Borg warner overdrive

[gmc4hire]

OK, I hope this is the correct way to ask a question. I have Tom Endys article "Borg Warner overdrive". In it he provides a wiring diagram for the Model A Ford. I cannot figure out how to wire the headlight relay. I know the #30 is power in from battery, but what is hooked up to #85,86,87? Thanks in advance for any help.

[Dick Steinkamp]

I'm not sure what you are trying to hook up (headlights, Overdrive, other?), but here is a generic relay wiring diagram...

[Tom Wesenberg]

Is this a special relay from a newer car, and are those the actual numbers found on the relay?

Anyway, 85 is the ground side of the relay coil (it pulls the contacts closed), and 86 is the power from a simple off/on switch to turn the relay on. When the relay is ON then power flows from 30 to 87, which feeds power to the solenoid on the overdrive.

Why not eliminate the relay and just use a 10 amp switch to send power to the overdrive solenoid?

[40 Deluxe]

Originally Posted by Tom Wesenberg

Is this a special relay from a newer car, and are those the actual numbers found on the relay?

Anyway, 85 is the ground side of the relay coil (it pulls the contacts closed), and 86 is the power from a simple off/on switch to turn the relay on. When the relay is ON then power flows from 30 to 87, which feeds power to the solenoid on the overdrive.

Why not eliminate the relay and just use a 10 amp switch to send power to the overdrive solenoid?

Eliminating the relay will also eliminate the full throttle kickdown function, will it not?

[Keith True]

On mine I wired it direct,no relay.I think that a relay is a good idea,in theory,but seeing how there is nothing else in the circuit the only weak point would be the switch.If you ran the power through your ignition switch I could see potential problems though.The kickdown contraption is not used when the BW is converted to use on an A.I liked the BW,but it was really too high geared for me.

[tbirdtbird]

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let us know how you make out

[CarlG]

Even on the '50s cars that came with these OD units, the "kickdown" routine could be simulated by switching off the ignition for half a second, thereby foregoing pushing the gas pedal to the floor. This was done quite freequently in my Dad's '52 & '56 Fords and my '53 Mercury.

[Keith True]

My Studebaker still has that maze of wires,switches,and relays for the kickdown.I never liked that setup that kills the power to the coil when you stomp down on the pedal to shift it down.I ran the one on my 55 Chevy for years with a switch mounted on the shift lever.On when I wanted it,and off when I didn't.I sold that car in 1976 and the guy that has it says it still works fine.

[gmc4hire]

Thanks to you all. I will try to apply this new wealth of knowledge A.S.A.P. FM

[Tom Wesenberg]

Originally Posted by Keith True

On mine I wired it direct,no relay.I think that a relay is a good idea,in theory,but seeing how there is nothing else in the circuit the only weak point would be the switch.If you ran the power through your ignition switch I could see potential problems though.The kickdown contraption is not used when the BW is converted to use on an A.I liked the BW,but it was really too high geared for me.

I also very rarely use the kickdown feature on my factory setup on my 1950 Studebaker. My gearing is fine, in fact a bit too low with the rear axle being 4.55 to 1. I think 4.11 would have been better, but then in 1950 people didn't drive as fast as they do today.

The B/W is 33%, so I can see where that could be too much for the Model A with 3.78 to 1.