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Technical And awaaay we go...(a wiring question)

Discussion in 'The Hokey Ass Message Board' started by '50_SEDAted, May 7, 2019.

  1. '50_SEDAted
    Joined: May 4, 2019
    Posts: 21


    Annoying newbie question #1:
    The wire looms on my '50 Merc have disintegrated, and
    are disintegrating rapidly, especially under the hood; I've got gingerly-spaced bare wires running all over the place. I'm thinking a 12-volt conversion is in order (at some point), but (most) everything is working is it is, and I'd like to just enjoy it for a bit before I start tearing things apart. However, she's not gonna be nearly so much fun as an arc furnace.

    The loom has come apart clear up to the wiring harness on many wires. I'm thinking the best course of action is to carefully trim back the harness tape to uncover "good" insulated wire and then overlap heat shrink over the frayed end of the loom coming out of the harness all the way to the connections. However, I'm a little skeered about jacking around with the harnesses for fear of the looms inside the harnesses coming apart from too much handling. Are the cloth looms that have been encased in the harnesses typically sound, or am I going to be chasing unraveling insulation all the way back to the fusebox?

  2. Scootin
    Joined: Mar 6, 2019
    Posts: 4


    On my 49 Plymouth I thought the same as you. “I’ll just replace everything that’s obviously frayed and leave the rest till it needs it”.

    It’s all frayed. Everything up to the fuse box. If it’s not frayed right now, the act of disturbing the harness itself will probably cause it to fray. The cloth loom on my car was practically completely gone. There was yards of bare wire inches away from other bare wire and metal.

    My advice is to just rip it all out and start from new. There’s not that many electrical components in these older cars. Just label every wire and try not to cut the harness when removing it if possible.
    olscrounger likes this.
  3. David Gersic
    Joined: Feb 15, 2015
    Posts: 1,819

    David Gersic
    from DeKalb, IL


    Start here.

    A friend rewired his Hudson one wire at a time. Took a while, looks original. I did my 37 by cutting it all out, and going with Painless. There are many vendors, and options, but you’re looking at trouble with old frayed and disintegrated insulation.

    Sent from my iPad using The H.A.M.B. mobile app
    Hot Rod Nut, pitman and olscrounger like this.
  4. Ancient Chinese Auto proverb " If it's shit on the outside, it'll be shit on the inside".
    Do a good rewire job, you won't regret it. I have seen some nice fires started inside frayed looms.
    olscrounger likes this.
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  5. Rewire the whole car. It's just a matter of time before it shorts out or starts a fire.
    Finnrodder and olscrounger like this.
  6. rustydusty
    Joined: Apr 19, 2010
    Posts: 891


    Replacing the wiring will probably be cheaper than having it towed from wherever it craps out!
    ffr1222k and olscrounger like this.
  7. 4 Words: Rhode Island Wiring Service

    Most likely they will have a brand new wiring harness for your Mercury with the original style cloth covered wire. Or you can piece it together and replace one strand at a time. I did my Dad's '49 Packard that way. Turned out quite nice and everything works properly now.
    bobss396 and Pist-n-Broke like this.
  8. I just went through this on my 48 Ford. I tried just shrink wrapping all the frayed areas. But the more I touched the wiring, the worse it got. The final straw was when I went to crank it up and the smoke escaped from the wires under the hood where I thought the best wires were. So....I ripped it all out and it was a fragile mess and I rewired the whole shebang and converted to 12 volts. Now she will crank even before a complete revolution of the engine and the instruments work (you will need to shunt them to 6volts). But the gas gauge is a little off.
    Rewiring isn't all that difficult if you get a ready made harness and just connect the wires where they go.
    My recommendation, bite the bullet, you will be happier, safer and better off in the long run.
  9. You'll be chasing bad insulation…

    The old cloth-covered wire is actually more than that. The cloth is for abrasion resistance, under that is rubber insulation. At this stage, both have 'aged out'; if left undisturbed and not exposed to degrading environmental conditions (particularly heat), it'll last a long time. But as you've discovered, once it's to a certain point there's no help for it; touching it is nearly the same as destroying it. The cotton cloth turns to dust, and the rubber now just breaks and falls off. Add in the fact that the OEMs weren't very good at fusing circuits until the advent of single-point fuse panels, and that can be a recipe for disaster.

    You need to re-wire, but if you feel lucky and want to 'patch' it up for short-term use, I'd suggest getting some oversize shrink tube and very carefully slipping it over bare spots. Don't bother shrinking it, it's strictly mechanical protection.
    Pist-n-Broke and olscrounger like this.
  10. pitman
    Joined: May 14, 2006
    Posts: 4,607

    from Hampsha

    One unplanned crossing, and you and car, are toast. Good to run new circuits, w/a sound jacket, and connections.
  11. evintho
    Joined: May 28, 2007
    Posts: 1,150


    I think you've found the answer.
    A complete rewire is in order!
  12. Stooge
    Joined: Sep 9, 2015
    Posts: 272


