hi folks, I have just discovered this forum, so perhaps you all can answer a question for me. My 1970 f100 4x4 has instructions in the owners manual for an optional overdrive. All I know is it was operated by a T-handle under the dash. I would guess it was only offered on 2x's but I'd still like one.Are they available? Anyone got one, and if so is it worth having?

 

[updated:LAST EDITED ON 10-Aug-02 AT 01:26 AM (EST)]Martin: The overdrive (OD) transmission you speak of is the Warner T-85N transmission, and yes, it used a T-handle, but that was to lock it out. Let me explain the old OD concept. It was not what is today called an OD, but the end result was the same, with a higher final gear ratio. The old ones used what you could call a second transmission or second gear box added onto the back of the main transmission. It had a sun and planetary gear arrangment. A pawl, activated by a large electric solenoid, would engage the OD and lock it in. A governor activated the solenoid at speeds of about 30 mph. In mine, I get up to about 29 mph, let off the gas, and then hear a "clunk" as the solenoid pushes the pawl home, and engages the OD.
When not in OD, though, the transmission, even though it is a manual, will not lock, but it will freewheel. On other words, if the driveshaft speed exceeds that of the engine speed, you roll, whether parked or running downhill. (The exception is Reverse. You ALWAYS leave the truck parked in reverse.) The T-handle lockout was to prevent that, but then you didn't get to use the OD and get better mileage. I had situation once where the OD fuse blew as I was going down a 6% grade with about 1500 pounds of stuff. That was pretty scary, when the solenoid popped out and I lost the ability to use my engine as a brake assist.
I need to replace the cab on my '66 because my dad borrowed the truck, left it in gear, but not in REVERSE, and it rolled backwards downhill. The door was open and caught a tree, which bent the cab door frame back a bit.

Having said all that, I really like it. I have a 352 2V, and get nearly 18 MPG on the highway at 70 mph, with a 3.00 rearend ratio. Not much power, but good mileage. Really really poor in town, though, but that's to be expected. Not anything abnormal.

The T-85N was used in all makes and models of vehicles, all brands. Warner just did up the wiring to match the customer's (eg, Ford, Studebaker, AMC, Nash, GM, etc) wiring. Even so, they are not often found anymore, especially the R-11 OD casting, which was the heavy duty application. The R-10 can be found, but it is not suitable for a truck, and they are really only marginal for a heavy car, IMHO.

Check out this link (not my own!) about a guy who put one in his Suburban. Excellent pictures and detail.
http://www.classictruckshop.com/clubs/earlyburbs/projects/over/drive.htm

One final thought. I am considering converting my truck to an automatic due to the arthritis in my hips. If I do so, it won't be for at least 6 months, but I will remove everything for someone else to install as a complete package. It will include bellhousing, clutch, linkages, wiring harnesses, two piece driveshaft, everything. Let me know if you are interested.

 

Thanks for the great reply.You answered a lot of questions for me. I will look for the parts I need up here, but perhaps in 6 mths I can chat with you again if I have no luck. One other question tho, is this the same trans as I see called a three speed o/d quite often? Thanks again for your help.

 

Martin: Sorry for the delayed response; I'm traveling, and don't have daily access to a computer.
To answer your questions about the OD transmission, there were MANY variations of the OD tranny made from shortly after the war to about '72. There are Saginaw, Studebaker, Warner, Ford and more. Ford quit making their own overdrive about 1960/61, I think, and went with the Warner application.
All of these have different bolt pattterns, so you need to find one which will bolt to YOUR bellhousing, or a different bellhousing that will bolt to your engine. Or proposed engine!
For your truck, I HIGHLY recommend you get the Warner T-85N since that is what Ford used in their trucks from about 62 on.
The T-85N differs from Warner's standard 3 speed T-85 in that there are extra casting holes for the OD shift rail,in the length and type of output shaft, and the input shaft as well. In other words, you cannot easily use a standard T-85 tranny and simply bolt on the OD housing.
There are Warner T-85N 3 speeds out there, but they are getting harder to find, even on E-bay. I search there regularly. Most of the ODs are not Warner, and those that are have the R-10 OD housing, which is the light duty version. I have seen several Warners with R-11 housings, but they did not have Ford bolt patterns.
Good luck with your search!

 

banjopicker, in if martin is not interested in you tranny when you get around to taking it off I might be. Just shot me an email.
Jeremy

 

john , Will the t85n\r10 fit or boltup to my 77 f250 , np435 , and will it handle the torque of a 400 with a mild cam?????I got the impression that it would boltup to alot of different ford bell housings.........thanks , fd

 

[updated:LAST EDITED ON 14-Aug-02 AT 11:41 AM (EST)]Fatdaddy: I wish I could answer your question about the bolt pattern with certainty, but I can't. I would guess probably not.
Additionally, I wouldn't recommend the R-10 OD for a truck. It just isn't strong enough, IMHO.
As I was researching the rebuild on mine, I received this info from a company out in OR. Perhaps they can be more specific in the information you seek. I hope this helps.

A remanufactured T85 3spd would run you $760.00 exchange, the 3spd w/OD would run you $852.00 exchange. I do also have a kit available for the T85. This would be a K85 kit (includes bearings, seals, gaskets). Your cost on that would be $81.59 + S/H (add $2 if you have OD for the extra seal). We accept paypal, visa/MC/Disc/Amex (call Spencer @ 800-776-1191), money orders, checks, cash (at your own risk). Thanks,

Spencer Hodes
Transmission Exchange Co.
1803 NE ML King Blvd.
Portland, OR 97212
800-776-1191

txchangespencer at earthlink.net

 

John , thanks for taking the time to reply to my question..........What I am comparing here is the cost of the t85n w\r11 hd overdrive (if it will work on my 77 f250\400 bell housing) vs the gearvendors od unit which will run around 3,000 by the time i get it installed and a new driveshaft built to fit in the interim betwixt the od unit and the np205 , divoraced xfer case.....It looks that the gearvendors unit is going to be best investment , overall even though it is a tad more out of pocket---thanks for your help!!! , fd

 

I would agree with you! Mostly because the T-85N, although a good tranny, has so many obsolete parts that it is probably worth the Gearvendors OD to use it. I didn't mention the OD relay, kickdown switch, or governor (which usually come with the tranny, but often are bad). Also, the wiring harness isn't diffcult to construct, but it can be very complicated.
If I had the choice, I would go with Gearvendors. But then, if money is the biggest issue, and I could get the COMPLETE package, I'd make the T-85N my second choice. But ONLY if I can get the complete package, which is why, if I do switch to an auto, I'll sell it that way, and not piecemeal it out.