Solenoid question

S

storyteller

Member
I have a '37 and a question on the solenoid. As viewed from the engine side of the firewall, the RIGHT terminal has the hot battery cable as well as two wires going into the car. The small terminal on the front of the solenoid goes to the START switch on the dash. The LEFT terminal has a cable from the solenoid to the starter.
When wiring this I noticed a stamping of BAT near the LEFT terminal on the solenoid. It seems to me that the BAT stamping should be near the RIGHT terminal. Am I right or should the cables and wires be switched around?
 
Assuming you have the correct RBM solenoid, it should have the BAT stamp next to the right terminal. It will also have RBM stamped on the right mounting foot. However, it hasn't been unknown to find mis-stamped parts. Take a look at the upside down stamping of Bat-Field-Gen on page 4-23 of the '38-39 Ford Book. I also understand that old Henry himself stamped the 18-1 upside down on the first V8 to go into a production vehicle.

The correct '37 solenoid will be almost 3" tall, and have a brass threaded cap over the button on the bottom. Later RBM's eliminated the cap as of '38, and became shorter by about 1/4" in '40.
 
Thanks Alan, Apparently over the years the solenoid has been replaced and who knows, the one I have was probably made in Mexico or God knows where. My car is not bone stock and as long as the solenoid works OK, I can live with it. By the way, what does RBM stand for, I am relatively new at this.
 
Since it's essentially just a switch, does it really matter on which side the battery and starter are connected on a solenoid?
 
It depends on the way the solenoid is designed. If it is using one of the terminals as the power source it would . If not it should not matter which way it is wired, the solenoid coil pulls the connector into the contacts and will work in ether direction. Think these solenoid are wired to use one of the terminal as the connection to ground through the starter button to energize the solenoid. An easy test would be to do a continuity test between the side terminals and the center terminal. If one of them shows continuity, that is the battery side.
Edit: the diagram attached is for a (-) ground, but a (+) ground system would work the same way.
 

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JSeery said:
It depends on the way the solenoid is designed. If it is using one of the terminals as the power source it would . If not it should not matter which way it is wired, the solenoid coil pulls the connector into the contacts and will work in ether direction. Think these solenoid are wired to use one of the terminal as the connection to ground through the starter button to energize the solenoid. An easy test would be to do a continuity test between the side terminals and the center terminal. If one of them shows continuity, that is the battery side.
Edit: the diagram attached is for a (-) ground, but a (+) ground system would work the same way.
Click to expand...

So, if the solenoid is marked with a BAT terminal, it probably should be hooked up that way, but if the terminals are not marked, it can be hooked up either way.
 
storyteller said:
I have a '37 and a question on the solenoid. As viewed from the engine side of the firewall, the RIGHT terminal has the hot battery cable as well as two wires going into the car. The small terminal on the front of the solenoid goes to the START switch on the dash. The LEFT terminal has a cable from the solenoid to the starter.
When wiring this I noticed a stamping of BAT near the LEFT terminal on the solenoid. It seems to me that the BAT stamping should be near the RIGHT terminal. Am I right or should the cables and wires be switched around?
Click to expand...

If the Battery cable is put on the wrong terminal the solenoid will not engage Because there is no power to the pull in winding.
Bill
 
4dFord/SC said:
So, if the solenoid is marked with a BAT terminal, it probably should be hooked up that way, but if the terminals are not marked, it can be hooked up either way.
Click to expand...

Not sure it's that simple, I would think you would have to check them. The problem is the way the starter buttons works on the old Fords, it is just a ground path, so the power has to come from somewhere to activate the solenoid coil. These solenoids are designed to receive the power from the battery side terminal. If the power came from the button to the center connection then the other end of the coil could just be grounded through the solenoid case (some of the later (-) ground systems work this way) and the hookup of the side terminals wouldn't matter. If it is marked my guess would be it needs to be connected that way, if not, I would check it and see if it mattered. It is very easy to check with a meter or even a continuity test light. Same goes with the later two center terminal solenoids, if it is internally wired to connect the "I" terminal to the starter side terminal then it would have to be wired they way to work.
 
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