I have a manual 3 speed (column shift) with overdrive ('52 truck). Overdrive consists of a pull knob under the steering wheel (currently pulled out) and an electric switch. The PO explained its operation to me but I suspect he was not absolutely sure either. Is there a manual or instruction sheet on how to engage and disengage the OD, when it can be used, when it should not be used (I assume in reverse). What is the sequence for using the pull knob and electric switch to engage and disengage. Basically a how to. I understand it is a great thing to have, especially for higher speed driving, so i don't want to mess it up figuring it out by trial and error. Thanks for the assistance.
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The truck wasn't originally equipped with "an electric switch," Marcus. If it has an electric switch (like a toggle switch) within the cab for the driver to use, it is undoubtedly a governor override (by-pass) switch that allows overdrive to be used at speeds lower than the usual governor cut-in speed of about 30 MPH.
To see if the overdrive is working at all with what appears to be your setup, do these two things before starting the engine:
1. Push the big overdrive knob IN all the way against the stop.
2. Place the electric switch (the one that's been added) in the OFF position.
Start the engine and go for a drive. Get up around 30 MPH in third gear, let off the gas, and flip the switch to the ON position.
If the overdrive is working as I suspect it's been modified, your should hear and feel a slight "clunk." Push back down on the gas pedal after you've heard / felt the "clunk" and the truck should resume road speed with the engine going noticeably slower (fewer RPMs even though the road speed is unchanged).
When you are done where you're going and come back down from a road speed above 30 MPH, flip the toggle switch to OFF and the truck will drop back to straight third gear...or should.
The best advice from this point is to buy and study a copy of Randy Rundle's OVERDRIVE book from Fifth Avenue Auto Parts in Clay Center Kansas, advertised in every Turning Wheels. Study the book and you will see how to eliminate that switch on the dash and restore the truck to operating as designed, which will eliminate that switch and make the whole unit as "automatic" as it was originally.
It may also be that the governor is bad and needs to have the points inside cleaned, or the governor replaced. With the governor working as intended, you'll not have to contend with that "electric switch" on the dash and the truck will be easier to drive.
If you ever want to drive the truck as it if had no overdrive transmission, just pull the big overdrive knob out all the way when you are stopped, whether or not the engine is running. Then it will act as if it has a straight three-speed transmission.
Others will likely add more to this discussion, but that's a good primer for now.
BP
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With the knob pushed in, lifting off the accelerator will engage the OD at any speed above about 30 mph. It will work on 3rd, 2nd gears, and even on 1st, although I don't know why you'd use 1st OD. Flooring the accelerator will disengage the OD, creating a ,ummm, passing gear. Lift off and it will drop back into OD.Originally posted by BobPalma View Post
You don't actually have to be stopped to lock the overdrive out. Floor the accelerator and the car will, if the OD is operating properly, disengage the OD. You can pull the knob out then.Comment
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The most important thing to remember is to only push or pull the overdrive knob while the vehicle is stopped or when the engine is lightly pulling the vehicle while it's out of overdrive. Follow this one rule, and there is no chance of causing damage to the tranny or overdrive.Last edited by TWChamp; 09-21-2018, 07:28 PM.Comment
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Thanks for the replies. Bob, my overdrive functions as you describe, or at least as explained by the PO. He pushed in the knob to I guess allow the OD to function, then took his foot off the gas and toggled the switch to engage the OD once his speed was up over 30mph. It would only disengage once he toggled the switch to off. He did push the knob in while driving however. This contradicts what TWChamp has written. I've read elsewhere that the knob can be pushed in when stopped or when moving. If so can the knob be pushed in when going faster than 30mph? Or does one need to be stopped?
Personally I would prefer the OD functioned as it was designed, without the on/off switch. I have ordered Randy's book so I can hopefully return the OD to its original operation. As I understand it if the knob is pushed in, the OD should automatically engage once the speed exceeds 30mph and you lift your foot off the gas for a moment to allow it to engage? Is this correct? The knob should always be pulled out before reversing? Or is that incorrect? If the OD is switched on with my toggle, is there any damage if it remains in OD even if I drive the truck slower than 30mph, or use lower gears and even when stopped? As I mentioned, I don't want to mess it up before I've has the opportunity to enjoy it.Comment
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I never touch my overdrive handle, just leave it in.Comment
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That's the way to do it.Originally posted by tim333 View Post
You do NOT have to the pull the knob out to go into reverse. There is a rod inside the transmission that moves when the shift lever is moved into reverse and accomplishes the same function as pulling out the knob.
You should always park the vehicle in reverse. That automatically locks the overdrive out so the car will not roll, plus it is the highest ratio difference.
For 99% of normal driving, just leave the knob in and forget about it.Last edited by RadioRoy; 09-21-2018, 07:35 PM.Comment
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OOPS: 'had to add something here because words are required here to meet the minimum for a post.Originally posted by my2R5 View Post
BP
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Just ONE more important Overdrive issue to understand, after Bob P's good instruction.
It is fine to always leave the O.D. handle pushed IN, however just know that you MUST always get in the habit of parking the Truck IN REVERSE! That way, it does not matter if you left it IN O.D. or OUT, it's safe.
Do this methodically just like putting an Automatic in Park when parked!
If you do not, there is a good chance the truck will roll away, get bumped and roll etc, since the Transmission is in "Freewheeling" and will not hold the Truck from rolling when in Overdrive below 30 Miles an Hour.Last edited by StudeRich; 09-21-2018, 07:26 PM.StudeRich
Second Generation Stude Driver,
Proud '54 Starliner Owner
SDC Member Since 1967Comment
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Reread #4. I did not say you can't move the knob in or out while driving.
I do it often, especially when going from highway to slower city driving, where most of the driving is 35 or less.Comment
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Yes you are correct TWChamp. Although I have read it several times I kept reading it the same. I see what you mean now.Originally posted by TWChamp View Post
Thanks everyone for your comments, I feel considerably more confident in using the OD now and knowing how it functions. I will most definitely see about getting rid of the switch. My memory is not what it once was and I will undoubtedly leave it in the "on" position and try and use reverse.Comment
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Don't you need to toggle the solenoid "off" while accelerating flooring it (assuming the kickdown switch is there and functioning) ?Comment
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I'm wondering if the toggle switch was added in place of the overdrive governor, or was it added in addition to the governor?
If in addition to the governor, then he added it to be able to use overdrive at speeds below 30.
The reason for pulling the handle out when most of the driving is below about 35, is so you have engine braking. This is important when going down a steep hill.Comment
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There is one more thing to ADD....
My truck has the same modification with the OD switch a simple toggle switch to activate the solenoid.
IT WILL NOT GO INTO REVERSE WITH THE SWITCH ON. It's embarrassing, but I've done it.Comment
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When I was a fearless teen I had an over drive vehicle and I relocated the kickdown switch inside mounted under the dash. I could create 5 forward speeds, first, conventional second, second overdrive, then between second overdrive and high I would push the button and be in conventional high then into high overdrive. I am not that dexterous any more but it was fun then. I also had the starter button hidden and an obvious looking starter button with the horn attached to it, the police didn't like it but it was a legal horn, they felt I couldn't get to it fast enough, maybe not today but I was fast then.
An additional note when wiring in the OD kickdown switch, when in operation it momentarily opens the ignition to relieve the pressure in the transmission for it to shift. This function takes about a couple of milliseconds, between two contacts that are about 1/8" apart, but this is a very important function for a smooth shift from OD high to conventional high.Comment
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