Overdrive kickdown switch

Tomlewis

I am still working on resurrecting the ‘47 pickup I restored over 20 years ago and have not driven much since that time.  The truck has overdrive and, when restored, the wiring harness from Rhode Island Wiring and the relay from Al Saffrahn were correct.  I noticed today, as I was under the truck, that there was no kickdown switch.  There is a simple jumper wire where the switch should be connecting the two switch wires.

As I understand it, the function of the kickdown switch is to provide an interruption in the ignition circuit so that the overdrive can disengage. This happens so quickly that it is not noticeable to the driver.  If I don’t run a kickdown switch does this mean that I just don’t have the option of straight drive until the car speed drops under the overdrive cut-out speed, but all the other benefits of overdrive still apply?  I could certainly live with that.

On the other hand, if I really need a kickdown switch for everything else to work properly, does anyone have switches available?

I have Randy Rundle’s book on overdrives and can’t find a reference to this issue

Thanks. Tom

Jon B

Check the shop manual under transmissions -- there very well may be a wiring diagram for the overdrive circuit.

If you have a simple pushbutton or toggle switch for the overdrive kickdown, that a previous owner has wired up, I don't think you need to worry about devising something to momentarily break the ignition circuit.  If you're in OD (4th gear), just let up on the gas, which takes the stress off the overdrive, then push the kickdown switch.  Then resume driving (now you'll be in third gear).

If you want to set up the system as original, check the wiring diagram for correct wiring, and you can buy a floor plunger switch from Jeepsterman (or something like that), drill a hole in the floor under the accelerator, and install the new switch.  You may need to purchase a Hudson accelerator pedal with a special "lump" on the underside, which is specially designed to contact the plunger switch.  (In my case I just drilled and tapped the accelerator pedal, and put in a small screw with some washers.  Then I adjusted the height of the screw so that it contacted the floor switch at just the right level.)

Uncle Josh

I always move the kickdown switch from under the gas pedal to over by the clutch, then I don't have to be under full power to kick it down.  Also, you can push the clutch with your foot and the KD switch with your heel and split-shift it, giving you a choice of 6 ratios, like 1st OD to std 2nd, a close ratio for out-dragging Ford V8s etc. or 2nd OD to standard 3rd.

BTW,

Switch Kickdown

NAPA

OD6284

or OD6287 W/9/16 Jam Nuts