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Harness Making Tips & Tricks


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This thread may get moved into the Tips & Tricks section at some point, but we already have a thread called

Tips & Techniques: Harness work in the Garage/Shop & Tools and then the Techniques section. But it seems to only have info on connectors and I think we need something on making, or re-making, a harness.

We have bits and pieces of ideas here and there, so need to collect them. For instance, in Big Blue's Transformation Jim suggested that "A roll of those little Velcro cable wraps we use in server rooms and underfloor will be your best friend when dealing with that spaghetti monster." And a bit later he said "Get this wire loom Tesa tape while you're at it. It really makes a difference!" Then, in a followup, he said "I use convolute on some runs, braided sleeve is good too, where you don't need protection from the elements. But this is especially good for junctions and wrapping sections (candycane like) inside the plastic sleeve, if that's what you choose to do. It gives 'body' to the harness, resists most fouling and heat, and allows you to lay it into corners and around obstructions as you like."

What I'm hoping to do is to have a lively discussion about how best to make or repair a harness. For instance, I'm going to be completely re-doing a '96 wiring harness to use on Big Blue, and I'd like to do it well. But all I've ever done is to put it in place, zip tie it in a few places, and then cover it with convolute.

Perhaps y'all could educate me on the better ways to do that?

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Gary, I can post some of what I've done both on Darth and the konvertible. One of the interesting things on Darth, the front harness I started with came from a 1996 Diesel F350 crew cab.

One of the items I have learned is the vinyl tape is ok and can be used most anywhere, but it has a tendency to come loose at the end you finish the run at. I have started using old fashioned friction tape on the ends.

Zip ties are your friend when doing major rewiring, they allow you to keep the "can of worms" under control, and different colored ones can be used to denote take outs, inputs and corner locations.

One item, Ford, after 1985 used a pretty standard color and circuit numbering system. Pre-1986 dots and dashes were used for the secondary color, 1986 on it became a stripe. You will find that if a 1985 truck used a specific color and circuit number, a 1996 will have the same color and number. I first discovered this building a 1958 Country Squire and adding a number of newer items to it, particularly on the lighting, the same colors for running lights, stop and turn, headlights were the same colors. The other item is harness numbers, Ford is pretty consistent on using the same harness numbers as far as the center number.

Examples: 14401 is the dash harness, on the Bullnose it may also be the entire front harness, 12A581 is the underhood harness, 9D930 is the engine harness, 14405 is the rear harness (down the frame).

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Gary, I can post some of what I've done both on Darth and the konvertible. One of the interesting things on Darth, the front harness I started with came from a 1996 Diesel F350 crew cab.

One of the items I have learned is the vinyl tape is ok and can be used most anywhere, but it has a tendency to come loose at the end you finish the run at. I have started using old fashioned friction tape on the ends.

Zip ties are your friend when doing major rewiring, they allow you to keep the "can of worms" under control, and different colored ones can be used to denote take outs, inputs and corner locations.

One item, Ford, after 1985 used a pretty standard color and circuit numbering system. Pre-1986 dots and dashes were used for the secondary color, 1986 on it became a stripe. You will find that if a 1985 truck used a specific color and circuit number, a 1996 will have the same color and number. I first discovered this building a 1958 Country Squire and adding a number of newer items to it, particularly on the lighting, the same colors for running lights, stop and turn, headlights were the same colors. The other item is harness numbers, Ford is pretty consistent on using the same harness numbers as far as the center number.

Examples: 14401 is the dash harness, on the Bullnose it may also be the entire front harness, 12A581 is the underhood harness, 9D930 is the engine harness, 14405 is the rear harness (down the frame).

Bill - Please do post how you've done it. And pics. That will help.

As for zip ties, I once bought a bag of ties that included red, green, yellow, and blue ones. I don't use those colors anywhere they can be seen, but I do like to use them as I mock up harnesses. Yours was a good reminder.

