Installing Kill Switch

Sep 15, 2018 5:15 PM - 508 Views Create A New Thread

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Blaine, WA

Which lead to install kill switch into?
I'm about to install a kill switch in my '37 as well as charging lugs. They will be mounted close to each other in the trunk. Most kill switches I've seen put the switch in the positive lead, but I'm wondering if the negative lead might be better? In an accident, if the back of the kill switch touches the body, when in the positive lead, it will short out the system, where if the switch is in the negative lead, nothing would hurt if it touches the body. I guess in the end the charging lugs could also be a problem if they were to touch the body, so maybe it doesn't make any real difference. I think the NHRA wants them in the positive lead, but I won't be racing it anywhere. So.........long story short, is there a good reason to choose one cable over the other? Thanks, Bill

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  • Bill33
    Sep 19, 2018 at 7:41 PM

  • Actually this is only the second car I've built from the ground up. The other one is my 600 hp '33 Ford coupe I built 20 years ago. It won its class in the Grand Nationals and the Portland Roadster show. I now have 99,000 kms on it (about 61,000 miles) I do all the work nights and weekends as I own and run a construction business during the days. I do all the chassis fabrication, running gear, prep, paint and polishing, wiring and all other work, with the exception of the sheet metal work and upholstery. I'd hate to count the hours in this car, but I enjoy the building as much as the driving.

  • jimmothershead
    Sep 19, 2018 at 9:33 AM

  • When wiring a rod, I use grocery store produce twisties initially. That way you can add or remove conductors. When done, tie wraps installed.

  • jimmothershead
    Sep 19, 2018 at 9:30 AM

  • Bill
    Sounds like you have built a few...great ideas.
    All good things take time, no rush with old car projects.
    Old faithful took 5 years while doing other projects. Now has 141,000 cruizin' miles.
    Enjoy, Jim
    410 535 1933

  • Bill33
    Sep 18, 2018 at 1:00 PM

  • Thanks for the advice Jim. I did use the 1/0 multi-strand cables and did run ground to the bellhousing. I'm using a manual keyed kill switch from American Autowire. The '37 is painted and polished now, just waiting for an opening in the upholstery shop. The interior is all leather, with Mercedes carpet. I had hoped to enter it into the Grand Nationals in January, but won't make it, so maybe next year.

  • jimmothershead
    Sep 18, 2018 at 9:56 AM

  • Hey, Bill
    Since 1957, I have wired about 200 street rods. I switch the positive battery terminal. Ron Francis, American Autowire, Haywire, Painless use the positive .
    With all the clicker wireless controls for the past 30 years....I use a self latching 150 amp solenoid. Same concept as modern cars when you park and walk away...CLICK = locked. When I walk away from my rods...CLICK = battery killed. Or if Rosina smells smoke like she did in 1958 when the battery cable was burning on the ram horns = CLICK dead battery, photo attached... I have supplier info.
    Also I use multi strand 1/0 cables. If battery is in trunk, be certain to run negative to the bell housing bolt closest to the starter, not the frame like the attached pic.....Steel is a resistor not a conductor.
    Jim, School of Hot Rod Hard Knocks since 1957
    410 474 2244 cell
    410 535 1933, 410 535 1932

  • tazhog54
    Sep 15, 2018 at 7:43 PM

  • Either one will work , as you would have the same problem if in a accident,if it touch some metal would be on . Have done them both ways .and do prefer the negative side .

  • Bill33
    Sep 15, 2018 at 5:21 PM

  • I don't see any options for editing the body of the initial post any more, plus my profile picture is gone now.

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