Need wiring schematic for gyromatic-fluid drive

[Guest sinker1980]

I need to rewire my 52' Coronet from coil to transmission. Any help or a wire schematic would be very appreciated! I have been having troubles with no upshift, I have tested the kick down switch, governor, and finally the solenoid. The solenoid has constant power with the governor lead wire disconnected so I am assuming there is a short in one of the wires to the solenoid. The previous owner had rewired it at some point but I am unsure if they are in the correct positions. Thanks in advance for any help!

[Rusty_OToole]

I have the diagram in a book but don't know how to put it on the internet. If no one else chips in I may have to learn *shudder*. Let me know if you find it.

[Guest sinker1980]

Thank you, I found one last night in an older post. I have rewired it all this morning already and am coming up with the same results. I still have constant power to the solenoid. Thinking I need to go back to the governor again. I'm just wondering if I am on the wrong track, the transmission is attempting to shift but grinding as it does. Would this be more of a mechanical issue? Would it just not try to shift at all if the governor/solenoid weren't working properly? Just thinking out loud.

[Rusty_OToole]

The solenoid controls the hi-low shift. It should be energized when the transmission is in the low gear position (of either high or low range). Above 14 MPH (high range) power to the solenoid is cut off,by the switch in the carb when you lift off the gas, allowing the valve to close and shift into hi.

In third speed (or first speed) the whole circuit should be energized except for the interrupter switch. In fourth (or second) the whole circuit should be dead. When the kickdown switch in the carb is activated the whole works should be energized including the interrupter switch.

The interrupter shorts out the ignition for a split second to allow the gears to engage on the kickdown.

[Rusty_OToole]

It takes a while to figure out what is happening when the tranny shifts. Basically it is like a manual trans with a hydraulic cylinder controlling the 3-4 shift. There is a little gerotor pump on the back of the trans to furnish pressure, and a solenoid valve to control it. When the solenoid is energized it opens the valve allowing pressure to drain away. Cutting the power allows a spring to close the valve, and the pressure shifts the gears into high.

IMPORTANT I just noticed something in the book that I had forgotten. Your engine has to idle at 450 to 475 RPM for the transmission to shift properly.

This is very slow by today's standards, barely turning over. If someone has set the idle to today's normal it is way too fast. Adjusting the idle may solve your shifting problem.

[Guest sinker1980]

I have made sure that the idle is set, with a good tach it is running pretty steady at 460rpm. One question that I have is: does it need to be running in gear while I test the solenoid? I have tested it multiple times with just revving the engine to rpm speeds associated with the proper mph speeds that it takes to shift (14-16). I am also wondering if there is a way to check/clean the filter in the tranny without dropping the tranny? Or is there a way to check for the proper pressure for the shift to occur? Just thinking out loud again. Thanks again for the help!

[Rusty_OToole]

There isn't any filter to worry about. In the factory manual is a series of tests for the electrical controls, all done in the shop using a test light with the engine off but the key on. In all cases, checking that each part is getting power when the key is on.

The anti stall (on the carburetor) and the solenoid are tested by using a screwdriver or soft iron to check if they are magnetized when turned on.

The only tests done with the engine running are the governor, kickdown, interrupter and resistor tests. The governor is supposed to go off at 14 MPH.

Pressure in the trans should be 38-40 pounds but there is no way to measure this directly. It is necessary to remove the shifter fork lock screw and insert a pencil, then rev the engine up with the car in gear and jacked up on jack stands, and feel the shifter move when you let off the gas and shift.

[Guest sinker1980]

Well I think I am down to mechanical issues. I took the interupter switch out today to look at the shift rail (think thats what it is called) and it did move forward pretty freely. It would go so far every time then start ratcheting violently up and down, that would explain the grinding noise! I guess I will have to tear into it afterall, anyone know where to find parts for these if need be?

[Rusty_OToole]

It might be easier to put in a used transmission. There should be lots around, they usually don't wear out. An appeal on the Chrysler for sale board may turn one up.

M-6 transmissions are all the same 1949-54 Dodge, DeSoto or Chrysler, 6 or V8 or straight eight.

There were some changes made during this period such as a change from a plate type synchro to a pin type synchro and a change in the way the interrupter switch was actuated which called for moving the interrupter farther back on the transmission. The transmissions themselves interchange but if you want to rebuild yours you will need to be careful to get the right parts.

[c49er]

Be careful to visually checking on a used replacement M-6 transmission. 1949-early 50 have a brake band on the rear brake drum. Late 1950 on up to 53 have a brake drum with internal brake shoes. They will not easily interchange because of the E-brake cable is different. Watch out for differences of the rear brake drum U-joint yoke. Chrysler/DeSoto and Dodge all use different style U-joints, meaning a drum swap is necessary. Also the date and model of the car the trans is from is stamped on the case by the shift cover.

I have seen many of these M-5/M-6 transmissions that have worn out input shaft/ direct speed blocker ring and sleeve banging or popping out of high range. Used to repair a lot of them over the years.

Quick way to make sure it's not an electrical issue is to drive the car with NO wiring hooked up and if it upshifts fine then , you know the internals of the trans are ok. NOTE- it will not shift down till you come to a complete stop and wait a few seconds with the clutch held in.

Bob