And you are right about the pre-86 wire colors. Your 1986 EVTM explains that the dots and hash marks were replaced by stripes. I also knew that the wire colors stayed the same for the same circuit over the years. But I didn't know the harness numbering was consistent. Good to know.

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Bill - Please do post how you've done it. And pics. That will help.

As for zip ties, I once bought a bag of ties that included red, green, yellow, and blue ones. I don't use those colors anywhere they can be seen, but I do like to use them as I mock up harnesses. Yours was a good reminder.

And you are right about the pre-86 wire colors. Your 1986 EVTM explains that the dots and hash marks were replaced by stripes. I also knew that the wire colors stayed the same for the same circuit over the years. But I didn't know the harness numbering was consistent. Good to know.

When I was doing the custom gauges and dash wiring on my Javelin I did use the Velcro server wraps.

I would use them over the colored wire ties because every time you need to lay a new wire or reroute it you need to cut the wire tie. With the Velcro you can just undo it move the wire(s) and make it tight again.

I then used the spiral type wire loom to hold it together when I removed the Velcro.

When you get to a place wires go in a different direction you can just "spiral" around it.

I also use the spiral on the fog / driving lights under the hood of my flare side, I can take a picture.

Split loom has it's place like maybe under hood or down the frame rail to the rear lights.

As for electrical tape youcan use it to hold the harness together in place of Velcro or wire ties but is not great for wrapping the full harness. When it gets hot the sticky un-stickies.

There is a pressure type tape made just for this wiring harness, I will see if I can find it.

Dave ----

 

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When I was doing the custom gauges and dash wiring on my Javelin I did use the Velcro server wraps.

I would use them over the colored wire ties because every time you need to lay a new wire or reroute it you need to cut the wire tie. With the Velcro you can just undo it move the wire(s) and make it tight again.

I then used the spiral type wire loom to hold it together when I removed the Velcro.

When you get to a place wires go in a different direction you can just "spiral" around it.

I also use the spiral on the fog / driving lights under the hood of my flare side, I can take a picture.

Split loom has it's place like maybe under hood or down the frame rail to the rear lights.

As for electrical tape youcan use it to hold the harness together in place of Velcro or wire ties but is not great for wrapping the full harness. When it gets hot the sticky un-stickies.

There is a pressure type tape made just for this wiring harness, I will see if I can find it.

Dave ----

Dave, in my statement Gary quoted (above) is a link to underhood harness tape.

Tesa also makes a harness tape for interiors, but its surface is more like moleskin, and the adhesive isn't as heat resistant.

I agree 100% that spiral loom makes branch circuits easier to deal with.

It not only allows you to see the wires in the harness, it expands so you can fish additional wires into the bundle with a cable snake (I don't know what you call these stiff piece of coated aircraft cable with a bullet end)

Race vehicles used to have really rudimentary wiring.

Today's canbus systems will throw a fault or not operate simply because a wire is too long, or short, or the contacts are a little dirty and the resistance is outside given values.

 

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(I don't know what you call these stiff piece of coated aircraft cable with a bullet end).

0

Fish tape? If I am understanding what you are saying.

I agree with the above about tesa tape. We wrap harnesses at 50% overlap. I prefer the braided loom to split loom for a couple reasons. Split loom has to be sized perfectly. Braided loom does not you can shrink it down as necessary. Braided loom is also easier to make break outs with, more flexible, and won't start cracking on you down the road the way the solid split loom will.

For setting up wire runs I prefer what we call temp ties. Panduit and other companies make them. They are a zip tie with a little tab that releases the lock so you can reuse them.

For final wire bundling I prefer waxed string tie or "cobra" head zip ties that are installed with a panduit gun like the GTS-E.

I avoid vinyl electrical tape at all costs most anything you need electrical tape for you can use silicone tape. It vulcanizes to itself permanently there is no adhesive. You can use this to make strain reliefs, terminate sleeving, water protection, dust protection etc. It can also be used to wrap wire bundles in areas prone to chaffing, debris, heat etc (like tesa tape) but will stiffen the bundle a bit.

