View Full Version : Transmission: Overdrive operation

05-14-2018, 08:59 AM
New to Studebakers and first time with an electric overdrive option on anything, I'm still a bit stymied by the Owners Manual description for the OD operation.

Selecting the OD from a standstill in neutral (pushing in the cable and switching on the relay (P/O installed as a reliable bypass)), I did verify last night on a test run that it worked great, shifting silently into "4th" once I lifted off the pedal at around 38-40 mph.

But my question is this: can I not leave the system engaged while in town (occasional stop and go), or if my route can slow higher speeds can I later decide to select the OD on the run without damaging anything?

Manual describes how to kick it out (by full throttle) but isn't clear on when the OD can be selected, other than from a standstill?

Stupid questions, I know. Just looking for good advice - thanks.

05-14-2018, 09:28 AM
The main drawbacks to leaving the OD pushed in are lack of compression braking at lower speeds and not having compression to park unless you remember to park in reverse. Never try to pull the lever when the OD is engaged. This will ruin your transmission. It is possible to drive most anywhere up to 45 in 2nd gear just using direct and 2nd OD. Practice will give you a feel for it. It is a great accessory. You can push the lever in anytime while operating the car to allow the OD to be engaged. You would then have to let off the gas to engage the OD.

05-14-2018, 11:24 AM
Nothing wrong with leaving it in overdrive around town. In fact that's the preferred mode, unless your town is very hilly, and you need the engine braking. Because it freewheels below the OD cut-in speed, you can shift without using the clutch pedal. 38 - 40 mph is an unusually high cut-in speed for overdrive; it was usually around 27 mph. Makes me wonder if a previous owner installed the OD in a car that formerly was without. Overdrive cars normally got an axle of about 4.10 ratio. If you had overdrive with a 3.07 gear, as used behind an automatic, you might get a cut-in speed that was higher.And you can pull the OD handle to lock it out, while driving, as long as you do it when the transmission is in direct-drive mode, and the engine is pulling. Typically, when kicked down into third direct upon cresting a hill, and you want it locked out for descending the steep grade on the other side, or when accelerating gently in direct drive below the cut-in speed. In these instances, pulling the knob just mechanically duplicates the condition that was already established electrically, and there is no conflict between moving parts.

05-14-2018, 12:06 PM
As I explain to my customers, you can bring the OD in any time you want, but you can only lock it out--by pulling the knob--when it is already out.

05-14-2018, 12:29 PM
I assume you mean leaving the bypass switch for overdrive turned ON and the overdrive lever pushed in while in town.
That will be fine and you'll just be driving like you have a 3 speed car with a high speed rear end, about 3.28 or so, if your rear end is 4.56, like my 1950 Champion has.

BTW, I hope power to the bypass overdrive switch is turned off when the ignition key is off.

05-14-2018, 02:34 PM
I have 3 speed w/OD and use it constantly. True, you don't have any compression in 1st gear but you do have compression in 2nd and 3rd. Driving around town I almost NEVER put it in 3rd. I can drive 45 to 50 compfortably. Also, I can put it OD while moving. I Just push in the clutch shift gears and push in the handle. Easy money. But I would not try taking it out until stopped.:!:

05-14-2018, 03:08 PM
If you have a modification to the original electrical circuit(s): be aware that you no longer can follow the manual or BW operating instructions !!! Most "bypass" switches simply enable the solenoid to engage the OD no matter what speed, and with the handle pushed "in". To operate the system with this modification could cause damage to the tranny.... I've done this on a 59' wagon but cannot remember the safe procedure for it.

05-14-2018, 05:06 PM
Yes - the "bypass" is no longer hot when ignition is switched off. Thanks for the double-check.

05-14-2018, 05:31 PM
Thank you to all for the amazing responses in such a short amount of time. I arrived through Minn-St. Paul International this morning, posted my question waiting for baggage, and by the time I finished my work here in Wisconsin, I was amazed to see this much assistanc... an AMAZING technical forum to be sure.

Yes it would appear that the OD was added, so without checking ratios, the cut-in speed may in fact be higher than OEM, but having only tested it once, the 38-40 mph I trialled was just one data point.

Based on all the conditions folks above mentioned for when to cut-in and cut-out, I can only imagine that things got confused and parts got injured along the way. Driving in different terrains with rain or other distractions, mistakes happen and I just can't see this being a better solution to Studebaker or Borg-Warner having experimented with a fourth speed or alternate ratios. It was a different time I know, but the system was not bulletproof from where I'm reading.

I like the option mentioned by "mapman" and others to try remaining in OD around town and getting a feel for 2-direct and 2-OD....but in general I'm nervous enough I may only use it when knowingly heading out on the highway. I'm a 45 mph guy in my Champion with my OEM brakes and interesting take-up/pedal feel!

Thanks again everyone.

05-14-2018, 07:54 PM
Fwiw, the OD on my 64 Champ 8E7 is original, and the cut-in speed is at least 35 mph (according to the OE speedometer).

05-15-2018, 02:53 AM
With a 3.54 rear axle I always just left the OD lever pushed in. I'd start in 1st, shift to second, when ready to shift again just lift off throttle a bit and it shifts into OD. 2nd over was perfect for in town or anything under freeway cruising. I'd pull onto the freeway in 2nd over all the time, then realize I had one more gear and shift into 3rd at freeway speed. For me there where was never a need to lock out the OD. The only time I ever "kicked it down" out of OD was on purpose just to see if it worked. As for "no compression braking" it didn't seem any different than driving any "modern" automatic trans car to me.

05-15-2018, 08:16 PM
Good advice - I like the concept of a free upshift as needed on a highway!

Assuming I coast down from 3rd OD, when I clutch and downshift to "2", does this remain "2nd OD" if I stay above some threshold road speed?

05-15-2018, 08:40 PM
Yes, as long as you are above the governor switch speed and don't floor the accelerator to kick it out of overdrive it will remain in overdrive.

05-15-2018, 08:49 PM
Thank you sir!