OD Testing and Usage

[Deleted User]

Park W wrote:

Mars was referring to the large OD cable button under the dash (or on the dash in '48-'49, I think). Having that button IN corresponds to the lever down on the OD unit being in its rearmost position (i.e., overdrive enabled, not locked out).

Thank you. I have a lever, for all intents and purposes.



So, I use a wire and check that the relay and solenoid both activate per Mars55.



How do I test the switch under gas pedal? I have seen here that some people move the switch.



Then, how do I properly drive the car using the unit?

Jon B

To test the kickdown switch under the accelerator: with the ignition turned on and the overdrive knob pushed in, "floor it". You should hear the "click" of a solenoid somewhere under the dash. At least, that's how it works on my '37!



Operation: Be sure the overdrive knob is pushed all the way in (this "enables" the overdrive system, but does not actually engage overdrive. When you pull the knob all the way out it "disables" overdrive so you are always in conventional 3-speed mode.)



Whe the car reaches a speed of between 25-35 mph, and you're in third gear, (exact speed depends on how your OD control is set), release the accelerator briefly. There should be a quiet "click" as the overdrive engages and you move into fourth gear.



You'll notice the car is "free-wheeling" at this point; it doesn't suddenly decelerate as you lift your foot, as it normally would in any other manually-shifted car. That's why you DON'T want to have that OD knob pushed in, in hilly areas. The engine will no longer work as a brake for you as you come down the hills, and you'll "fade" your brakes, and take the road to perdition.



Now that you are in overdrive (fourth gear) drive normally. If you need an extra burst of power (to pass someone, for example), "floor it" and you'll kick down into third gear automatically. If everything is working okay. Then, when you've finished passing, release the accelerator once more and you "click" back into fourth gear.



When you slow down to under 30 mph (give or take a couple mph) your transmission will automatically shift back into third gear. You can put it back in fourth again by speeding up, and releasing the accelerator again.



Or you can lock overdrive out (if you intend to be driving in the city at low speeds, and don't want "free wheeling" by pulling out the OD knob. I can do this as I'm driving (often I have to accelerate a bit to ease the transition), though some folks say you oughtn't to do it until you're at a dead stop.



End of lesson.

[Deleted User]

You can go to the following link and download a complete OD manual. This manual applies to your OD unit and its operation. There are also overhaul manuals at this and other sites.

http://www.tocmp.com/manuals/trans/Borg-Warner%20Overdrive/index.htm

[Deleted User]

Thank you both. That is the exact type of response I need. Both are very clear and concise.



I guess too many years in the Army has left me needing all my manual to be at the 8th grade reading level.



Rep points for all.

Park_W

Jon, the KD switch test you outlined only works on the '40 overdrive units. On the '41 and later ones, you have to ground the wire at the governor to make that test. Grounding the governor wire should cause the relay and solenoid to click on; then pressing the KD switch will break that circuit, so you'll hear the relay and solenoid click as they "de-energize."

mars55

On further review you should check that the governor wire is hot with a voltmeter or test light. On later stepdowns you have to disconnect the wire at the "A" terminal on the generator and connect the loose wire with jumper wire to negative terminal of the battery. On '48 - '49s the OD is connected to the "B" terminal of the regulator and hence to the battery. On the later stepdowns the OD is connected to the "A" terminal of the regulator. Not sure how a '50 is connected.

Clutchguy

The governor only provides a ground for the O/D system.

Unknown

so in theory, I can remove the solenoid, and check it per the manual specs, and the govenor, right? neither of these items are too difficult to remove, and at that point, I can eliminate the two main components on the trans? if my OD still doesn't work, and these two test good, it is either a relay, kickdown, or mechanical, huh?

[Deleted User]

SuperDave wrote:

I wouldn't recommend trying to see if the OD will kick in with the car on jack stands. Very dangerous and noisey!. You should be able to find a thread on how to drive the car in and out of overdrive. As Park says, the knob under the dash pushed in is "in" OD... pulled out , it's "out" of OD and acts exactly like a simple three speed. You will love it.

Your concern is noted and I am sure shared by others.



Short of taking the unit out, I am interested in finding methods to test the eletrical components. More a quick diagnostic before one would pull the transmission.



If they test bad, then I can plan to replace them next winter (removing the entire transmission if needed). And I can just drive it as a normal 3-speed (as you noted) until that time.

Clutchguy

so in theory, I can remove the solenoid, and check it per the manual specs, and the govenor, right? neither of these items are too difficult to remove.

HK,this is correct. The governor unscrews,and also is supposed to have a brass washer under it,kind of like a gasket. Once you have removed the governor,take out your multimeter,turn it to continuity[tone mode if equipped]chuck up the end in the varible speed cordless drill and spin it.[when I say the end-I mean the little tip-not the gear] Does it work when you are touching the O/D ground post?,if not,pull the cap off and look at what might be wrong.Most of the time,the centrifical weights inside are all gummed up and this what prevents it from proper operation.Look closely at the fiber board with rivet type connections on the top.If these are loose or broken,it probably will not test out and could be the problem. The solenoid has some of the same type of problems.If you jump the big post to power-with the solenoid bolted to the trans.[50 and up]it should work[loud clicking sound].If it doesn't,remove the solenoid from the trns and proceed to bench test it. These get gear lube in them and can cause the points to gum up with burnt gearlube and it makes no contact-thus the O/dr.does not engage. These are only a few things that go wrong,but are the easiest to check and the quickest.

mars55

Clutch guy wrote:

The governor only provides a ground for the O/D system.

Ah, that is true, but if the governor switch is open then the battery voltage will appear across the open contacts.

Clutchguy

mars55 wrote:

Ah, that is true, but if the governor switch is open then the battery voltage will appear across the open contacts.

This is also true,but your reading it and not applying it.A test light will not light from the governor wire. Usually when I'm checking the components,I am verifying that they will work and I'm doing so on the bench. Factory '50 and up must have the charging system energized to work. If you have added the O/Dr. system, from the relay,it needs a power wire from the battery that has circuit protection[fused],a switched power supply[keyed from ignition] a ground[governor]which in turn makes the solenoid terminal #4 and with the O/Dr. lever pushed in,should make the overdrive engage.

mars55

A test light will light from the governor wire if the car is a '48 - '49. These cars have OD power wire connected to the "B" terminal of the regulator which is connected to the battery. The other stepdowns have the OD power wire connected to the "A" terminal of the regulator. When I suggested this test I did not know if the '50 was hooked up like the '48 - '49 or like the '51 - '54 and this test would find out. You can verify the operation of electric part of the '50 - '54 OD on the car by disconnecting the "A" wire on the generator and then connect the loose wire to negative terminal of the battery. Once this is done, grounding the governor terminal should cause the relay and the solenoid to click provided the OD control is pushed in and the transmission is not in reverse.