This is how I completely repaired the tailgate window regulator, lift motor, panel, seals and window channel felts on my 1962 Mercury Comet station wagon. Note: This will also apply to Ford Falcon wagons, and would also be helpful info for other old Ford/Mercury station wagons like the Country Squire, Galaxy, Mercury Meteor, etc.
Most Comet and Falcon wagons came with window cranks on the exterior. But there must have been an option for a rear power window, and that is what my Comet has. Only it doesn't work and likely hasn't worked in decades.
Just getting it open was an ordeal. The way it works is the rear window rolls down (either via the switch in the dashboard or the key-operated switch on the exterior of the tailgate), which allows you to access the interior lever that opens it. If you try to open it from the inside and with the glass still up, it can't open because the glass goes into the window channels. And the window's motor and regulator was totally jammed up and not budging even slightly.
So I had to crawl inside, unscrew the window channels, and then carefully push it open with the glass still up. First time the tailgate had been opened in maybe 40 years! Then I could pull the glass out of the tailgate, unscrew the interior panel, and take out the window regulator and motor.
It turns out the motor has two field coils - one for up and one for down. Now-a-days the motor would just have two wires and you reverse the polarity to change the motors direction. So this means I couldn't use the switch(s) and wiring harness unless I wanted to buy a NOS motor which sells for around $300. No thanks! Plus, the key I have for the car doesn't fit the key switch on the tailgate for some reason.
So I decided to get a doorman window motor and rig it to the regulator (after cleaning it up) and redoing the switch and the circuitry. I found a good video that explains how it works with two-wire motors and I adapted it to this schematic:
The two relays allows me to keep the OEM switch on the dashboard, otherwise I would have to change it out for a momentary DPDT switch. It WOULD be possible to wire the keyed switch on the tailgate to this circuit. Just wire it exactly like the dashboard switch, and connect it to the black wires from the relays.
I placed the relays at the rear of the vehicle so that only four wires were needed to run the length of the car. This allowed me to re-use the original wiring harness for the optional rear power window. The yellow and green wires were repurposed as the two ground wires going to the switch, the larger red wire with the yellow stripe was used for the yellow wire in the above schematic, and the smaller red wire was used as the white (grey) wire in the above schematic.
And for the wires going to the motor itself, I reused the large black wire and the large red wire with yellow stripe. It didn't really matter which wire connected two the red and black wires coming from the new doorman window motor. Because one throw of the switch will send the motor spinning in one direction, and the other throw will send it spinning in the other direction. So if down was up, then all I would need to do is swap the two wires on the switch for each other.
I got started on wiring that last night, I just need to wire up the switch now, add the fuses and temporarily connect it to a lead acid car battery, and then connect it to the new window motor. Here's the new window motor graphed to the old window regulator, it of course didn't fit right away but I was able to... correct it, sir. (That last part was to be read that in the voice of Grady from The Shining).
BTW you can also see the old window motor in the photo above, as well as the OEM momentary toggle switch.
For those who are reading this because they too want to graft a new motor to their old regulator: I used a window regulator that Rock Auto said was for the tailgate window of a 1969 Ford Ranch Wagon, DORMAN 742251. But to make it fit, I had to flatten the plastic surface around the three mounting holes, and modify the regulator a bit where the motor bolts to it (i.e. drill new holes and cut off some of the metal). But after that work, the gears where not hardly touching/meshing at all because the gear from the new motor needed to be a bit taller. So what I did was I removed the C-clip and removed the gear from the new motor. Then I added a spacer, only 1 or 2 mm thick, onto the shaft that the gear slides on, then I put the gear back on. It now sticks out 1 or 2mm and can mesh with the regulator gears, but it still meshes with the gearing in the motor. So far it's working great!
Now I just need to finish up the last bit of wiring then I can test it out. But I won't be able to put the glass back in until I receive the new window channel felts in the mail, but that is OK because I also have a lot of rust I need to fix first too. I've been leaning pretty heavy on Por-15 for much of that kind of work, but gotta draw the line somewhere.
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I just finished the wiring at the regulator works perfectly! Took a little while to get it mounted back onto the tailgate because I had to get the two lift arms perfectly parallel, which is hard to do
Still a lot more work to do though. Patch the rust on the interior panel, repair the horizontal piece that holds the glass (it's broken and rusty), and add all new seals and window channel felts. Clean everything up and put the window back in and take it for a spin!