    Yup, they aren't nearly budget friendly as a universal harness,( realistically probably twice as much) but Rhode Island Wiring or YNZ wiring will make you reproduction wiring harnesses for basically anything, and will help alleviate the amount of downtime, troubleshooting, dicking around, etc time that you may have with trying to find the right "whatever" replacement connectors for that broke in that hard to reach place under the dash or wherever. Though if you have enough non-stock parts in the car, it might not make much sense to use a replacement stock harness and a 12v American autowire or Painless kit could be used, ( I tend to like the American autowire ones a little better)
  13. '50_SEDAted
    Joined: May 4, 2019
    Posts: 21


    Thanks for the input, Gents.
    I would very much like to go the Rhode Island Wiring Service route, but I'm kinda strapped-- kid in college, n' all.
    I'm assuming, that at $2k for every harness in the car, the RIWS kit must be heavy-gauge 6v wire (?). In any case, if I'm going to rewire the whole thing, I might as well do the 12-volt conversion.
    If she was a '50 coupe, I'd totally wait until I had the dough to do a period-correct 6V rewire, whether I decided to actually continue to run 6V or or not. Even so, it does pain me a little; my little Blackbird is very nearly bone stock, except for a 6V fuel pump and and a coolant overflow reservoir.
    This is the kind of thing that'll keep me awake second-guessing myself -- period-correct 6V rewire, or a 12V "Painless" kit with a modern blade fuse panel.
  14. Or you could save loot & learn a heap of skills and do the rewire, one at a time, yourself. There are lots of good books available. If you grab a complete loom from a large, late model car from the wreckers, you will have more than enough wire to do the job. I'm sure someone on here can suggest a suitable model. Some ring & spade terminals, fuse panel, a multimeter, and plan & record what you've done. These jinkers we play with don't have many circuits, treat each separately, and give it a go!
    pitman likes this.
  15. leon bee
    Joined: Mar 15, 2017
    Posts: 274

    leon bee
    from Arkansas!

    I'm also in the tear it all out and go back one wire at a time camp. You don't need that many new wires to get her on the road. Edit: that is if you don't have safety inspection where you live. Ignition, generator, brake lights, signals- hit the road.
  16. deucemac
    Joined: Aug 31, 2008
    Posts: 942


    If you don't rewire the car completely, carry a large fire extinguisher, and practice getting out of the car quickly and carefully!
  17. '50_SEDAted
    Joined: May 4, 2019
    Posts: 21


    Yeah, I think I might go the Johnny Cash piece at a time...
  18. ffr1222k
    Joined: Nov 5, 2009
    Posts: 1,022


    Rebel Wire makes a 6 volt harness and they are a vendor on the HAMB. If you are an Alliance member you also get a discount. The Universal 6 Volt Harness is $285.
  19. The Shift Wizard
    Joined: Jan 10, 2017
    Posts: 1,253

    The Shift Wizard

    The litmus test for me is "white knuckle syndrome". If I'm consciously or even unconsciously worried and sweating it every time I go for a drive, I'm not enjoying the experience. That's like having a relationship with a mean-talking, knife-toting woman. What's the point in that?

    To quote the old TV show.........
    "We can rebuild him. We have the technology. We can make him better than he was. Better, stronger, faster."
  20. 4wd1936
    Joined: Mar 16, 2009
    Posts: 739

    from NY

    A good fire extinguisher costs as much as a decent wiring harness, I think I would go with the harness. Seriously, it all depends on whether you want to stay original or not. Other than bulbs a six volt harness will handle a twelve volt setup if you want to change over later, much heavier gauge wire in a six volt to handle the amperage. The RI guys are great, been using them for years, and although they are a bit pricey you get a quality product. I have seen/used the Rebel six volt harness and it is a good alternative to original(RI) if price is the deciding factor. Either one install a good battery shut-off and use it, I think it prevents early gray hairs, boldness and underwear stains.
  21. Do it right, do it once.
    I did a COMPLETE rewire on my 51' Merc (Avatar) using a wiring "kit" don't remember the brand (Rebel, EZ, Painless) and it's really not that big of a deal. Down for a few days and lots of trouble free miles and piece of mind.
  22. "I'm a little skeered about jacking around with the harnesses for fear of the looms inside the harnesses coming apart from too much handling."

    I think this statement shows your common sense leaking out. You already know what might be going on where you can't see it. My experience, and I've had a bit with old cloth covered wire, is that it's a good bet if you dig deeper you will find something in way worse condition than you have already found. It would be a shame to loose your ride to a fire because you didn't heed the warning signs you've already seen.
    pitman and TrailerTrashToo like this.
  23. Replace it, the Rebel 9+3 is a good value and they are an alliance vendor here. Look at the Rebel thread on here. I put a Kwik Wire 14-circuit in my '59 Ford and it was a breeze. Take out the front seat to give yourself lots of room under the dash.

    I first figured where I wanted the fuse panel. Then measured up to see where I wanted to run the main bundle. Them measure the break-outs from a known point, I used the steering column. Then slapped the harness/fuse panel onto a piece of plywood, made a harness board, used finishing nails to route the wires. Tied with zip-ties and put it in the car.
  24. '50_SEDAted
    Joined: May 4, 2019
    Posts: 21


    Yeah, the Rebel Wire 6V kit is very reasonably priced, and I am familiar with their product as I installed one of their kits in a '65 beetle. Im'ma order it this week.
    Next up...water pump(s)...

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