Re: [AMC-list] Classic OD

[Frank Swygert <farna@xxxxxxx>]

I've had several cars with the OD, and love it! Takes some getting used to. It's really an automatic OD, not manual. After about 32 mph you let off the gas and OD automatically shifts in, assuming everything is working correctly. Doesn't matter if you're in 2nd or 3rd (or 1st, but don't wind it up that much, may blow the motor!!). You SHOULD be in third though. As Tom said, you leave the handle in the "IN" position unless you're towing a heavy load or parking the car in gear. 

How it works isn't too complicated. Simplified, there is a big solenoid on the left side that looks like a heater blower motor. That presses a slide in that catches on a ring and locks the OD gear in place. Near the back on the right side 
is a governor that won't let the solenoid energize unless a speed of about 32 mph has been reached. There's another wire from the solenoid to a switch on the throttle linkage and to the coil. This is the "kick down" switch that kicks the OD off. What it does is cut the power to the solenoid then grounds out the coil, killing the ignition for just a split second. Killing the ignition releases power to the OD and allows it to drop out of gear. The switch is a ratchet switch -- as soon as it bottoms out it pops back into its original position, so the coil is only momentarily grounded. The OD won't come out if it has power applied to it. The power to the solenoid also runs through the kick-down switch. Inside there is a planetary gearset just like in an automatic trans. When the planetary gears are stationary OD is locked out. When they rotate the outer drum gear spins faster than the sun gear in the center (connected to the output shaft of the trans). The output of the OD is con
nected to the drum gear, so the output turns faster. The OD drive ratio is 0.70:1 -- the output shaft turns 0.70 times for every full turn of the driveshaft. 

Hmm... like Tom said, hard to type up and make it clear!! There aren't many thing that can go wrong in the electrical circuits. If it doesn't work let us know and someone will talk you through trouble shooting. 

As everyone else has said, the vac wipers aren't a bad design, they just wear out after 40+ years. You need either a vacuum booster pump or a vacuum storage canister to prevent them from slowing down too much when pulling a hill or accelerating -- I suggest both. If the seals in the motor are dried and cracked the motor needs rebuilding. You would spend about $250 to replace both with rebuilt parts and run new vac tubing. You can install a universal electric setup for $350-$400. 64+ models can be converted using factory parts, but old electric setups are hard to find in good condition. If you need a new electric motor you're right back up around $200 for a replacement or rebuild. You might be able to rig something from junkyard parts cheaper, I have, but then you're talking about a lot of time and some trial and error fabbing things to work. If you can, there's a little fun and adventure in doing it -- provided you enjoy such things like I do. Not enough to do it for someone 
else, but for me my time is free! 

---------
Date: Wed, 1 Jul 2009 09:26:43 -0500
From: Keith Evenson <epd@xxxxxxxxxxxx>

So I have never had a car with a manual over drive and I picked up a  
66 Classic that has one. How does it work? Another issue I am having  
is the vacuum wipers. They seem to work a little bit when I first got  
the car but not very good. Now they will go up but only go down when I  
shut them off. Any ideas?

--
Frank Swygert
Publisher, "American Motors Cars" 
Magazine (AMC)
For all AMC enthusiasts
http://farna.home.att.net/AMC.html
(free download available!)


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