Automatic Overdrive Unit.

[RICKYMOPAR]

I just was checking if there were any good used automatic overdrive units for sale? I have thrown these away and now find I may have tossed mine! I have found many junk non-useable units, that are not even repairable. If you need help with yours I have lots of resources for operation and maintenance, as well as wiring, relays etc. Let me know! Rickymopar

[rogerh]

I guess it is just the way I am interpreting your words. There is no such thing as Automatic Overdrive, is there? . Overdrive applies only to Manual Transmissions, and I think it has to be manually activated by pulling a dashmounted handle while in motion????.

[RICKYMOPAR]

Being in the trade for way to many years, I guess I should inform you that the overdrive units Chrysler used in their vehicles were indeed automatic and incorporated electronic controls in addition. By pulling the handle you disabled the automatic and locked out the o/d. A slider locked the ring gear to the output eliminating any possibility of an upshift, and opened the control circuitry for the activation of the automatic overdrive solenoid. When the handle was in'the normal position' the overdrive unit would automatically shift in at about 25 mph.
Second gear and overdrive could be alot of fun, being that when you would floor the accelerator pedal the unit would shift out of O/D and be back in second gear. 'For hot rodding around.' This ability was due to some simple electronic controls that would momentarily interupt the ignition alowing the control solenoid to pull the pawl from the sungear control plate. third and over was for economy, also some freewheeled on coast and could be a trick if you let your vehicle out run your brakes, not to good.
All I know is Chrysler books show it as automatic overdrive. Funny thing is you had a two speed automatic transmission on the rear of your manual shift transmission. I guess from now on we can refer to these a AOD Just like Ford. Hope this helps!

[rogerh]

Hi Ricky,
As said in my previous post, it's all about the language.
As an experienced and knowledgeable mechanic/technician, you refer to the O/D as an Automatic.
I am neither a mechanic nor auto tech. When I read the words 'Automatic', I think of Automatic transmissions, specifically the 3-speed Torqueflite my car uses.
Thank you for your "take" on the subject. I certainly don't mean to pick apart fellow members' remarks, based solely on my interpretation of the words.

[RICKYMOPAR]

Whatever...

[RICKYMOPAR]

Thank you, I found two useable units at my favorite price. If anyone is repairing one I have some Chrysler Plymouth service training books for information. Thanks again... Rickymopar

[Daniel Harris]

Hi Ricky,
Great to read your explanation on the way the O/D works, I am in the process of rebuilding mine and would be very interested in any books etc for more info. When I pulled my gear box down I found the sungear and shift ring were broken as was the control plate that you mentioned, I have replaced these parts and will hopefully have the gearbox finished shortly. I'm not sure how the O/D was treated (or maybe mistreated) before I got the car but I want to find out as much info on the operation of these units before I get mine back on the road so as not to run the risk of damaging the gears again. any info that you have would be much appreciated, ie: is it best to keep the O/D engaged for regular driving (city) or lock it out for city and only use it for highway driving? stuff like that I cant seem to find as the owners manual is very brief, Cheers mate,

[RICKYMOPAR]

Daniel. To be perfectly honest, everything has a cyclic life span. and yes it would be better to disable the automatic overdrive in town. As you well know the parts are getting a little difficult to find. I would definitly share some of my Mopar training manual information with you. I will scan the best and send you copied material to your email. The electrical controls with the exception of the governor unit and solenoid, can be substituted with new components we have today. it sure is funny to find out that most of todays automatic transmissions are finally electronic controled.