Gyromatic transmission in a 12v car

[celticsam]

I am going to convert my 49 Coronet to 12V.  I have been scouring the net for information on how to handle the servo on the Gyromatic tranny, but have only come up with "it can be done" - which just encourages me to find a way.  Before I mess up the tranny (or force a larger project), does anyone know how this can be done?  Looking at the wiring diagram, if I use a 12V to 6V converter or ballast resister on the red wire off of the coil (and switch it to the + side), that will power the transmission circuit with 6V negative ground.  Will this work?  Has anyone done anything that has? 

 

Before all the 6V faithful chime in, due to my wife's asthma, AC is a necessity.  Not a luxury.  That makes 12V also a necessity.  That goes before all the "brighter lights" and "modern stereo" arguments.  Sure was easier on my old 49 SD 3 on the tree ....

Edited October 30 by celticsam

[Doug&Deb]

I’m not aware of anyone who has done this successfully sorry to say. If you figure it out please share how. This is a question that comes up frequently. The trans will up shift with no electrical with no problem. It’s the down shift part that requires the electrical part.

[celticsam]

OK.  I found this (link below) which suggests that this is a solution to making the gyromatic 12v compatible.  Anyone have any experience?  1949 -1953 Chrysler DeSoto M-6 transmission 12 to 6 volt solenoid reducer/relay -M612K2

[greg g]

Have you looked at this from the opposite end of the question, what 12 v do you need to run the ac?  Seems the compressor clutch, and the circulation fan are what needs 12v.  Put one of those red top fancy gel thingies in to power those.  Unless you are in the car for long trips, seems if put on a charger over hight you would have 3hrs of ac, or go to a 6v to 12v step up to power the ac.  This one is 1/10 the cost of what you posted puts out 10 amps.  Or use it to charge the ac battery with engine on.  Couple articles I looked at suggested 6 amp to engage clutch and ~4 amps to hold in. Those compact compressors on small cars and hybrids probably draw less.  So instead of converting the car, build a seperate power source for the ac. 

https://www.kaiserwillys.com/products/dc-6v-5-11v-to-12v-10a-step-up-converter-module-fits-41-71-jeep-willys-923133/?gad_source=1&gclid=EAIaIQobChMI0vfNqYHDiQMViUn_AR3hUxZ_EAQYBCABEgJ5EPD_BwE

Edited November 4 by greg g

[kencombs]

8 hours ago, greg g said:

Have you looked at this from the opposite end of the question, what 12 v do you need to run the ac?  Seems the compressor clutch, and the circulation fan are what needs 12v.  Put one of those red top fancy gel thingies in to power those.  Unless you are in the car for long trips, seems if put on a charger over hight you would have 3hrs of ac, or go to a 6v to 12v step up to power the ac.  This one is 1/10 the cost of what you posted puts out 10 amps.  Or use it to charge the ac battery with engine on.  Couple articles I looked at suggested 6 amp to engage clutch and ~4 amps to hold in. Those compact compressors on small cars and hybrids probably draw less.  So instead of converting the car, build a seperate power source for the ac. 

https://www.kaiserwillys.com/products/dc-6v-5-11v-to-12v-10a-step-up-converter-module-fits-41-71-jeep-willys-923133/?gad_source=1&gclid=EAIaIQobChMI0vfNqYHDiQMViUn_AR3hUxZ_EAQYBCABEgJ5EPD_BwE

 

I would consider the opposite but similar approach.   Since the trans should use very little current, a small 6v battery feeding only that circuit may be a possibility.     Sure wish we could buy the old batteries that had exposed cell to cell connectors.   Tapping 6 v from a 12 was easy then.

 

AC clutches use a fair amount of current  as does the blower motor, maybe 6-8 amps total.     a dedicated battery for only that may not last as long as needed.

[celticsam]

On 11/4/2024 at 10:47 AM, greg g said:

Have you looked at this from the opposite end of the question, what 12 v do you need to run the ac?  Seems the compressor clutch, and the circulation fan are what needs 12v.  Put one of those red top fancy gel thingies in to power those.  Unless you are in the car for long trips, seems if put on a charger over hight you would have 3hrs of ac, or go to a 6v to 12v step up to power the ac.  This one is 1/10 the cost of what you posted puts out 10 amps.  Or use it to charge the ac battery with engine on.  Couple articles I looked at suggested 6 amp to engage clutch and ~4 amps to hold in. Those compact compressors on small cars and hybrids probably draw less.  So instead of converting the car, build a seperate power source for the ac. 

https://www.kaiserwillys.com/products/dc-6v-5-11v-to-12v-10a-step-up-converter-module-fits-41-71-jeep-willys-923133/?gad_source=1&gclid=EAIaIQobChMI0vfNqYHDiQMViUn_AR3hUxZ_EAQYBCABEgJ5EPD_BwE

I'm building the car to (hopefully) participate in the Power Tour 2026.  I've participated before (before the specter of Covid) and HIGHLY recommend driving in at least part of one.  A very good time.  In any case, the tour pretty much requires 4 - 6 odd hours of driving on each leg of the tour.  I would only trust a battery for 3 or 4 hours without charging it, and the 6 volt system on a '49 Coronet isn't up to the load of stepping up to 12 volts and keeping up with charging a battery being drained by a stereo and an air conditioner (or even just the AC).  Its a great idea if you limit your cruises to local events, not so great if you are planning any distance driving....