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Overdrive on D14?


Marcel Backs

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A friend of mine has access to an old mopar overdrive. Could you get an overdrive unit on a D14 back then? If so what type and model of OD unit would it be? If an overdrive is possible on this car, what is required to install one? Any guidance on this would be greatly appreciated. As if I don't have enough to do I'm just thinking this might be a good mod in order to spare the flatty at highway speeds while keeping everything looking stock. All the best to everyone! M

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Hello Greg g - I’ve actually been wondering the same thing for our 1948 dodge D25c  Cl coupe, Canadian build.  it has the three speed manual transmission that matches the R10 G-1 overdrive transmission we have , it has the cable shift which I think I can manage to hook up , it’s the electrical components that have me scratching my head..... I would really appreciate any direction you could give me  

Edited by Saskwatch
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My transmission is shifted via rods with ball links. BTW thanks for sorting this out for me. Any idea what a fair price is for one of these OD units? All the best from the great white north aka Quebexico (we just got a foot of snow here...yech!). M.

PS it is a Chrysler brand od but not sure of model number???

Edited by Marcel Backs
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There is the factory OD operators and maintenance guide in the resources section of this site.  If not there, it is in the dow!loads section.  There are three major electrical components for the r10.

 

RELAY, takes the signal from the run or add terminal of the ignition switch to switch the power side to power the

SOLENOID this provides two functions the pull in circuit about 12 amp load, and an internally switched hold in circuit 6 amps that engages through the movement of the pull in. These are controled by contact points internal to the solenoid.  Both of these circuits are grounded through the                     

GOVERNOR which allows the circuits to be enabled by the vehicle attaining cut velocity of 38 mph or so.  And disrupts the ground when speed falls to also 30 mph

There is also the

KICKDOWN SWITCH which shuts the OD out when wide open throttle is used for passing accelerating of climbing grades.

CONTROL CABLE which allows the operator to select OD or non OD operation for the current driving conditions.

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Thank you Greg for the explanation, it is starting to sink in now. 
   I read in one of your posts where you moved the kickdown  switch from the carburetor to inside the cab. 
 Since I don’t have this switch or the carburetor that houses it,  a driver operated switch from inside the cab sounds better to me. 
  So if I understand this correctly, once you have pulled the cable to engage the overdrive portion of the 3speed standard transmission, the solenoid & governor work together to automatically shift the overdrive into gear when the set speed is reached and out of gear when forward speed falls below the set speed? 
 This switch is for “turning off” the overdrive momentarily even if you haven’t dropped below the set cut out speed and once you are up the hill & back to cruising speed , you can flip the switch back on to re-engage the overdrive? 
  Really appreciate your patience ?

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Not quite. My switch functions to control the relay. In the factory state with the carb mounted kick down. The relay is always on with ignition on.  It operation is selected with the OD cable. The relay has two sides the low amp control side and the high amp power side, so my push pull switch turns on the switch side, then the cable selects whether the solenoid is powered through the governors ground.  The factory set up functions automatically when the cable is pushed in, as it is getting power with IGN on.

 

I think I put my schematic the download section.

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On further consideraion, yes, I can use the switch to drop out of OD similar to the kick down switch.  I have it mounted to the bracket for the signal light switch so it falls readily to hand.  I will say here that I usually engage the OD when in highway cruising mode. I am not into using split shift mode in urban or sub urban traffic.

 

There is one other operating situation that takes a bit of getting used to when the control cable is in th eengage position.  The OD freewhéels below 30 mph.  Meaning you loose compression braking under that speed.  If you have ever driven a two stroke SAAB, DKW, or Wartburg you know the feeling.

Edited by greg g
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I’m thinking that this is how I would like to have it set up also, if I can get it all figured out. 
  The “freewheeling “ sounds like something that I must be mindful of but here on the prairie , wouldn’t be all that often it would be happening & probably won’t be doing any split shifts either. 
  Just get up to cruising speed & slip it into 4th for a low rpm drive down the highway. ?

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On 1/17/2021 at 1:29 PM, Saskwatch said:

I’m thinking that this is how I would like to have it set up also, if I can get it all figured out. 
  The “freewheeling “ sounds like something that I must be mindful of but here on the prairie , wouldn’t be all that often it would be happening & probably won’t be doing any split shifts either. 
  Just get up to cruising speed & slip it into 4th for a low rpm drive down the highway. ?

I had a shop make several copies of the 1953 style kickdown switch mount. At least I think it was from a '53. I believe they'll work back to 1946 but I'm not certain. 

20210118_143638.jpg

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My car already has all the mechanical assemblies re installed and this might be a bigger job than intended. I can see where rearend ratio adjustments are more practical! But the OD has a certain cool factor to it. Thanks to all contributors to this thread for the interesting info. Makes me happy o have joined the forum! 

 

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