66 / 67 Charger headlight motors - want to know how they work?

[Meep-Meep]

I got a chance to see how diabolically clever these motors are. Simply brilliant! It's hard to explain, but there are no gears. What happens is you have a serrated surface that looks like a fine tooth gear on the inside of the round housing and a plastic cup thing with the same serrated finish. The two serrated surfaces do mesh but do not transfer power in the way you would expect. It took me a minute until it finally hit me. The plastic cup, being smaller than the inside of the housing, sort of orbits around and as a result you get rotary motion with lots of torque provided by the plastic cup. The impressive part of this whole operation are the three smooth rollers driven by a smaller sun gear (shaft really) that is also smooth. These rollers actually deform the plastic cup to the point it makes contact with the housing in three places. Best I can describe is it resembles the function of a Spirograph toy. I am still not done fussing with these so I will try and get better pics and description as I learn more. But for now if you want to tear one apart go for it.

What prompted all this was I had an issue with the lights. Seems one of the motors (or something) was acting up and managed to drain the battery because the micro switch didn't tell the relay to stop. No damage done except maybe the thermal overload in the motor. I have a buddy that has some extras and will get it fixed up soon. For now I just removed the roll pin to allow the door to open by hand. This is my first 66/67 Charger so it's only right I get initiated!

 

[696pack]

Cool! I had no idea they worked like this either. I always thought they were really smooth for a gear unit and this explains why.

 

[Greg Ducato]

not what I expected

 

[dpstark2]

I've taken about 8 of these apart. The motors are pretty neat. There are a few points of failure- the most common simply being a corroded connector. They have a dedicated ground connector, but they also ground through the body. Cleaning connectors and tightening the ground post have fixed a number of problems. They also have an integrated circuit breaker- it can fail open. Without a doubt, though, the limit switches have been the cause of the most headaches.

Interesting point- the fields measure out at about 1.2 ohms. At 14V, that's over 150W each!

That type of drive also has an interesting feature. When the shaft binds (or the bucket hits it limit) they basically sieze up and stop exerting force. This also means a sticky shaft (another cause of problems) can stall the whole headlight until you give it a little push.

Since all the current for these motors passes through the firewall (TWICE) they can also really suffer from voltage drops. I rewired mine to use standard relays in the engine bay. I did without cutting anything except my old wiring harnesses. I reused all the lines already coming through the firewall. The hold open switch still works too. Here's a pic.

I can put up a schematic if anyone is interested. They work much better this way and relieve the bulkhead connector from sourcing 25A to open or close them....

 

[dpstark2]

Hi,

I had a request for more information on moving the headlight relays to the engine bay. I did not have time to draw up a "better" schematic, but here is a link to my existing one.

Legend:
1. H/L on: headlights on signal from headlight switch.
2. CL: close limit switch line.
3. MO: motor open field line
4. MC: motor close field line
5. CAB: top half, refers to parts inside the car.
6. The little light: "Lamps not locked" light
7. HOSW: "hold open switch"
8. FW: refers to the firewall bulkhead connector and firewall side of the engine bay/headlight wiring harness junction by the battery.
9. HL: refers to the headlight side of the engine bay/headlight wiring harness junction by the battery.

Here's how it works (DISCONNECT YOUR BATTERY BEFORE PROCEEDING. DO THIS AT YOUR OWN RISK IF YOU DO NOT UNDERSTAND ELECTRICAL SYSTEMS):

1. Leave the control relay in the car alone.
2. Add two jumpers in the car to bypass the open and close relays:

a. Close relay: red SOLENOID to black SOLENOID (there are two red lines! The heavy one with a white tracer feeds the motor close fields. You want the red one that comes from the control relay output!)
b. Open relay: jumper light green (headlights "on" signal from the headlight switch) to the violet (motor open fields) connector.
​

3. In 2a, this bypasses the close relay and sends the "close" signal from the control relay to the "hold open" switch. The signal from the hold open switch (black) goes through the firewall to the headlight harness connector I'll discuss in a minute. Beware of this jumper- if you do things wrong, it will place a dead short of 12V through the 30A breaker in the kickpanel out to the close limit switch. It is good to test this circuit without relays, then add them in the engine bay
4. In 2b, this bypasses the open relay and sends the "open" signal through the firewall on the "motor open" line that normally powers the motors. If you do this wrong, you will send power to a motor field on a line not designed to support that current!
5. You now have the following at the bulkhead connector:

a. A "close" signal on the CL line with the HOSW inline.
b. An "open" signal on the MO line.
c. The OL line remains in place.
d. The MC line is disconnected
​

