What is a three speed overdirve manual transmission?

[The Big M]

My brother had a '77 Monarch with a 3-speed o/d manual (floor shift). That car had a 250 inline six. Also, I believe there are 3-speed overdrives that are similar to a 4-speed toploader. They're essentially a toploader case with a different gearset. No granny gear, with a 1:1 ratio in third and the overdrive as fourth.

I was researching this very subject recently in an effort to figure out what my brother's Monarch tranny was, and if it would fit a 223. It did fit a 302. I'm not sure if it was a toploader-style or not.

EDIT: Here's what I found before. It seems this is what my brother had, but I'm not sure it would be in a '74 van, unless it was swapped in afterwards:

http://www.5speeds.com/toploader.html

In passenger cars from 1977 to 1978 the Toploader was offered with an overdrive 4th gear. This was actually 3rd gear. They flipped the shift lever arm upside down so when you shifted into 4th you actually were in third gear place. A typical car that used this box was the Ford Granada. It looks identical to a regular toploader and that is why I mention it. You could actually take the gears from these boxes and retrofit early boxes to make a trick overdrive setup. These had a cast iron case. These were made partially by Tremac Corp. and were the start of the new Tremac coding of 170F series.

Ratio: 3.29 1st, 1.84 2nd, 1.00 3rd, .81 4th, and 3.29 Rev.

[turtle1056]

they were a terrible transmission toally unsuited for truck use - I have had four of them over the years

the synchros go out quickly, they tend to get a loud hum/howl to them, usually in Overdrive, and in one case under load it liked to pop out of gear goin down the highway

[ICEMAN6166]

pretty sure the 74 van had the cable operated od like the slicks.would be column shift too if it was original to the van.

[banjopicker66]

CAREFUL.

The term "3 speed overdrive" gets misapplied a lot.

An over drive is ANY gear ratio which has a driving gear turning slower than the driven gear. In other words, if the input ratio is 1, the output ratio is greater than 1. (Or put another way, when the output ratio is 1, the input is less than 1. An OD means fewer RPMs at the same speed.)

An electrically activated Borg Warner 3 speed OD was available in various types for cars and trucks from the early 1930's up to '72, when it was outlawed. It had an OD cable with a "T" handle to lock it out.
These ODs had an electrical solenoid, governor, relay and the like.
I think this is the type Iceman is referring to. It was banned after '72 because the freewheeling effect could easily make you lose control when going down a hill. (Don't ask me how I know this!)

After 1972, regular manual transmissions were offered with a 4th gear that was an OD ratio, rather than the usual 1:1 final gear output ratio. They weren't anything different than a manual transmission, except that the final ratio was an OD. No special electrics or unusual conditions to deal with, other than one would find in any other transmission swap.

Most OD ratios are .75:1 or thereabouts. That is, the crankshaft turns the input shaft three-quarters of a turn, and the OD gear bumps the driveshaft RPMs to 1, for a 25% decrease in RPMs.


Hope this clarifies the terms.

[61ford]

i bet what it is called a "imposer toploader" ive got one its a 3speed plus od so 4 speed check out this site see if it tells you anything

http://www.davidkeetoploaders.com/imposters.htm

[Greg D]

Doc, you have a 240/300-6 right? be a little bit more work to install (hydraulic clutch conversion) but just get a M5OD from a 92-96 F 150 (I found one at U-Pull-it for $85) and put in your truck if you want OD. It will get overall better mileage because of the closer ratios divided between 5 gears and have ALOT better drivability.

[fmartin_gila]

Doc,
Go to yahoo groups and find the Ford Truck 1900-1979 group. You may have to register to access the "files" section. In there you will find a downloadable manual that covers the BW 3+OD tranny. I have it downloaded and on my hard drive, if you can't access it. I can print up and mail you a copy if you want. Or you could pick it up next time through.
Fred

[6Slick5]

I have done some research for this also. I found this;

T170FT (Code-RTS)

Top loaded 4 speed with 4th being overdrive. Aluminum case and shift tower. Found in Ford F100-250 light duty trucks from 1984-85, also known as a TOD (top shift overdrive) Produced in 2 and 4 wheel drive versions.


at http://www.motivegear.com/tech_info/tranny_guide/tranny_guide.html

I found one at a local yard for $350.

I believe it is a basic bolt in for the 240 / 300 in our trucks.

Maybe next spring I will find another and actually make the swap.

Have Fun!
Marty

[banjopicker66]

As follow-up, I would NOT recommend anyone to get a Borg-Warner 3 speed OD - even free.

UNLESS you get everything, and I mean you either dissect the truck yourself, or you trust the person selling it to do so and do it correctly.

Rich trusted me when he bought mine, and I bet he can chime in with the difficulty of installation even with everything properly removed.

If you can get it all, it is probably a good thing. I only switched to a C-6 because of my hips.

You will need the following, not including the bellhousing and clutch:
Transmission (duh)
Working solenoid
Working governor
Wiring harness between solenoid, kickdown switch and governor to the relay.
Relay
Wiring harness between the relay, coil, ignition switch and kickdown switch
Kickdown switch with bracket (hard to find!)
OD Lockout cable and handle.

[Unibodyguy1]

Greg,
I'd sure like to find one of those 5 speeds for that amount of money here in Vegas, at Pick-A-Part they usually go for at least $400-500. Looks like I need to take a road trip to your neck of the woods to buy some cheap parts.

Michael