Overdrive relay

JFromm

Are the overdrive relays the same from 1948 to 1954?

Park_W

No, they made a big change for 1950.  The OD relay became just a simple everyday relay, this made possible by a change in the kickdown switch.  The earlier switches have only 2 terminals, and they open a circuit to the relay, which then triggers the ignition shorting that allows the OD to kick down.  On the '50 and later cars the kickdown switch has four terminals and does two functions: It opens the control circuit for the relay, and at the same time it closes a circuit from the OD solenoid to the coil to take care of the ignition shorting function.  This was a big improvement, as it got rid of the overly complicated OD relay and replaced it with a simple one.  The OD wiring circuit on the later cars is somewhat simpler because of the change in the relay.

JFromm

Thanks. Park