VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc Some questions about the 3 speed o/d trans

I have a project idea running around in my brain that one of those trans would work great in so I have some questions,I presume they were first intorduced around 55 and just how long were they produced. Did any have a syncronized first gear and did they all have a freewheeling effect when o/d was engaged,I have never owned a vehicle that one was installed and never driven a vehicle with one in it so I know nothing about them. The project I am thinking about is a 46-8 coupe with a 235/261 hooked to a 3 speed o/d trans and 55-7 rear end done up as a late 40s mild custom that will be able to cruise 70 down the highway so I can drive it to Florida,I do not want to go with a T-5 on this one as I want to keep the shifter on the column and look period correct.

I had a '56 Chevy with overdrive three speed many years ago. It was manual shift with electric selenoid for overdrive. Yes it had free wheeling when in overdrive. No syncro in first gear. If you can find an three speed overdrive from '66 or newer it would have the syncro first gear. Either tranmission should bolt up to the 40s six. Will need 12v for overdrive and cable to engage or disengage.

Steve at the Filling Station has a '31 Coupe with an overdrive I think is a BW and came from a Studebaker. He could tell you for sure.

Just what is freewheeling,I have heard about it but like I said never used one of those trans before.

The freewheeling is what allows the transmission to be shifted without using the clutch.

I know how to shift without the clutch with a regular trans so is this better?

The BW (Borg-Warner) overdrive transmission gives you a 30 percent gear reduction. At 70 mph the engine is doing the equivalent of 49mph. It save on rpm's and also improves your gas mileage.
The freewheeling aspect means that if you take your foot off the gas it is like being in neutral, you get no engine braking. You will find yourself using the brake petal more to slow down.
I have the BW unit in my '50 Plymouth. I went from 13/15 mpg to 21 mpg and the engine never labors.

Does the freewheeling only come in when o/d is engaged or does it happen all the time,I know nothing about those trans and need to know before jumping in with one.

there is no freewheeling when the OD is locked out.
One other advantage of O.D. is the factory equipped cars used a lower rear axle ratio. A 1955-1969 with OD had a 4.11 ratio where as the regular 3 speeds had like a 3.70 or 3.55 (with 14 " wheels.)
The 1955 Chevrolet literature states 22 % fewer engines revolutions ( compared to the 3.70 ratio)
Most makes advertisd a 10 to 20% increase in gas mileage.

What year was it last offered in a car or truck.

My second attempt for a reply, first reply was somehow erased, lost, I think.

I recently purchased a 1951 Chevy from the estate of my late friend. A very detailed display of mechanical update. From all outward appearances, the vehicle looks factory correct, period correct, as you stated.

First, vehicle was converted to 12 volts.

He utilized a 1961 235 engine, a 1959 6 cylinder bell housing, a 1959 6 cylinder 3 speed with O.D., with a 9" Ford 3:50 ratio positraction rear axle assembly, in the event a V8 was ever in the future.

Transmission cross member was supplied by Walton MFG.

Shifting is still done through the factory column, BUT much time was spent in reshaping and aligning shift rods, from column to transmission. Clutch linkage was NOT modified from the 1951 configuration.

O.D. engagement is done with the 1959 factory "T Handle", which is mounted under the dash, as it was in 1959. Solenoid engagement is now done through a toggle switch, instead of a carb mounted switch.

My friend finished this project, then enjoyed his accomplishments for 229 miles, before passing from Cancer.

I have only driven this car a total of 40 miles. I had knee replacement surgery (clutch knee) and have not been able (yet) to handle a clutch pedal.

I do have a few pics of the undercarriage, must say the underside is as pristine as the top side.

I would need an email address, if you have any interest in the pics.

P.S. I do have a 1955 Chevy rear end, brake drum to brake drum, as well. It has been in heated and cooled storage, in my basement, for I was going to do a open drive line conversion on my other '51, the one in the Avatar, but then declined to do so.

Bobg,

Very interesting post about the drivetrain on the 51 you've acquired. In the 40 miles you have put on it, how did you like it in regard to the drivetrain and overdrive?

I'm very interested in this thread because this is the same drivetrain that I would like to install in my next build- a 41 Chevy Cabriolet

Finding a decent trans might be harder then finding the 46-8 coupe.

Driving it only 40 miles was not a fair test. I was watching gauges, getting accustomed to shifting, steering. Determining if I was in or out of overdrive, etc.

Recall, my friend had already passed, so I was on my own. No one to ask about this or that, but I did have all his notes and receipts. Show and tell always works better.

With the 235, which is bored to 246, I have to say the Ford 3:50 rear could have or should have been a 3:70 or 3:90.

I'm in foothills of Appalachian Mountains .... maybe the 3:50 would have been fine for flat, level terrain.

I received your PM, will send you what undercarriage pics that I have.

Please note the pic quality is not the best.

I have a 9 inch center section with 3.70 gears that I would trade for those 3.50 gears but you are a little too far away.

Richard,

Pics have been sent to your email address.

Bob.

My kids live in Mentor, Ohio, just east of Cleveland.

I make the trip from Georgia to Ohio, several times per year, going past Dayton on I 71.

I also have a complete "spare" 1959 6 cylinder, 3 speed overdrive tranny.

I look forward to more updates once the knee heals. Thanks for the pics.

You're welcome for the pics.

If the knee will not handle the clutch chores, a turbo 350 will do the work for me.

If the knee will not handle the clutch chores, a turbo 350 will do the work for me. [/quote]

Say it aint so

Say it aint so [/quote]

A man's gotta do what a man's gotta do. Time will tell.

With the present knee scenario, I'm pretty certain the Atlanta Falcons will not be drafting me to do their field goal chores.