Under Dash Resistor

Bob56

Bob56

Senior Member
Putting the original coil back on from one of those conversions. This is a picture of a car from this forum and also a diagram showing how to hook the wires up. They look totally opposite of each other. The picture shows the red wire going to the right side dash light wire to the left. The diagram shows the opposite. which is correct or does it make a difference
 

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I say it doesn't make any difference since the current passes through the resistor either way.
 
The resistor to coil terminal (resistor output) should only have the wire to the coil on it. The terminal that attaches to the switch should have the red wire from the switch and a wire to feed the instrument panel gauges. Feed for the gauge (or gauges) needs to be on the input side of the resistor so the ignition switch will turn on the instrument/s too. All the other circuits off the buss have their own switches.

Don't forget that a resistor is a load device. The gauges need full voltage to work properly.
 
The picture of the ballast is of a car that I took at last years meet so don't know if it is a repop
 
Bob56, Here is a diagram that I made for my 35. Notice the main power wire (yellow) going thru the ammeter to the resistor/fuse block. This is the way Henry wired it,
 

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That's about the only way it can be wired if you want the ammeter to function, but the question was related to the ballast resistor.
 
I mentioned the yellow wire going thru the ammeter to the terminal block since neither of his diagrams showed any power going to the assembly.
 
gearheadbill said:
Are all voltage resistors that are manufactured/sold for our cars equal? Better or worse performance/pricing?
Click to expand...

The only resistor to be guaranteed correct is an original ford unit. All others may have various specifications that are not necessarily correct. Their ohms rating cold (.5 ohms) might read the same on an ohm meter but if the resistor wire is different material then it may vary in ohms when it heats up and read differently to the ford one. Regards, Kevin.
 
koates said:
The only resistor to be guaranteed correct is an original ford unit. All others may have various specifications that are not necessarily correct. Their ohms rating cold (.5 ohms) might read the same on an ohm meter but if the resistor wire is different material then it may vary in ohms when it heats up and read differently to the ford one. Regards, Kevin.
Click to expand...

Thanks for this info!
 
Borrowed and temporarily installed a NOS resistor from a friend...says he thinks it's 46-8...but when I measure voltage both TO and then FROM said resistor I get the same 5.8 volts. What am I doing wrong? or is the resistor faulty?
 
gearheadbill said:
Borrowed and temporarily installed a NOS resistor from a friend...says he thinks it's 46-8...but when I measure voltage both TO and then FROM said resistor I get the same 5.8 volts. What am I doing wrong? or is the resistor faulty?
Click to expand...

If there is no current flowing through the resistor there is no IR drop and the voltage will read the same on both sides. With the points closed and current flowing through the resistor and coil, you should see about a 2 volt drop across the resistor.
 
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