Overdrive

I own a 39 Packard 120 sedan with overdrive. Can someone explain to me how the overdrive operates and the way it feels when you are driving the car with it on or off. I have the cable with the knob but when I push it or pull it there is no difference in how the car performs. The cable is moving at the transmission. It may be electrical but I am not sure. HELP!!<BR>Thanks,<BR>Arend

Not familiar with that overdrive tranny; however on the two overdrive units I do have (Borg Warner), they both are set for overdrive when the lever or handle is pushed all the way in. About 28-32 mph, a letting off the accelerator causes the overdrive to kick in. One one car it is noticeable while the other more subtle, but definitely obvious. Does your have a relay? On mine there are relays (on the firewall) and these have a fuse mounted with them. Also mine have four wires that connect from the relay to other points for the operation. Hope this helps a little until someone with a model like yours comes aboard.

According to my Motor Book, the 1939 is a semi-electrical system that uses a relay and solenoid. The soleniod appears to have 2 wires and is mounted on the side of the overdrive unit. Apparently there are 2 different versions, and early and late 39. The difference being the late 39 uses a reverse lockout switch and is wired through the ammeter and the early does not use these two components. Both use a relay.<P>Sorry I don't have a scanner otherwise I would copy the diagrams.

I want to thank both of you guys for responding to my question. I am going to go to the libary and get a copy of the Motors manual for the car and maybe it will help. It must be electrical because the cable is free and does push and pull correctly. I will keep everyone posted.<BR>Thanks,<BR>Arend

The wiring change Chris mentioned started with engine no.B318799A. If you have the reverse lockout switch either it or the kick down down switch will energize the solenoid and disingage the overdrive. Both the solenoid and relay are rebuildable if that's where your problem is. <BR>Have you checked the control cable to make sure the lever has full travel? You should have some clearance between the stop and the knob when engaged so it doesn't bottom out when pushed in. You could disconnect cable from lever on overdrive and check that it is fully toward rear of car (engaged).

The relays on my Studebaker and Kaiser models have a 25-amp fuse mounted on the front of the relay; however I have seen some with the fuse almost hidden underneath. And IF the relay is old, it is entirely possible that one of the plug-on terminals may have become desoldered and loose and thus not making contact.

I am not sure the library will have the Motor Book. Mine is from 1952.

REGARDING OVER-DRIVES<P>ALL of you guys are correct - as far as you went. Let's discuss WHAT those early over-drives did, and HOW they work.<P>The dash lever when pulled OUT, should lock out the entire system. All electrical and mechanical components of the overdrive are locked OUT. The car will be locked in direct drive. The typical final drive ratio of those years is WAY too low for normal highway driving today - at 55 mph your engine will be spinning FASTER than a modern car would be at over 100 mph. DO THE MATH !<P>When the dash leaver is pushed IN, the over-drive functions take hold.<P>The most dramatic MECHANICAL difference is that you are now in "free wheeling" - easy to tell if that MECHANICAL portion of the system is working, because if you take your foot off the gas to "coast", there will be no "engine braking".<P>At somewhere around 22 mph (depending on what version of over-drive, and the car's final drive (axle) ratio, the over-drive will "cut in", so long as the gas pedal is not more than about 1/2 down (most people "sense" when the over-drive is about to cut in, and take their foot off the gas during the "lock up")<P>You will know when you are in over-drive, because the car essentially shifts into a <BR>fourth gear. THAT gear is SO much higher than the "third" or "direct" gear, you will think you are in a whole different car, because "in over-drive", your motor will be loafing even at extreme speeds. To give you an idea, the typical over-drive equipped car in its DIRECT drive will be doing around 3,000 rpm at 60 mph, but in "over-drive", the motor will be spinning around 1900 rpm...<P>So - there you are...that is how it WORKS as felt by the driver. If anyone wants a further discussion on how it works mechanically and electrically, let me know.<P>Pete Hartmann<BR>Big Springs, AZ

'Freewheeling' ?????? The only freewheeling i am aware of has NOTHING to do with overdrive but rather with the CLUTCH mechanism of a std shift. When the gas pedal is released a vacuum belows pulls the CLUTCH disengaged. This is independent of any overdrive AND was available without o'drive. DO the O'drives offer a Nuetral position of something that i am not aware of? ?????

Yes, the overdrive when engaged allows the car to freewheel. I believe the 39 model has a higher cut in speed than the later models although it is adjustable with a pawl adjusting screw on top of the OD unit. The 40 and later models require changing the governor to change the cut in speed.

by 'freewheel' do we mean a complete disengagement of power flow from the engine to the rear wheels?????? If so, then there must be some kind of clutch or nuetral position with in the od unit itself????

