How to transform a rat’s nest into orderly wiring

In the hierarchy of automotive dreads, rust repair and wiring rank near the top for most people. Rust repair we get, but wiring doesn’t have to be a nightmare. After all, a wire just goes from one place to another. How hard can that be?

The problem is there’s always more than one wire. And those wires connect to things. …

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YOU CAN DO BETTER THAN THIS!

[narrator, watching me do wiring]: It turns out, he could not do any better than this.

Both timely and appropriate as I prepare to make better the American Autowire harness in my own Type65.

Looking forward to the future installments, and thank you for sharing your knowledge and experience

JG Pasterjak said:

YOU CAN DO BETTER THAN THIS!

[narrator, watching me do wiring]: It turns out, he could not do any better than this.

Thus the current Colin conundrum.  I want to do better than this.  It requires a crazy amount of planning, because wiring harnesses look like that when things are added after-the-fact.

I would welcome some tips on thining out  thee harness of my e36 track car, just want push button start, brake lights, fuel pump etc.... thanks in advance, the

In reply to The :

The slow but sure way I have been doing it:  Identify a connector you do not need, cut the connector off of the wires, remove the loom (if it is like the R53, the loom is cloth tape wrappings) and resecure the harness with a few zipties at strategic points, extract the wiring from the loom by PUSHING to find where it wiggles.  Continue until you get to a splice (cut at splice), ground junction, fuse box, or wherever else it terminates.

You will need to re-snug the zip ties on occasion as you thin the herd.  That is why zip ties are nice.  Get big bag and be generous with their use.

Here's a pic I took while I was about a quarter of the way through my current progress.  Almost all of the wires running down the tunnel area are gone except for about seven or eight, for the power mirrors.  Likewise a lot of the ones on the right, quite a few on the left, and I even got it to the point where I was able to re-loom the wiring in spots.

Pete, thanks for the tip, thats kind of the way I was thinking, take out a wire, does the car still run, yes/no go or stay. thanks, the

     The "physical" aspects of wiring... proper crimping, gauges, connectors, looming, routing, etc are great and this article is addressing that part of the job. Will you get into designing a wiring topography that isolates data circuits and their power supplies from the "noisy" side of the car that carries fan motors, ignition systems,e tc ? Also, proper grounding is crucial.

     I bought a Panoz GTS that had been a full-time race car for about 20 years and, along the way, "Race day" repairs had been made to the wiring harness. When I pulled the dash tins off, revealing a bit of a rat's nest, my coach and friend said, "You can just put that right back and walk away", but I knew I could never unsee that. The last thing I wanted on my mind at 165 MPH entering 10a at Road Atlanta was "Man, that wiring is a mess". :-)

      I rewired the entire car from the firewall to the rear bumper, removing old, broken circuits, adding a rain light, a new switch panel and all the "oddities" from two decades of repairs made under the time pressure of getting back into the race.

     Proper wiring, with proper devices and materials, gives me a real peace of mind on track, plus elevates my knowledge of the car.

I have created my own mess.  I wasn't happy with my FFR roadster set up as it came from Factory Five so I installed a good aftermarket generic 20 circuit harness.  I'm now trying to get that looking like the pics on the boards and not having any luck.  So, my fallback position is to sort bundle and remove the excess.  It's this last piece that is driving me nuts.  What to cut? where to cut? Should I be ruthless and eliminate wires that I could possibly need in the future...  ?#*#?*!?   HELP

I don't suppose you guys have the order from your "kit" from Terminal Supply sitting around as an example BOM?

We have found that if you draw out what you want on a single piece of paper, then start removing what is not need in the harness, it goes rather wekk.

YRMV

A trick I picked up from a Formula SAE book a few years ago:

For developing the harness, use twist ties instead of zip ties.  That way, when you inevitably need to move or change something, you can just untwist the tie and make the modification, without having to cut and replace the zip tie.

Then, when you're done changing, you can replace all the twist ties with permanent zip ties.

Another tool recommendation: 

Get one of the zip tie tensioner/cutter tools.  In addition to applying consistent tension, they also cut the excess flush, so you don't have little sharp bits all over the place to slice the back of your hands.

Jesse Ransom said:

I don't suppose you guys have the order from your "kit" from Terminal Supply sitting around as an example BOM?

Ditto. I have a trailer and track car I need to rewire and would love you use something better than the random cheap Amazon/HF/WM connectors I picked up over the years that never seem to work right.

tomtomgt356 (Tommy) said:

Jesse Ransom said:

I don't suppose you guys have the order from your "kit" from Terminal Supply sitting around as an example BOM?

Ditto. I have a trailer and track car I need to rewire and would love you use something better than the random cheap Amazon/HF/WM connectors I picked up over the years that never seem to work right.

I'll try to put something together in the next week or two. Since the story was first written, I've also found some better terminals with double crimps--one on the wiring and one on the insulation for stress relief. Goodspeed Motoring has a good selection. I really like the Dephi 12085271 crimping tool for these types of connectors. I got mine from Mouser. 

tomtomgt356 (Tommy) said:

Jesse Ransom said:

I don't suppose you guys have the order from your "kit" from Terminal Supply sitting around as an example BOM?

Ditto. I have a trailer and track car I need to rewire and would love you use something better than the random cheap Amazon/HF/WM connectors I picked up over the years that never seem to work right.

There are companies that sell the original pins that go into connectors.  As a matter of fact, some of them will send you "engineering samples" that could populate your entire harness.  I did that when I rewired an Alfa, using the original connectors to hold the pins.  

One other thing I would add to harnesses is some kind of cover.  Some of the covers are ugly plastic, but that looks better than you trying to find a short when it wears through to touch the body.

In reply to alfadriver :

I'm a big fan of this stuff:

Wrap-around sleeving

It looks nice, neat and professional, but since it's split lengthwise, if you need to add a wire or two to your harness, it's not a problem.  Obviously it does not seal to the elements, but there aren't many (any?) factory harnesses that are.