An Overdrive Question for you Guys

[Hudsy Wudsy]

I think that I recall that a '39 overdrive is still a mechanical, nonelectric unit, like the prior ones, except that it comes on a side shift transmission. Am I right about that? Also, if that's the case, when did the electric overdrive become available?

 

 

[John Loney]

I have the original OD unit on my ‘39 Imperial and it has an electric solenoid as part of its workings. I also have a complete spare transmission with Overdrive out of a ‘39 New Yorker...

[Hudsy Wudsy]

37 minutes ago, John Loney said:

I have the original OD unit on my ‘39 Imperial and it has an electric solenoid as part of its workings. I also have a complete spare transmission with Overdrive out of a ‘39 New Yorker...

John, thank you so much for your quick response. So '39s do have the electric solenoid. Would any of you know off hand how far up they will interchange?

[Spinneyhill]

I only know about Studebaker overdrives. The 1939 was the first with the kickdown feature, which meant there was a solenoid on it. The governor came a year or two later. Most Stude Commanders and Presidents were column shift, so yes, a side shift gearbox. Mine is a top shift box with o/d, which was an option. The Stude gearbox was on its side too, to reduce the height, so when you really get down to it, the "side shift" is really on the "top". The top shift has a hole and riser in the "side" of the gearbox on top. I hope that doesn't confuse you too much!

 

Thus the complete '38 o/d gearbox is shorter than the '39 because of the 3/4" thick plate between the gearbox and O/D box in the '39, on which the solenoid is mounted. So to interchange, you would need a change of drive shaft, not to mention to add the kick down switch, relay and wiring loom.

 

I think I have read Chrysler were a year earlier with the solenoid, because they were driving the development with Warner.

 

The Hollander says the '38 Chrysler C18 and '39 C22 o/d boxes interchange (not 7 passenger). De Soto of the same years are included in that interchange. The '37 o/d box will also fit in '38 and '39, but it doesn't say the later boxes fit the '37. An Underdrive was used in '41-'42 then another '46-'51 (called Underdrive, Presto, Tip-Toe and Gyro). It seems 1940 was a one year gearbox. So, how accurate is The Hollander?

[Hudsy Wudsy]

Thank you, Spinney, for being so generous with your time and your knowledge. You are always a big asset to these forums!

James Sheehan

Minneapolis, Minnesota

Home of the Final Four!

[Spinneyhill]

Here you go. Lots of information:

http://p15-d24.com/blogs/entry/88-the-rough-field-spotters-guide-for-mopar-overdrives/

 

Looking at the pictures of the 1938 box recently overhauled, it appears to NOT have a solenoid. The blog linked here says the first "electric overdrive" was 1939. That is the same as Studebaker then.

[countrytravler]

39 is the 1st year for electrics.  38 is the last year for mechanical.

Edited April 15, 2019 by countrytravler (see edit history)

[Hudsy Wudsy]

On 4/14/2019 at 7:15 PM, countrytravler said:

39 is the 1st year for electrics.  38 is the last year for mechanical.

Thanks, Dave.

[FLYER15015]

On ‎4‎/‎14‎/‎2019 at 6:15 PM, countrytravler said:

39 is the 1st year for electrics.  38 is the last year for mechanical.

Oopps,  My 31 Imperial has a solenoid sticking out the drivers side of the O.D. unit with 2 wires attached.

But mine was messed with long before I got it.

Never had the guts to engage the thing, as she never leaves town.

Have no idea where the 2 wires go, but I don't see an indicator light on the dash.

 

Mike in Colorado

[Spinneyhill]

3 hours ago, FLYER15015 said:

Have no idea where the 2 wires go, but I don't see an indicator light on the dash.

There will be no indicator light I think.

 

Is there a switch somewhere amoung the accelerator operating levers? On the Studebaker, it is attached to the carb. and the operating lever touches it on full throttle. It is a single push switch, makes the circuit when pressed and releases it when released. There should also be a relay somewhere - the solenoid switching current is a bit much to pull through the ignition switch. In a retrofit such as yours, you could even have a little push switch inside; I mounted one under the dash until I arranged the right kick-down switch. The relay often has a fuse in it too.

 

I think I posted the wiring diagram for the '39 Studebaker o/d somewhere.... It is separate from the main car wiring loom.

 

Here they are. 1939.

and here is the MoToR's Manual about the Nash version.

  This should be enough to help you work out what you have. The Chrysler version will be similar.

Edited April 18, 2019 by Spinneyhill (see edit history)