Then I think everyone should have a good electrical contact cleaner and dielectric grease which can be used in pretty much all connections. I use a different brand for coax called STUF.

 

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I agree with the above about tesa tape. We wrap harnesses at 50% overlap. I prefer the braided loom to split loom for a couple reasons. Split loom has to be sized perfectly. Braided loom does not you can shrink it down as necessary. Braided loom is also easier to make break outs with, more flexible, and won't start cracking on you down the road the way the solid split loom will.

For setting up wire runs I prefer what we call temp ties. Panduit and other companies make them. They are a zip tie with a little tab that releases the lock so you can reuse them.

For final wire bundling I prefer waxed string tie or "cobra" head zip ties that are installed with a panduit gun like the GTS-E.

I avoid vinyl electrical tape at all costs most anything you need electrical tape for you can use silicone tape. It vulcanizes to itself permanently there is no adhesive. You can use this to make strain reliefs, terminate sleeving, water protection, dust protection etc. It can also be used to wrap wire bundles in areas prone to chaffing, debris, heat etc (like tesa tape) but will stiffen the bundle a bit.

Ok, I'm trying to get down to specifics. I've found several braided looms:

  • PET: This is good to 257 F.

  • Nylon: I can't find a temp rating on this.

As for the cobra headed zip ties, are these they? If so, I haven't found the gun yet. Any suggestions?

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I agree with the above about tesa tape. We wrap harnesses at 50% overlap. I prefer the braided loom to split loom for a couple reasons. Split loom has to be sized perfectly. Braided loom does not you can shrink it down as necessary. Braided loom is also easier to make break outs with, more flexible, and won't start cracking on you down the road the way the solid split loom will.

For setting up wire runs I prefer what we call temp ties. Panduit and other companies make them. They are a zip tie with a little tab that releases the lock so you can reuse them.

For final wire bundling I prefer waxed string tie or "cobra" head zip ties that are installed with a panduit gun like the GTS-E.

I avoid vinyl electrical tape at all costs most anything you need electrical tape for you can use silicone tape. It vulcanizes to itself permanently there is no adhesive. You can use this to make strain reliefs, terminate sleeving, water protection, dust protection etc. It can also be used to wrap wire bundles in areas prone to chaffing, debris, heat etc (like tesa tape) but will stiffen the bundle a bit.

Ok, I'm trying to get down to specifics. I've found several braided looms:

  • PET: This is good to 257 F.

  • Nylon: I can't find a temp rating on this.

As for the cobra headed zip ties, are these they? If so, I haven't found the gun yet. Any suggestions?

Cobra ties are one brand of low profile zip tie I have seen used.

The way the head on normal zip ties sits is bulkier, it can lead to chaffing issues, the "teeth" area along the flat part is also against the wire, and a lot of times you get that sharp tail.

Panduit's version looks like this and when cut the tail is not exposed. Also the smooth side of the tie rests on the wire... no chaffing.

panduit.png.d4bae31daea87cdbbc8115668ab9a1a1.png

If you look up zip tie gun you can find some cheaper options in the $20-$75 that work with all kinds of zip ties. A panduit GTS zip tie gun probably runs about $150.

Most of these zip ties both panduit and the reusable one (tab release) can be found at Grainger.

https://www.grainger.com/category/electrical/electrical-supplies/wire-management-cable-organization/cable-ties

They make quick work of a harness but speed comes at a cost. I am lucky I can buy bulk left overs here from Boeing auctions for pennies. But, I'm more old school and prefer to use waxed string tie AKA lacing tape, AKA lacing cord. It's cheaper and I enjoy it. The flat kind is what you want. You can find this unwaxed a lot of times with leather stuff. You can also get high temp stuff that has nomex in it which is usually black or white with black dashes down the middle. The preferred method is to do a clove hitch around the bundle then secure that hitch with a square knot.

This is an example:

https://www.amazon.com/Lacing-Cord-Nylon-Black-Width/dp/B00UYD9E6O/ref=sr_1_4?keywords=Flat+waxed+lacing+cord&qid=1580765902&s=electronics&sr=1-4

On the braided loom I have been using PET it has an operating temp of 257 degrees but a melt temp of about 450 degrees.

