'55 272 w/ Overdrive

4

42 Flattman

New member
I have a question.....newly acquired '55 Customline w/272 - 3 spd w/ overdrive.....the wires on the overdrive unit have been cut (for whatever reason)....the T handle on the dash was pushed in and I assume it was in overdrive because it would freewheel......I pulled the handle out and I assume it is out of OD now since it does not freewheel now.....so is it ok to use it either way....as long as I only change it when completely stopped ?
(I plan to address the issue with the cut wires but that will probably be a few weeks or months down the road).....I guess I need some clarification on what the electrical part of the unit does and if just changing it in and out mechanically is a problem. Any input/education will be appreciated.
Thanks
 
The transmission will function as a 3-speed either way. The electrical part activates the overdrive. When in overdrive, the engine RPM is reduced. Obviously your transmission isn't going into overdrive if the wires going to it are cut. Pulling the handle out will give you engine braking when decelerating, saving your brakes somewhat. If you can get the overdrive functioning as intended you will be greatly rewarded for your efforts. It greatly improves the driving experience, especially on the open road.
 
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OK....so the only difference it makes currently is it will freewheel with the handle in and not freewheel when pulled out.....but nothing else changes......might as well run it "out" like a standard transmission until I get the cut wires issue handled.
Thank you.
(I have a '51 w/ working overdrive and yes, much better driving on the highway)
 

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Seems the handle function is backwards to me, but who knows. In any event when it is in freewheeling if you park the car that way it will roll off on you.

Is there a kickdown switch on the car? Possibly under the accelerator pedal, or on the accelerator linkage?

3-speed, as in a manual transmission, right?
 
Guys, I have a related question that could also have meaning to the OP. In the 50s there were both 6 Volt and 12 Volt cars with overdrive. Will the solenoid activate with either voltage, or is each unit voltage specific?
 
Gene F said:
Seems the handle function is backwards to me, but who knows. In any event when it is in freewheeling if you park the car that way it will roll off on you.
Click to expand...

From the factory, handle in was freewheeling to enable OD to engage.

Parking in reverse will disengage the free wheeling and prevent roll-off.
 
The solenoid and the operating relay are both voltage sensitive, so you should use the type that matches your vehicle’s electrical system. The kick down switch and the governor don’t care which voltage is used. Same thing with the reverse lockout switch if your transmission has one.

reman said:
Guys, I have a related question that could also have meaning to the OP. In the 50s there were both 6 Volt and 12 Volt cars with overdrive. Will the solenoid activate with either voltage, or is each unit voltage specific?
Click to expand...
 
42 Flattman said:
OK....so the only difference it makes currently is it will freewheel with the handle in and not freewheel when pulled out.....but nothing else changes......might as well run it "out" like a standard transmission until I get the cut wires issue handled.
Thank you.
(I have a '51 w/ working overdrive and yes, much better driving on the highway)
Click to expand...


I have a '55 with OD and confirm you understand it right. If my OD system is not functioning I prefer to pull the handle out as it helps with breaking in the hilly countryside.


When you get around to researching the cut wires, there's probably a reason they were cut, so you'll have to trouble shoot around. My recommendation is to test each component separately at the start, and then make a plan to get them sorted. I had a similar issue with mine, and it took several re-iterations to get it right. In fact in my case I would fix one faulty part, and then the next component in the chain would fail. Mine is still a 6 Volt, and ultimately the biggest issues were that the relay to kick the OD in along with the solenoid, weren't getting enough amps to engage. Overall many of the components were tired, so part of the solution was to hide a modern relay inside the case of the original one, build a new wire harness for the OD components, and eventually I had to rewind the solenoid. But when it works it is well worth the effort.
 
These transmissions have to lock out of freewheeling for reverse. The internal reverse shift linkage pushes the shift rail back but only for reverse. The cable pull locks it out fully when the cable is pulled out for manual shifting with no freewheeling action. Push the cable in for freewheeling and overdrive function. The solenoid pushes the overdrive pawl into the balk ring to lock in the planetary for overdrive when a person lets off the throttle as long as the governor is above on speed. Pushing the kick down switch with full throttle cuts off the solenoid and drops the planetary out of overdrive. It also momentarily cuts the ignition coil to allow drop out.
 
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