The freewheel roller unit only works in forward motion under engine load. It is not engaging under deceleration (freewheel). Kind of like a bicycle that has gears operates.

Thanks everyone for all of the great input. I found out the problem. The car was always in overdrive due to a incorrect adjustment of the cable. The car works as it should now. <BR>Thanks,<BR>Arend

just out of curiosity, is your car operated in a very hot arrid climate???? Like maybe outwest in the desert area of Nevada or New Mexico???

thanks for the update. Must be a Sprag clutch inside the od unit. I never realized that the freewheeling is a function of od, but then agin i've not had much experience with od units.

No, The car is being driven every day in Maryland. I drive it in all sorts of weather , rain or shine. I have a garage queen 41 160 and then this 39 120 driver.

FREE WHEELING / for UnRegistered V-8<P>NOW I see why you are confused. The vacuum-powered release of the clutch was some goofy "stop gap" Packard came up with, until it came out with its own automatic transmission ( why Packard didn't join the rest of the industry and buy Hydramatic units for those owners wanting an "automatic", I dont know. A " Hyrda-matic" 356 ( '40 thru '49 "large" engined Packard) would have an equiv. flat-head Caddy with "Hydra-matic" for breakfast !<P>Anyway, getting back to that silly "ElectroMatic" automatic". THAT is what you are thinking of. There was a series of gas-pedal and vacuum controlled switches that would operate a vacuum-powered rod, that would pull the clutch in, saving the driver from operating the clutch during shifts. We had these on several of our late '40's Packards. I was able to get them working properly, but never saw the point in it. This has NOTHING to do with the transmission itself. <P>Now, another "pet peeve" of mine.....guys...listen up - there was NO such thing as an "over-drive" transmission. This simply reflected the times and preferences of the era - NO automible or transmission maker believed in those years that customers would accept a car that couldn't give good response in high gear at slow speeds. THAT is why ALL cars of that era were geared so horribly low, that they will pound their connecting rod bearings out in short order if you try and drive em at modern speeds.<P>There were three "exceptions" to this. There was the "Colombia" two speed rear end (there never was a version big enough to handle the power of the larger-engined Packards) which appeared as an option on some cars in the EARLY to MID thirties ( I have no recollection of when they stopped offering this as an "option", the Pierce Arrow (which had SOME kind of over-drive; what I do not recall) but THAT explained why a Pierce Arrow V-12, with roughly the same power-to weight relationship of a Packard Twelve, could do well over 120 mph, and, finally, the Borg Warner OVER drive, which was a SEPARATE AUXILARY gear box that went on the BACK of a machined recess of a standard three speed transmission. The Borg Warner is the one that had a provision, that when it was engaged, (dash-rod or lever pushed "in" ) with no power going thru it, would "free wheel", and, when the selonoid was activated, gave approx. a 30% reductioin in engine speed. <P>Pete Hartmann<BR>Big Springs, AZ

I'd like to add my two cents worth to the overdrive discussion.<P>I've driven a few and currently own two with overdrive - a 1953 Aero Willys and a 1954 Kaiser Darrin. They use the same engine and overdrive - Borg-Warner I believe.<P>The free-wheeling is operative ONLY when the overdrive control is engaged, and then ONLY before the shift into overdrive. Once the fourth speed is engaged, there is engine braking. When the speed drops low enough, in my case about 27MPH, the overdrive disengages and free-wheeling begins. <P>A three speed overdrive equipped transmission can be operated as a five speed transmission. Accelerate in second above the overdrive kick-in speed, take your foot off the gas and shift into second overdrive (now the third speed). Accelerate again to whatever speed you like and shift to high (now fourth speed) and immediate floor the accelerator. This will shift out of overdrive to conventional high or third gear. When you take your foot off the gas, it will shift again into overdrive (fifth speed). <P>The sequence is 1,2,3,5,4,5 as the shift from overdrive second is to overdrive third, then back to conventional third (flooring the accelerator) and finally to top gear when you back off the accelerator. <P>For greater engine braking from cruising speed in overdrive, floor the accelerator (kick down to conventional from overdrive), pull out the overdrive lever and take your fooot off the gas. If you pull out the overdrive lever before accelerating in conventional drive, you may have real problems.

Friend Bernardi has described OD operation precisely. You can get a double-pole double-throw switch, mount it on the column and reroute the wires from the kickdown switch to the new DPDT and activate it W/O the necessity of flooring the accelerator, but you have to remember to keep feeding the gas so the engine is pulling, not acting as a brake. Makes his fancy shifting that much easier.

yeah, if i remember right, thats the way to shift hwy tractors with the 2 spd axles. BUT, the hwy tractor has no overrun (freewheeling) that i know of.