overdrive questions (borg warner)

Dave in Boise

Dave in Boise

Senior Member
Hi All,

I am considering putting in an older Borg Warner overdrive into my touring A and was wondering what advice you had on the Borg Warner units? I know they are not as nice as Mitchell units, but it's what I have at the moment.

I hear that they will freewheel in high range down hills and that they can lock up or break when reversing unless locked out.. Any thoughts on how to make this a bit easier to set up and operate?

I am looking to be able to OD 2nd gear on demand for climbing 5-7% grades like we have in this area and OD 3rd as needed.. not for higher speed but to make it easier on the engine at 50-55 or so.

Appreciate anyone's feedback ;)

- Dave in Boise
 
Ditto on what Mike V. Florida said. I've got a BW O/D in my '29 roadster and I like it. It took a real learning curve to be able to operate it correctly. More then once I shifted into reverse without disengaging the O/D. Realizing what I had done immediately after releasing the car's clutch and it didn't move.:eek: This is the biggest "No-No" you can do to a BW O/D. It is suppose to strip the O/D's gears, but for some reason it has not done it to mine. My car cruises comfortably at 55 or better. The only upgrade to the motor was a lightened flywheel. Florida is mostly a flat state. However, where I live {west central part} they are some actual hills! I have yet to drive the car on these roads and would feel leary
of using the O/D on them. Lugging my car's motor with an O/D going up a hill is not something I want to do. I think more of what you are wanting is the Mitchell gear-splitter type O/D. If I get an O/D for my other "A" it will be a Michell.:)

Bob-A:D
 
I had one for a short time. Biggest gripe was lube running from the BW down into the differential. It slung out onto the rear wheels after quickly overfilling the diff. It was old needed some work and cranky to use but helped flat land cruising. Just too many issues and problems overall. Took it out and went back to a stock set up. Haven't
looked back !!!
 
Go on line to www.ocmafc.com (the web site of the Orange County Model A Ford Club of Southern California). On the menu at left scroll down to "tech articles" and click. It will bring up a new menu. Click on my name at the top (Tom Endy) and it will bring up a series of articles. They are all adobe files and you are welcome to download and use any of them.

There are several articles about the Borg Warner overdrive you are welcome to download and use.

Tom Endy
 
Thanks Tom.. I have downloaded your articles and will be studying them..



Is it true that the OD will freewheel when downhill, and you should shift out of OD before coming down a steep grade?

I am thinking if I can go up some of these hills with the car in 2nd and overdrive, I should be able to run 35-40 and not lug the motor, but then would need to shift out of OD at the top of the hill to have gears to hold the car back on the downhill.

Does the cable engage/disengage the OD into the system? (or lock the OD out)
What does the Solenoid do? The same thing?

So to engage, I would have to move the lever/cable into the right position, and then turn on the solenoid electrically to engage the OD into service, and then turn off the OD electrically to get back to normal drive (and have gears for downhill cruising).

The lever and cable should be moved to disable when reversing?
I'm just wondering how one operates these sort of OD's and if they can be used as a gear splitter if the speed control solenoid is not used?

- Dave
 
The pull cable operates a lever on the side of the overdrive housing. When operated it engages the over-run clutch. and puts the wheels in a free wheeling mode. It also sets up internal hardware to accept the solenoid pall when electrically operated.

When the pull cable is engaged you cannot back up. If attempted there is no damage done, you just don't go anywhere. An over-run clutch only works in the forward direction

With only the pull cable engaged you are not in overdrive until you power the solenoid. When both are engaged and you attempt to back up you can do damage to the overdrive depending on how aggressive is the attempt.

You can climb a grade in second gear overdrive when both the pull cable and the solenoid are activated. When coming down a grade remove power to the solenoid and deactivate the pull cable or the car will run away with you.

When you have fully digested the articles you have downloaded you will see that you can connect the solenoid power through the governor attached to the overdrive (if it was left in place by the person who modified the unit for a Model A). The governor is a simple switch that closes at about 25 mph and puts ground on a power relay to allow the solenoid to be powered. At speeds below 25 mph the switch opens and drops the solenoid out. This does two things for you. It prevents you from backing up with the overdrive fully engaged. It prevents your battery from running down if you park the car and forget to turn the solenoid switch off.

Tom Endy
 
Thanks Tom :)

Sorry if I am asking a lot of obvious questions here.. appreciate everyone's patience..

I will likely hook it up through the governor as you indicate to keep it from being engaged at rest and in reverse. Are the governors adjustable as to when they kick in?

Last question (for now) is for the engagement.. is a cable the best bet here, or have there been levers used to actuate them? Was thinking I could offset a second emergency brake lever as the actuator for the traditional cable engagement?

- Dave in Boise
 
FYI....Free Wheeling or use of a run over clutch was BANNED in the early 1930's due to cars failing to brake well (no engine braking).

I would not use this device.

Marc
 
I have had quite a few of those B.W.OD units,but only one in an A.I put the truck together with it,ran it around town,went back to the shop and removed it.It worked great but it was a 33% over unit and it was too much for what I needed.Mine had been built with cable controls,doing away with the electrical parts altogether.While it worked nicely it did not lend itself to split shifting like a solonoid operated unit would.I had a bunch of these in 55-57 Chevy's over the years.I liked overdrives and I installed them in most of those that I bought.I never wired everything up,I just ran them with a toggle switch.They were all free-wheeling,and Ford used them in pickups up to somewhere around 1972.I just got my 54 Studebaker out of the shed,I'm going to use that a little this summer.It has the B.W.OD in it.I have it on the lift right now going through the brakes,with that free-wheeling you want to make sure both service and parking brakes are up to snuff.If you just leave it in gear when parked without the OD locked out the car will roll off.
 
i have 2 A"s w/bw-od. one kicks out when the clutch is engaged the other you must use a togglr switch [MUST be out of od to back up] i keep the one w/toggle controled od in franklin nc [mountains] i like that one better in the mountains, when in od and starting up a hill and motor needs help, just flip toggle and its out of od, then flip again for od if on a steep down grade while od is disengaged, pull out the cable to lock it out of od and it wont freewheel. OH, they are both 29's, the one in fl, has 4.11 gearsw/21'' tires,one in nc has 3.89 grs, had to take off the 21'' whls and put on 16'' to gear it down. tire size and gearing is important.
 
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