Column-mounted Overdrive Kickdown Switch

DocHornet

Ever since I acquired my '53 Nash-Healey Lemans coupe (they all came standard with Borg-Warner Overdrive units), I've been intrigued by that model's OD kickdown switch, which is mounted in the center of the steering wheel, where the horn button normally would be, instead of under the accelerator pedal. This arrangement makes so much more sense, and there are many times you'd like just a simple, quiet downshift without a balls-to-the-wall gas pedal stomp.

With that in mind, I decided to engineer such an auxiliary system for my '51 Hornet Club Coupe. I just completed the column switch portion, by milling the housing for a spring-loaded bat switch out of a solid block of alumium. The housing mounts right on the back of the existing turn signal switch housing, and on the gearshift lever side of the column.

I used my lath to slice a round hunk of alumium from a 2" diameter rod


Then on to the milling machine to mill out the 'innards' to accommodate the switch, and finally to shape the exterior of the housing:


The final step was fabricating a cover plate for the rear. Even though it's not really visible, I wanted to do it right!


After a session at the polishing wheel, it turned out looking pretty good:



Tomorrow I'll re-assemble the whole assembly and wire it up. The switch is a nice heavy duty momentary-on starter switch I got from a hotrod house. Of course, invoking the Overdrive 'kickdown' mechanism involves breaking the connection to ground for the OD Solenoid. Ideally the switch would be closed at rest, and open when actuated, but it naturally works backward from that. So, I'll run the Solenoid ground wire through the Normally Closed contacts on a standard 5 pin relay, provide ignition battery power to one of the trigger legs, and the ground leg will come from the momentary switch (to actuate the relay and OPEN the solenoid ground contact). In this way, I only need a single wire from this switch to the engine compartment (relay), the other side of the switch is just grounded right to the switch housing.

After I get it installed, I may decide to add an extension arm to the switch.. I do have a Hudson-like turn signal plastic bullet end, but I'm thinking that just the switch alone will be readily accessible without further adornment.

UPDATE.. September 2013
After driving for awhile with this new switch, I feel like the entire character of the overdrive unit has been (favorably) changed. I actually fabricated another housing similar to this one because on the first the bat switch pointed downward at too much of an angle. Now with version two the switch is pretty much on the same plane as the gear shift lever when in high gear. It's a simple matter of sliding my finger down the gear shift arm and flicking the switch to downshift.. no extension was necessary. Here's what the new housing looks like:



I do still have the original polished aluminum enclosure and cover as depicted below (you'd have to source your own switch). I'd be happy to pass it along to another Hudson owner gratis if anyone is interested. Mounting just requires removing the turnsignal housing (two big screws), detaching the turn switch from the housing, then drilling 2 small holes in the back side of the housing to mount the O/D switch with a couple of small #4 machine screws

Glowplug

Thanks for sharing.

[Deleted User]

Ken you are a sick little puppy.lol

lostmind

Nice set up. Somewhere in my parts stash I have some commercially made kick down switches
that mounted on the gear shift lever. It used a knurled knob. Bad part was the wire is exposed
good part is , it's convenient . I had a switch mounted under the ignition switch on my 49,
easy to reach. Best part is you can kick out the overdrive with out using full throttle.
Your set up is the best I've seen , nice piece of engineering.

Park_W

Or, you can attain the same objective by moving the kickdown switch over to where your left foot can easily press it.

PAULARGETYPE

I HAVE NEVER LIKED THE KICK DOWN WITH THE OVERDRIVE I GUESS IT'S FROM SEEING THE FRONT SHAFT TWISTED FROM USING IT RUSS PEIRCE'S WIFE PEEP TWISTED OFF A FEW A LONG TIME AGO I GUESS IT PUT A BAD TASTE IN MY MOUTH ABOUT USING IT I ALWAYS JUST INSTALL A OVERDRIVE POWER SWITCH AND JUST DIDN'T INSTALL ANY KICK DOWN

[Deleted User]

The user and all related content has been deleted.

