia is reading this, I'd really love
a free digital camera.(Fat chance, but its worth a try)
This page last modified on Saturday, 10 April 1999
