O/D Operation ????

[Deleted User]

Just so I understand the book correctly..................

To use O/D, I pull the knob under the dash OUT, drive normally to get up to speed (30 plus), depress clutch, press gas pedal to push kick down switch (hope I hear a click and engagement of Pawl in OD), lift gas, engage clutch and should then be driving in 3rd gear OD....do I have this correct?

It would seem I have a bad part (or parts) somewhere as I did not think I ever had the OD kick in. i will be starting the check procedures in the Service Manual but I wanted to walk through the Operation procedure to make sure I am trying to engage the OD properly.

DocHornet

The O/D knob should remain IN for normal overdrive operations. You only pull it out if you want to DISENGAGE the normal overdrive function.

For normal operation, just accelerate to around 30 or above, when you let off on the gas the O/D will shift into the cruising gear automatically. To downshift (if speed is not TOO high), just push the pedal all the way to the floor. Unlike an automatic tranny "passing gear", once you've downshifted out of Overdrive, you can relax the throttle position. It will remain in the lower gear until you fully let off on the throttle.

I've racked my brain, and can think of but few reasons for ever disengaging the O/D (pulling OUT the knob). I don't think I've ever seen the need.

By the way, keep in mind that with overdrive-equipped cars, the transmission is in free-wheeling mode until the final O/D gear is engaged. Generally, this means when you stop and park, the rear wheels are NOT constrained by an engine connection, except if in reverse gear.

As a matter of practice, I always make sure I shift into reverse when parking, and set the handbrake as an extra precaution.

These are wonderful, generally trouble-free systems. A shame they still don't offer these overdrive units in today's cars.

[Deleted User]

Thank you, DocHornet. I think my system is OK then as I was driving with the knob pulled out.

I will try again tomorrow afternoon with knob pushed in.

I looked at the wiring diagram again and I do need to confirm that I have the wires properly installed in the Reverse Lock-out switch. I may have them reversed.

Park_W

The switch doesn't care which way the current goes through it.

Geoff

When driving in mountainous country it pays to disengage the overdrive before descending a steephill, if you want engine braking. Sometimes you have to anticipate well ahead, as once you are in overdrive the only way to disengage is to either kick-down, or slow down until it drops out, and you can then pull the o/d knob out. You cannot pull the knob out whilst o/d is engaged at above cut-in speeds.

[Deleted User]

OK.....I have the OD engaging so I get the free wheeling but I am not real sure I have it at highway speeds.

I would appreciate any Operator tips and techniques you may have to share.

Geoff

Free-wheeling is only before the o/d cuts in. Once o/d is engaged you have engine braking. With the o/d control pushed in you can take off in low gear in the normal manner, and can then change gears up or down without depressing the clutch, until cut-in speed is attained. In practice, you really only use the o/d facility in top gear normally. I would not recommend using the kick-down facility too often, as I have seen the input shaft starting to corkscrew. Kicking down puts quite a strain on this shaft, as you instantaneously drop the speed 30% with full power on, and this is all on the input shaft. Probably not quite so bad with a 232 motor, but with a 308 it's quite a bump. Don't be alarmed at a whirring/crunching sound sometimes when you pull the o/d control out at low speeds, just press the accelerator and it will synchronise itself. Once you get used to driving with o/d you will never want to go back to driving without it. Good luck, and have fun.

SuperDave

If you have a single lever transmission with OD, you may need to pull it out of overdrive to prevent it from jumping out of reverse. I have tried all the tricks but some transmissions do not like to stay in reverse while the OD knob is in. I found this jewel of information in the Official Hudson shop manual. My 49 Super six was a problem even after a transmission swap. all new linkage bushings, and removeing the lockout switch (which is redundent), Also a few other unauthorized adjustments. Now.. my 49 Commodore that has the linkage installed for drive master is bettter behaved. Don't have clue why.

[Deleted User]

I agree about the kick down feature too Geoff . Never did like the idea of momentarilly killing the engine at full throttle . Thats what the switch does it shorts out the coil if I recall correctly.
That allows the overdrive to drop out ,just seems like a lot of stress on everthing to me. I dont hook mine up that way , but thats just my preferance,
Roger

[Deleted User]

So, as long as I have the knob pushed in and have free-wheeling at lower speeds, when I get to 25MPH and shift into 3rd gear like normal I will actually be in OD? Am I understanding the operation correctly.

My Pacemaker cruises nicely at 25 mph in 3rd gear.

Roger, I would like to see your wiring diagram so I can see what you mean.

[Deleted User]

With the knob in you shift normaly ,1 ,2 ,3 and at about 20-25 mph the speed switch will have closed and pulled in the overdrive relay. At that time with the relay being energized it has also sent power to the big solenoid on the transmission. Now you are driving in third gear with the overdrive circuit active -just let up quickly on the gas pedal and the shift to overdriver should happen. It will be obvious when the gas is reapplied you are in a higher gear.
Depending on the ammount of of wear you may not "Hear" anything. I have a 47 with about 10,000 miles on it and it goes in with no indication of any kind.
I'll try and draw something up for you if you wish - wiring wise tommorow,
Roger

DocHornet

Pacemaker,

You shouldn't be concerned about the reverse lock out switch (at least as regards the O/D). Honestly I'm not even sure what that could be? Perhaps a starting safety switch to insure you are in neutral?