6. I spliced all the relay stuff in between the engine bay/headlight harness connection using pigtails from my old harnesses. If you don't have those, you'll have to figure out what to do on your own from here. It looks like this:

==engine harness==factory connector=>|<=old headlight harness connector==relay and splice==old engine harness connector=>|<==headlight connector==

7. Using the two pigtails, be sure to connect together the park and turn signal lights. Also connect the high and low beams unless you are also adding relays to control those.
8. Add a 30A breaker or inline fuse from the battery. Connect it to the +12V side of both new open and close relays.
9. Connect the switched side of one relay to the MO line (violet) going to the headlight connector. Connect the other relay's swithc output to the MC line (red with tracer) going to the headlight connector
10. Connect the two OL lines (dark green) to the negative side of the solenoid in the open relay. This is necessary to get the "lamps not locked light" working.
11. Connect the MO line (violet) from the firewall to positive side of the open relay. This completes the "open" circuit.
12. Connect the CL line from the headlight side of the harness to the negative side of the close relay solenoid.
13. Conenct the CL line from the firewall to the positive side of the open relay solenoid.
14. Terminate the MC line (red w/tracer) coming from the firewall. It is not used. This completes the "close" circuit.

There you go. I've done my best to make this clear. It's best to test the wiring without relays (use a test light to see the open and close signals turn on and off). Make sure there are no dead shorts where there shouldn't be. Shoot, even jumper straight off the battery and open and close your headlights a bit to make sure you have the right lines for that. If you have your open and close signals working, leave them disconnected, connect the relays, and then jumper the battery to the positive solenoid side of either relay and make sure the relays do their job that way too. Incremental testing is key.

When you're done, you will have relieved your firewall of sourcing 25A (twice), and given your motors the best voltage possible. If you do this, it's also a good time to add relays for your high and low beams. Same principle applies- use the signals to activate relays, feed the relays straight off the battery, send the relay output to the lights in place of the original signals. Your firewall is now 10-20A lighter, again.

Questions are welcome.

 

[440roadrunner]

Interesting point- the fields measure out at about 1.2 ohms. At 14V, that's over 150W each....

You can't figure motor draw that way. Series wound field motors exhibit what is known as "back EMF." They draw maximum current at stall, but less and less as speed builds up.

 

[dpstark2]

True, but I did measure them running free on a bench at over 10A and 12V... Either way it seems like a lot of current and it works better for me having them right off the battery.

 

[A383Wing]

I built a relay set to go near the battery for up & down motor movement and low & high beam headlights...plugs into factory harness under the battery and takes power right off battery

Bryan

 

[Terry Kitzman]

I got a chance to see how diabolically clever these motors are. Simply brilliant! It's hard to explain, but there are no gears. What happens is you have a serrated surface that looks like a fine tooth gear on the inside of the round housing and a plastic cup thing with the same serrated finish. The two serrated surfaces do mesh but do not transfer power in the way you would expect. It took me a minute until it finally hit me. The plastic cup, being smaller than the inside of the housing, sort of orbits around and as a result you get rotary motion with lots of torque provided by the plastic cup. The impressive part of this whole operation are the three smooth rollers driven by a smaller sun gear (shaft really) that is also smooth. These rollers actually deform the plastic cup to the point it makes contact with the housing in three places. Best I can describe is it resembles the function of a Spirograph toy. I am still not done fussing with these so I will try and get better pics and description as I learn more. But for now if you want to tear one apart go for it.

What prompted all this was I had an issue with the lights. Seems one of the motors (or something) was acting up and managed to drain the battery because the micro switch didn't tell the relay to stop. No damage done except maybe the thermal overload in the motor. I have a buddy that has some extras and will get it fixed up soon. For now I just removed the roll pin to allow the door to open by hand. This is my first 66/67 Charger so it's only right I get initiated!

Thanks a lot, I just bought the charger and they don't work so I will take them apart and see if I can spot any problems.