starter solenoid
- Thread starter oldskool
- Start date
12volt ford
BOSSY
Senior Member
Just tell them you want a 12V solenoid for a 70's Mustang. The 12V solenoids have 4 terminals. Positive to battery Negative to starter small post near positive to your start switch and the extra post you can leave blank or run a wire from it to your coil positive side and this gives it a full 12V to help start. Ron B.
Flathead Fever
Well-known member
You probably want a '57 to '74 Ford solenoid. Standard part number is SS581 or the heavy duty version SS581X. I do not like the heavy duty one because it is made out of bright blue plastic and does look right on a vintage car. Any auto parts store will be able to crossover this number to their brand.
There is a couple things to consider which I learned from my 40s era '32 roadster project. The 1940s Fords with a 6V positive ground system had a push button starter switch with a single wire that controlled the solenoid. This will not work with a Ford 12V solenoid which requires a push button switch with two wires. One wire is the 12 volt power and the other one energizes the solenoid. You can buy aftermarket two-wire switches but they will not look like the original Ford one that says "start" on it. There are a couple ways of getting around this.
I have attached the different wiring configuration for most of the starter solenoids. Figure #1 (SS-581) is a typical Ford 12V solenoid with a grounded base. Figure #2 (SS-587) has an insulated base, it gets its ground from the one wire terminal when the starter button is pushed. This might be a better choice for an original one wire starter button. This solenoid does not have the additional wire to send 12V to bypass the ignition resistor when cranking.
On my '32 I mounted a SS581 solenoid to the wooden toe board. Jumped a wire from the battery terminal to the starter solenoid terminal so it is hot at all times. Since the base of the solenoid is mounted to wood it has no ground. I then ran a wire from one of the solenoid mounting bolts to an early Ford single wire switch. When I push the switch it grounds the base and the engine cranks and the coil momentarily receives 12 volts for easier starting.
Here is a picture of a SS581 style solenoid in my '66 Shelby so you can see which wires go where. Facing the solenoid, starting on the left, the first wire goes to the battery, the second wire is the 12v wire from the starter switch, the third wire is the optional 12v Ignition bypass wire to the coil, the fourth wire is the starter cable. I can't show you the one in '32 because the car is torn down for paint.
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Bruce Lancaster
Member Emeritus
NAPA book I have shows ST 56 as a direct 12V substitute that will work from original grounding butto with no fuss. It actually derives from a 12V early Ford one, the Bus solenoid.
If you go to a late type that requires a hot wire instead of grounding, I believe you can get the 2 pole switch used on post 1952 Ford pickups, NAPA STB 10. I have not used this setup myself but have been told that this fits the dash hole for normal early Ford switch
If you go to a late type that requires a hot wire instead of grounding, I believe you can get the 2 pole switch used on post 1952 Ford pickups, NAPA STB 10. I have not used this setup myself but have been told that this fits the dash hole for normal early Ford switch
Roger/Sacramento
Senior Member
I bought a four post 12V solenoid. Does it matter which big post goes to the battery and starter?
ford 12 volt.
Roger/Sacramento
Senior Member
I already have the left post mounted to the starter and the right post to the battery. What will happen if I try to start the motor?
sturgis 39
BANNED
I am no expert but I think the solenoid gets the power from an internal circuit. The solenoid is energized from the battery. If you have it hooked up backwards it will just not work.
Roger/Sacramento
Senior Member
A friend of mine has two cars with the same solenoid installed. One has the battery wire on the passenger side post...the other has the battery wire on the driver side post of the solenoid. They both work fine. Looks like I will be OK either way.
Check the soleniod wiring diagram if avaliable. Most 12v ones have power applyed to energize not a ground as the older Fords do, I used a 12v tractor style as it looked like the original but used a relay to apply power through the original wire from dash, The original starter button is used to ground the relay so it turns on sending power to the starter. Need a 5 terminal relay they usually have a diagram on the side of them. This is what i have done to my 48 Ford when changing to 12v. Laurie
Flat Ernie
Senior Member
Use your stock 6V starter relay. It will be fine. I like the button on the bottom to bump the engine from the engine compartment too.
If you switch to a 12V starter relay & wish to retain a push-button starter switch, you'll have to do one of three things (in rough order of complexity):
A) use a harder-to-find, slightly more expensive, isolated 12V starter relay that operates with the original push-button [Pro: no changes, Con: hard to find starter relay]
B) switch to a two-post push-button to send 12V to a common Ford 12V starter relay from just about any Ford product and available nearly everywhere [Pro: very easy to find starter relay available anywhere for a few bucks, Con: rewiring for 12V circuit from push-button]
C) use the original push-button switch to complete a ground to a 12V cube relay that completes a 12V circuit to the starter relay [Pro: very easy to find starter relay available anywhere, Con: more complex wiring just to use original push-button]
For the time, aggravation, and money, I much, much prefer to use the original 6V starter relay, all original wiring, don't change a thing, and run it on 12V. Starter relays are momentary-use items and don't suffer from overheating on 12V like continuous use items like an overdrive solenoid (for example). If you crank and crank and crank your car, it may stick, but so will a stock 12V one or 6V one - fix the problem with your car not starting, don't rewire your car!
oldskool
Well-known member
thanks flat earie,the 6v solinoid is workingg fine,the engine is in tune and starts right up,your right about excssive cranking cooking even 12 solenoids ,i carry a spare 6v unit with me just in case,i also like the button on the solinoid makes working alone on the engine easyer for sure..regards..al
Topsterguy
Senior Member
I'm in the same position here and used a Select starter solenoid with the terminals in the same positions. Facing the front of the solenoid I have the left big terminal going to the battery, the small "S" terminal going to the ignition switch, nothing on the "I" terminal, and the other big terminal going to the starter................and when I hit the key nothing happens. So what's wrong ??
Topsterguy
Senior Member
I thought about that but it's bolted to the frame so that should ground it?