A bit of Wiring 101

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flingdingo

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It seems like the official FABO winter project for 2021 is rewiring your car. A lot of folks have been asking wiring questions over the past couple weeks so I thought I'd try a bit of a how-to.

I'm rewiring my 64 Dart wagon after it decided to melt most of the underhood wires into a big mess. I've rewired about a dozen cars over the years, most of them while working at a BMW restoration shop.

Let's start with crimps. A good crimp is the basis of a solid wiring job, and a bad crimp will have you chasing gremlins and tearing out what's left of your hair.

Here's my basic tool kit for crimping Packard 56 style connectors:

20211212_224504.jpg


From left to right; ratcheting and non-ratcheting crimpers; small, sharp cutters (yep, I call 'em dikes too) and a decent stripper.

And for reference, here are the terminals we're dealing with:

20211212_224642.jpg


The Packard 56 or double-crimp terminal. The bottom crimp holds the insulated part of the wire, while the top crimp grabs the bare copper.

I'll start by making a crimp with the non-ratcheting pliers. Mine are Mac Tools, they cost about $45 when I bought them sometime in the late 90's. They work on 12 gauge up to about 20 gauge wire, and as you can see in the picture they are designed so the jaws stay parallel when they open and close.

20211212_224523.jpg


Step 1 is to strip the wire. You only want to remove about 1/8 inch of insulation, like this:

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Notice that the insulated part of the wire stops just before the top crimp,, and the exposed copper is just the length of the top crimp.. You don't want a ton of wire hanging out of the top of the crimp like this:

20211212_225746.jpg


It looks ugly and your boss will yell at you.

And you definitely don't set up the crimp like this:

20211212_225757.jpg


The advantage to this type of terminal is the bottom crimp into the insulation provides all the strength, allowing the top crimp to just make the electrical connection.

Oh yeah, if your strippers cut the copper strands like this:

20211212_231511.jpg


Get better strippers. In 18 gauge wire, each one of those strands carries about 15% of the total capacity of the wire.

Anyway, I like to grab the terminal in the crimper first and then insert the wire.

20211212_224909.jpg


If you look closely you can see the "buttocks" side of the crimper on the left. The open side of the terminal goes toward that side. The buttocks roll the ends of the terminal around and in, grabbing the wire like this:

20211212_225007.jpg


I chose the 'B' size to make the initial crimp. And to form the crimp onto the bare wire, go with the next size down.

The biggest problem with these pliers is that you have to guess which size will work best for the crimp you are about to make, so you often have to redo the crimp with a smaller size. But eventually, we end up with a good crimp:

20211212_225139.jpg
 
Boy is this tedious on a phone. Oh well,, now let's use the ratcheting crimpers. I bought these at the L.A. Roadster Show from one of the electrical vendors, I don't remember who. It may have been Painless or American Autowire. They weren't that expensive, around $35 or $40.

These pliers don't release until you've squeezed them all the way, preventing (in theory) bad crimps. In the picture they are squeezed about 1/4 of the way.

20211212_225337.jpg


See the little trigger just above the grip? That's the safety release. If you do screw something up, you push that and the pliers release, so you don't have to waste a terminal on a crimp you know will be bad.

These pliers make both crimps at once and also have the jaws labeled according to wire size:

20211212_225309.jpg


Which speeds up the process and answers the question of which jaw to use. Although I will often start the crimp with the next size up and redo it with the proper size, especially if I'm in an awkward position.

As with the other pliers, I grab the terminal first:

20211212_225410.jpg


These jaws do not open and close parallel, so take care to get the terminal in the jaws square:

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It's extremely common to have the terminal twist as you close the jaws:

20211212_225618.jpg


Which will give you a bad crimp. If the terminal twists, use the safety release and try again.

Once you have it right, insert the wire (make sure its in all the way) and squeeze.

20211212_225450.jpg


You should end up with a proper crimp:

20211212_225552.jpg


I'll talk about barrel type terminals tomorrow. It's late and my typing finger has gotten really tired.
 
I always struggle doing these. No one has ever explained that to me before. That helps a lot, great explanation. Thank you
 
I realize you were illustrating crimping, but.....................

Be careful.............That packard terminal is NOT correct for many types of Mopar connector bodies. Many of them MUST have the kind where the side edges curl over and not the part which folds down from the top edge. This thread................
Packard 56 Terminals?

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Some connectors DO use the "folded over" style...........

upload_2020-5-12_17-56-7-png-png.png
 
Something I've noticed with using those kind of crimps is the tip of those crimping pliers have kind of a flat spot to them and you can put the terminal end flares there and get them started in their bend towards each other of course not too much but just a little tiny bit and sometimes I come just a little bit flared outwards away from each other so when you do put them in the pliers they start curling and towards each other easier but again don't get carried away and get them really pointing at each other yet till you get the wire in there.. and also I've used the flat spot of the tool on the end once they're done to sometimes if they don't curl over tight enough to just crimp them down flat a little bit more but again this is a finesse thing...
I've dealt with a lot of American Auto wire catch and they always come with a little packet of connectors for practice and it says it right there on the pack.... Well using them for practice try not to use them all if you don't have to because you'll find no matter how good you are you'll always screw one up and be glad you had an a spare...
 
All New M&H Harnesses take all the guess work out, and with quality fitting, and precise units to save your car from Fire and more!

I love the Tutorial and tool explanations , But it was obviously done with newer wiring harnesses!

50+ year old wires never looked so nice to terminate rest assure! We all know the Green and Black we see when we strip back the 50 year old insulation! Just Saying!!
 
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