[Deleted User]

I agree with Paul ,never liked the idea of full throttle then kill the ignition to shock it to shift.
I too have placed a extra dimmer switch on floor to operate overdrive. However my latest one is on the end of the turn signal lever.
Roger

J Spencer

GEE! and all I did was install a switch under the left side of the dash and wire it into the ground side of the governor to solonoid wire so I can 'downshift' with out having to floor it.

Park_W

Or you can just move the kickdown switch over to the left, where you can depress it with your left foot. Done this on several cars.

kamzack

Regardless, beautiful workmanship, I admire and respect those who can accomplish such unique pieces.
Kim

junkcarfann

All you need is a column mounted auxiliary horn button, wired to the ignition to shut off current to the coil for a split second. That way you do not need to have full throttle.

onerare39

Great idea, very nicely done!

John

DocHornet

With all due respect, shutting off current to the coil is NOT what causes the overdrive to kickdown. In fact, in the stock system, current to the coil is never interrupted.

What IS used up front in the stock system is a momentary grounding of the distributor, cutting engine torque to allow the overdrive to slip back into direct drive. As soon as the overdrive solenoid drops back, it breaks that distributor ground connection, restoring engine operation.

Even that circuit doesn't directly affect the actual solenoid (Kickdown) operation. Instead, the ground lead to the solenoid relay is interrupted to take power away from the solenoid.

And, a horn button would be a good idea except that these are always normally OPEN switches. What is needed is a normally CLOSED momentary switch (not so easy to source), since under normal operation, the ground circuit to the overdrive relay has to be completed. That's why I wired my switch through a standard 5 pin relay, using the normally CLOSED circuit for the ground path. Then when power is provided to the relay, that circuit OPENS, getting the desired result down below.

And, of course, my primary motivation in installing this was to be able to downshift into direct drive without a full throttle action.

RL Chilton

Phil, would you please do a full write up on this operation, in layman terms, for future use, please? It would be great to have pictures, diagrams, 8 x 10's, etc., maybe in a PDF format. I'm sure we could get Alex Burr to include it in the on-line Library.

This is the type of thing Ken Cates used to have on his Step-Down Restoration Webpage, but is no longer active. I'm sure others would like to reference it for their own use in years to come.

Great work, by the way!!

DocHornet

I'll put that on my bucket list Russell!
Phil

Uncle Josh

I have the KD switch near the clutch like Park. If you mount it in the right place, you can press it with your heel when you push the clutch, allowing split shifting, ie 6 speed operation. I don't do it much any more, but 2nd OD to standard 3rd is a nice close gear.

Out dragged a 51 Ford with the old 49 that way once. Got it into 1st od and when I went to 2nd std it was all over. The equipment and me both are too old for that now.

Lee ODell

DocHudson, I like the steering column mount you made. Very creative.

In High School I had a 40 Ply 2 dr sedan that was bored & stroked with overdrive. Often drove it in 1st, 1st od, 2nd, 2nd od, 3rd, 3rd od. Real top speed was 105 mph. After replacing 2nd od trans I tended to be a little less of a lead foot.

Lee O'Dell

DocHornet

At Russell's request, I've written up a few notes and annotated wiring schematic to install a remote kickdown switch at the location of your choice, either steering column mount, dash or under dash mount, or floor mount as discussed by others. Any momentary-on switch can work:

Richie

Great write up Phil, thanks. Richie.

ernie28

This evening I have just finished road testing the Pacemaker after fitting the two alternative relays and an under-dash push button switch (the lovely column set up is out of my abilities just now) and boy what a great enhancement. It works so smoothly and is just so much better at slower speeds. The relays on the firewall sit well with the other relays even though they are of modern design they are not "in your face" with same colour coordinated and tidy wiring.

This weekend will see another decent run in the country and I am sure I will not be disappointed especially on the hills - having to use full throttle to down shift did not sit well with me at all even though it is still there if needed.

I felt like this after taking Geoff Clark's suggestion and fitted shock absorbers to my '28 Essex and that improvement was equally as good for that car. I am over the moon!

Many thanks DocHornet for a superb enhancement idea.

DocHornet

Glad it works for you Ernie... I myself have been amazed just how frequently I use the column switch vs. full-court-press on the loud pedal. I rarely ever use the throttle kickdown anymore!

It has completely changed my appreciation and enjoyment of driving this old boat!

Phil