Ignition switch relay

[my4dv8]

We are doing a full rewire on a v8 , and want to use the original column drop ignition switch and know these can be a little temperamental , would it be necessary to fit a hidden relay to take the load off this switch? Thanks .

[Hyvolt]

I used the original switch in my column drop. I did open it up and clean it up. But, I use it now to turn on a relay that Powers up my "run" portion of my fuse panel. Off of that panel are all my individual circuits for my guages, coil, fuel pump etc

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[Charlie Stephens]

Originally Posted by my4dv8

We are doing a full rewire on a v8 , and want to use the original column drop ignition switch and know these can be a little temperamental , would it be necessary to fit a hidden relay to take the load off this switch? Thanks .

I have never heard these switches were temperamental. If you are keeping the original wiring circuit and just going to 12 volts there shouldn't be a problem as a 12 volt system uses less current. What year is your car?

Charlie Stephens

[rotorwrench]

The OEM column ignition switch only powered the gauges and coil so it didn't have much current flow through it. If a person is going to add more accessories to that circuit then a relay might be a good thought.

[russcc]

NOS and NORS parts for these simple switches are usually available from Fred SSO, Faribualt MN, Nelson Pease, Palmer MA or Ray Helgers, Little Compton RI, among others. You may be wise to avoid new imposter stuff.

[RalphM]

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Wired my 36 switch, using 47 wiring schematic to get rid of column bottom switch, in 12 volt with no issues.

[Ken/Alabama]

I have one on my 40 convertible. The flip switch on the column powers a relay that feeds a fuse panel for the ignition,fuel pump & all the accessories like radio and heater.

[quickchange34]

Yes , use a relay with the switch if you plan to rewire and add accessories .

[FireEngineMike]

Hyvolt, would you post a picture of your wiring panel.

[Don W/Norfolk]

I would suggest the relay be one of the "continuous use" variety such as those used in golf carts. Google continuous use high amp relay. http://www.texasindustrialelectric.com/relays.asp is a good source with lots to chose from. dw

[flatheadmurre]

That was some real big relays...A normal car relay with dual points usually take 30amp splitting up into a couple of relays and fuses may be a better option since you can get a replacement relay in your local NAPA store...just my thinking.

[40cpe]

Originally Posted by FireEngineMike

Hyvolt, would you post a picture of your wiring panel.

While Hyvolt is getting back to post, here is a picture of the one in my '38.

The section on the right is switched hot, while the left side is constant hot. The relay is mounted on the upper right, but is dark and hard to see. The panel is mounted high on the firewall under the dash and is hard to photograph. The relay and constant hot side is fed through the large yellow wires from the "BAT" post of the ignition switch. All I have connected to the constant hot is the interior light.

[Hyvolt]

This is a pic of my panel build before it was done. I can get you more picsand all the details if interested, but it's not the only way to do it. I used a panel from a 2000 Windstar. Contains 28 circuits and 6 relays. I work for the electric utility locally and live in a world of complicated wiring so it may not be everyone's cup of tea. Total size is less than 12 square, and I mounted it in the same location as the original.

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[Hyvolt]

To add from my last post, my original coloumn switch activates relays in the panel, which energize a bank of fuses in the box. From those fuses I run a wire to the terminal strip. The terminal strip is where I land the wire to what ever I want to power off of that fuse.

I also have a self canceling turn signal switch that is done and functional. Have not made diagram or wiring print that is legible for anyone else yet, otherwise I'd share it

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[JSeery]

A 6v relay for a VW is a good reference. I can post the information if anyone needs it. One thing to be aware of is some relays contain a diode. If they are used with a positive ground system you have to match current flow (polarity).

[tubman]

"HyVolt" - Very impressive. More than I would need, but excellent work.

[Hyvolt]

I tend to get a little OCD on the wiring sometimes. Another option that I use are "Blue Sea Systems" fuse panels. Marine grade and lots of options. Prices are good also. And relays that are reliable with good prices pictured below. It doesn't cost much more to buy TE or Bosch brands. Stay away from the cheap stuff.

I also use DigiKey to buy my electric parts. Great prices and massive selection

The large relay is good for 75 amps. Small for 20/30

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[Hyvolt]

75 amps relay better pic

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[tubman]

I'm a fan of "Digi-Key" as well. Being in north-central Minnesota in the summer, I get most of my components the next day, even with their "Economy Shipping".

[Flathead Fever]

This is what I use. Standard LR-32 relay. They are not cheap $30.00 to $40.00.

We had fleet vehicles that were melting the electrical plugs on the back of the factory headlight switches. Too much current was going through the switch because of all the additional lights the body builder installed. We modified the circuit so the current went through this relay instead of the switch. Its nice they have that built in fuse.

[rotorwrench]

If I ever get back on my AV8 project, I'm going to set it up like an aircraft electrical system. The column drop switch will power up the battery relay. I use a big continuous duty one for high amp capability. I'll use Klixon circuit breakers for all the individual circuits set in a master electrical distribution panel. I've got a lot of that stuff around from being in the aviation business so long. The wiring will all be generic aircraft wire with numbered shrink sleeves at each end of the wire. The only color used is white PTFE insulation and the wire is silver plated. I like a nice clean heavy duty set up.

The old cloth covered wire Ford used still gives me nightmares. After about 15 years from new you can't tell what color the wire is anyway.

[FireEngineMike]

Hyvolt, thanks for the pics and info. JSeery posted info on 6-volt relays awhile ago which I will use. I have a collection of info at home, but your pics help with the layout. I have a pair of taillights on each side of the panel and plan on relays for the lighting and momentary use electric fuel pump. Eventually I will rewire the front of the panel and will add relays for the headlights (on the radiator support) and siren (a much larger relay on the firewall). Expect more info/help requests. Thanks.

[my4dv8]

Just to confirm this relay wiring through the original toggle switch . On the relay terminal 87 goes to Battery + , terminal 86 from original toggle switch , terminal 30 to the solenoid, terminal 85 to earth.
We will run a push button start .

[supereal]

At our shop we use starter solenoids for relays. The are less expensive than regular relays
and will, contrary to some opinions, operate continuously. On my '47 I use them for headlights and the convertible top pump, and so far they have lasted for over twenty years. We get them from NAPA, and for 6 volts they usually have to be ordered.

[Hyvolt]

Relay layout.
If you can't see it in the picture, the 30 terminal is for source. Has to do with the arc breaking in the relay. Will work if reversed, but that's from Bosch.

You may not have a 87a, it would be a normal close contact. I also always use 85 as my ground source for coil

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[JSeery]

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With this arrangement the original ignition switch is used as a grounding switch. This is ok, but all of the other functions have to be removed from the ignition switch and relocated to the fuse panel.

[Tinker]

Pretty slick stuff. Guess I'm just a stock harness and 6v guy.


Always good to learn something.

[Hyvolt]

Originally Posted by JSeery

With this arrangement the original ignition switch is used as a grounding switch. This is ok, but all of the other functions have to be removed from the ignition switch and relocated to the fuse panel.

True. If you wanted to use it in conjunction with the original wiring, reverse the coil connections.
Depends on what your goal is.


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