Nylon usually runs -50ish to 300 F whether it is flat or round braid, expandable or not.

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I agree with the above about tesa tape. We wrap harnesses at 50% overlap. I prefer the braided loom to split loom for a couple reasons. Split loom has to be sized perfectly. Braided loom does not you can shrink it down as necessary. Braided loom is also easier to make break outs with, more flexible, and won't start cracking on you down the road the way the solid split loom will.

For setting up wire runs I prefer what we call temp ties. Panduit and other companies make them. They are a zip tie with a little tab that releases the lock so you can reuse them.

For final wire bundling I prefer waxed string tie or "cobra" head zip ties that are installed with a panduit gun like the GTS-E.

I avoid vinyl electrical tape at all costs most anything you need electrical tape for you can use silicone tape. It vulcanizes to itself permanently there is no adhesive. You can use this to make strain reliefs, terminate sleeving, water protection, dust protection etc. It can also be used to wrap wire bundles in areas prone to chaffing, debris, heat etc (like tesa tape) but will stiffen the bundle a bit.

Ok, I'm trying to get down to specifics. I've found several braided looms:

  • PET: This is good to 257 F.

  • Nylon: I can't find a temp rating on this.

As for the cobra headed zip ties, are these they? If so, I haven't found the gun yet. Any suggestions?

Cobra ties are one brand of low profile zip tie I have seen used.

The way the head on normal zip ties sits is bulkier, it can lead to chaffing issues, the "teeth" area along the flat part is also against the wire, and a lot of times you get that sharp tail.

Panduit's version looks like this and when cut the tail is not exposed. Also the smooth side of the tie rests on the wire... no chaffing.

If you look up zip tie gun you can find some cheaper options in the $20-$75 that work with all kinds of zip ties. A panduit GTS zip tie gun probably runs about $150.

Most of these zip ties both panduit and the reusable one (tab release) can be found at Grainger.

https://www.grainger.com/category/electrical/electrical-supplies/wire-management-cable-organization/cable-ties

They make quick work of a harness but speed comes at a cost. I am lucky I can buy bulk left overs here from Boeing auctions for pennies. But, I'm more old school and prefer to use waxed string tie AKA lacing tape, AKA lacing cord. It's cheaper and I enjoy it. The flat kind is what you want. You can find this unwaxed a lot of times with leather stuff. You can also get high temp stuff that has nomex in it which is usually black or white with black dashes down the middle. The preferred method is to do a clove hitch around the bundle then secure that hitch with a square knot.

This is an example:

https://www.amazon.com/Lacing-Cord-Nylon-Black-Width/dp/B00UYD9E6O/ref=sr_1_4?keywords=Flat+waxed+lacing+cord&qid=1580765902&s=electronics&sr=1-4

On the braided loom I have been using PET it has an operating temp of 257 degrees but a melt temp of about 450 degrees.

Nylon usually runs -50ish to 300 F whether it is flat or round braid, expandable or not.

You sound like my dad, he taught me years ago how to lace up wire runs in an electronic chassis. He was an electrical engineer by education, but did an awful lot of his own work on things including building an air conditioning system for our 1948 Pontiac that was run by an aircraft hydraulic system so the compressor ran at a fixed speed. The plumbing in the trunk was so impressive, a fellow at a shop where the spare had been patched asked mom "what'ya got back there lady, a still?".

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You sound like my dad, he taught me years ago how to lace up wire runs in an electronic chassis. He was an electrical engineer by education, but did an awful lot of his own work on things including building an air conditioning system for our 1948 Pontiac that was run by an aircraft hydraulic system so the compressor ran at a fixed speed. The plumbing in the trunk was so impressive, a fellow at a shop where the spare had been patched asked mom "what'ya got back there lady, a still?".

So for re-wrapping the existing harness, do you guys wrap with Tesa and then the braided split loom or just the Tesa?

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