Here's my meager contribution to tech week, my first tech post. First a little history on my overdrive in my '50 Plymouth with the flathead six and three on the tree. I have a factory Borg Warner overdrive from a '55 Dodge in the car, it's a direct swap for the '50 three speed, no other alterations necessary and it gives a 33% gear reduction. Since I'm running an aftermarket head and intake with different throttle linkage, I didn't want to mount the factory type kickdown switch to the throttle linkage as was done from the factory. Here's how the factory did it. The factory kickdown switch is a two circuit switch, the first circuit interupts power to the solenoid, and the second interupts power to the ignition to release the torque from the solenoid pawl so that the solenoid will release. Here's the factory switch, it's big and ugly... The switch was mounted from the factory to the throttle linkage so that it would operate when the throttle was pushed to wide open. This allowed a full throttle kickdown much like a modern automatic. I had the factory two circuit switch, so I wired it according to the factory setup, and mounted it under the edge of the dash. Here's where I put it. To shift out of overdrive, I reach down and press the button. The first thing I found was that since I'm using a mini GM HEI distributor wired through a fuse block, when the kick down interupted the ignition circuit, it would blow the fuse to the coil and I'd be dead in the water. I decided that I didn't really care about full throttle kickdowns, so I removed the ignition circuit from the switch. This meant that in order to kickdown the overdrive, I have to release the throttle instead of full throttle, because the overdrive solenoid will not release if there is torque on the tranny from the engine. No big deal really. After driving the car this way for a while, I decided I really liked the kickdown seperate from the throttle, since it gives the driver more control and you can kickdown without accelerating, which comes in handy at times. The thing I didn't like about the setup was reaching down to the edge of the dash every time I wanted to press the button, and since the button was meant to be pressed by the throttle linkage, it wasn't easy on the finger to push it in. This is where the TECH part of the post comes in. I'd seen an e-bay auction some time ago for a vintage shift knob that had a button in the end of it, which I thought would be a great place to put the overdrive kickdown on my car. So I went to my local radio shack and looked through the buttons they had, and found a tiny little momentary switch that fits inside the threaded hole of the plastic shifter knob. The switch came in a package of two, one red and one black. I drilled a hole in the end of the knob for the switch, soldered wires to the terminals on the switch and covered them with shrink tube, and put it back together. Here's a shot of the knob with the switch inside it. The shift lever on the car is hollow, so the wires from the switch run through the lever to the column, and then down around the bottom to the join with the turn signal wires that run up under the dash. Finished install. I didn't occur to me that the circuit of the factory switch was normally closed, and the new switch is normally open. So, when I wired the switch into the same wires that were on the factory switch, I didn't have overdrive unless I held the button down. DOH! To solve the problem, I went back to radio shack and bought a 12v relay. I had no idea how to wire a relay, so I got out a tester and messed with it till I figured out how it worked. It helped that the relay has a clear case, so I could see what was going on in there. Once I figured out the relay, I wired it into the system, and now when I press the button on the shifter, it sends 12v power to the relay, which then opens the circuit in the overdrive solenoid. Now I can kickdown the overdrive without reaching down to the bottom of the dash. And a real bonus to having the switch on the shifter is that I can "click-shift" the tranny up through the gears, for five forward gears. Third gear on these trannys is fairly tall, so shifting from second over to third over is a big jump. Being able to use third direct from second over fills the gap. I start out in first direct, and shift manually into second direct. Once the car reaches 25 mph, the overdrive relay kicks in, and I let off the throttle to shift into second over. Then, accelerating up to the next gear, I manually shift into third while pressing the button on the shifter, which puts the car into third direct. Accelerate again and then release the throttle and the tranny shifts into third over. With the overdrive, the car will cruise easily down the highway at 70mph, and gets 19mpg to boot. Thats it... Pete
that is a great solution. thank you for taking the time to put that together. I use a borg warner od in my 57 ford pick up, and they are great. I'm sorry no one else even responded to your hard work. Keep it up this is a well done post and thank you for doing it.
Great post... I just picked up an OD tranny and will be using this as my set up..Man you saved my brain some thinkin.. EVILT
Hi Pete. I have been reading about everthing you have done to your 50 Plym on : www.50plymouth.com and you have really inspired me!! I got a 1950 Plymouth 4dr, flathead six, P20 - 3 speed manual. Was your overdrive a R 10? Do you know of one for sale? Mail: one.red@mail.com Yours Al Martin
That's pretty slick. Another option would have been put the switch under the gas pedal, so WOT would push the button. On the other hand, the seperate control is sure nice.
Al- Contact George Asche, his info is on my site in the supplier page. He rebuilds overdrives, and usually has a few on hand... Pete
That's how the factory did it, which makes the system work sorta like a modern automatic kickdown. I had planned to mount and wire the kickdown switch like this, but since I got rid of all the factory throttle linkage, mounting the factory switch as the factory did wasn't an option. I didn't want to put it under the pedal, where it might get wet, the factory switch isn't water proof. Also, for the WOT set up to work, you have to use the factory two circuit switch. One of the curcuits interupts the ignition to take the torque off of the solenoid pawl, letting it release. My HEI ignition didn't like this much, it blew the fuse every time I hit the switch. Now that I have the switch on the shift lever, I like it much better than the WOT setup. It gives me much more control being able to shift in and out of OD without using the throttle. Pete
That's good stuff. I'd been running a toggle switch under the dash of my '55 Chev. This'll give me something to think about for the future.
I realize this is an old thread, but can you put the pics back? Is this an auxiliary overdrive unit that is in addition to an existing transmission?
Amazing! I just found this very useful thread. Thanx, blueskies for this info. My plan is to convert the shifting-linkage to floor-shift since that was original in my '37. I'll try to find or make a hollow shift-stick, otherwise I'll solve the switch-issue in some other way. blueskies, how does the shift/OD-solution work today? Still OK?
I have been using this tip of the shifter switch idea with relay on my 40 Ford with 49 Mercury overdrive for two years now. Works well. The 40 shift lever does not have a hollow for the wires to pass through but a very small gauge dual wire was used and is seldom noticed by others.
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