But, in any case, there is nothing electrical about the reverse lock out portion of the overdrive.. it's all strictly mechanical... little sliding arms and pawls and such when you select Reverse with the shift lever.

[Deleted User]

I take it then that if the knob is pushed in and I shift from 2nd to 3rd above 25 mph.....that the OD could be engaged as I lift the gas pedal during the shift and I might not notice anything.

So, to truly check one would need a tachometer to see if the RPMS are really lowered.

[Deleted User]

Rick, I am not sure I understand you correctly. If the OD knob is pushed into and I shift normally - when I lift off the gas pedal, I will be in free-wheeling mode and the engine should drop RPMs like I was sitting still. As long as I did nothing and inadvertently activated the kick down switch. (Still not sure how the switch works in all this).

If the OD Knob is pulled out, and do the same, I should get a heavy load on the engine as in Engine Braking.

[Deleted User]

Rick, I greatly appreciate your help. I look forward to meeting you at Marbury Motors Days in two weeks. I just sent in my RSVP.

[Deleted User]

Mentioned above that the reverse lockout is not required ,this if not so. The mechanics of the overdrive unit are such that it "WILL NOT GO BACKWARD" . To the extent that if you were stuck in overdrive and on a hill it would act like a "Hill Holder" and the car would not roll backward.
And if the overdrive were energized in reverse and engine power were appiled total destruction would result, it is there for a reason leave it out if you want,
Roger

[Deleted User]

Roger, I do not plan on doing that. But I am interested in the Kick down switch and how it works in the system.

For example, if when doing 65 on the highway and limit allows 70, one presses a little harder on the gas but that action is all that it takes to engage the kick down. So then the OD is supposed to disengage, correct? But what if you still want it at that speed yet the gas pedal and kick down spacing do not allow it? Slightly far fetched but this is how I learn.

SuperDave

Roger, You are right. If the solenoid pawl is stuck "in" The car will not roll backwards. I did have this happen one time..(in 40 years,) but it was a problem at the time, because the front wheels were against a curb in front of a shopping center. I have to mention that there were a lot of internal problems with that OD that percipitated that problem. I've been driving my 49 Super for 8 years with the switch removed..
I wouldn't recommend driving in reverse above 25 MPH ! LOL...

bartibog1

if you are driving down the highway at at 50 mph roughly how many rpm would you expect the motor to be turning while in o/d
steve

ernie28

PM500, I have found that to make the kickdown switch activate it takes a deliberate harder press on the gas pedal. On mine you can press the gas pedal to full throttle but it takes another extra bit of pressure and you feel the switch being depressed - then it works as it is supposed to.

[Deleted User]

To "Kick - Down" using the throttle the pedal must be mashed comletly to the floor . Not just pushing harder at high speed . The switch must contact the pedal then it shorts out the ignition momentarily and drops out O/Drive,
Dave ,I also had one "Stick" and it was in a parking spot with a curb in front. No other car in the world but a Hudson 8 would have the torque to go up over 10" curb in what ammounted to 2nd gear. It was first gear in overdrive.
Car would not go back and I knew better than to force it . Only choice was to go forward and over the curb . What had happened was the soleoid had come loose somehow and got unhooked inside the transmission. Reinstalling the solenoid and tightening the bolts took care of the issue.
Roger
Roger

[Deleted User]

OK. Great to get all this information.

So, at what speed can I NOT push in the OD Knob without hurting the system?

Can I hit the highway, get up to 55, push in knob, lift off gas for a second and then get back
on it" ?????

Geoff

You can push the control in at any speed. But you have to lift your foot off the accelerator pedal to get the o/d to click in.
What you cannot do is pull the control out once o/d is engaged. You have to either kick-down or slow down until govenor points open.

[Deleted User]

Geoff, Thank you. That is what I needed to know.

53jetman

I have always pushed the OD control in, and just drove the car normally - going thru the gears and then once in third simply run the car up to 25 to 30 mph and lift my foot. It goes into OD automatically. I've never understood why some folks want to fuss with the OD control cable! The OD control is always pushed in on my cars - I never touch it.

J Haugo

53jetman-
Keep in mind that if you are parked facing downhill the car will not be held back by any gear but reverse. If you ALWAYS have the OD control in, you should ALWAYS leave your car in reverse gear.

53jetman

Tell me, what is the emergency brake for? ? ?

[Deleted User]

For parking ,for just that reason,
Roger

Geoff

It's not a good idea to leave the hand brake on except for short term parking. Leaving it on whist parked long term just puts strain on the cables, and there's a likelihood of the shoes sticking to the drums. I'm the same as Jetman, and leave the o/d control in all the time, except for when I am descending steep hills when I want more engine braking than the high gearing of the overdrive allows. That is on my Jet. However on the Hornet I have a slight problem in that the reverse gear does not engage with the control knob pushed in, so I have to pull it out to enable the car to reverse. Too much trouble to pull it apart to fix it! This is a single lever box, whereas the Jet is two-lever.

SuperDave

Geoff, Pulling it apart won't fix it. It's just the way it works. . LOL
Dave

Park_W

SuperDave, the problem you describe is due to a weak detent spring for the low-and-reverse shift rail. The OD trannies are supposed to have a much heavier spring so they can resist the push on the shift rail that you get when in reverse. Sometimes these springs get accidentally replaced with a non-OD one or they just get weak. Al Saffrahn has had some good ones made. The bad news is that you have to remove the tranny top cover to replace the spring.