TI 85 overdrive not working, help!

[farmall1]

Hello Ford Lovers,
I have a 1970 F100 standard cab, long bed 2 wd with 390 and TI 85 3 seed with overdrive. These are factory equipment on this truck. The overdrive does not work (or I don't know how to use it) and I would really like to get it working. Does anyone know where I can find instructions on use and how to troubleshoot to find out what is needed? Many thanks in advance.

[hardlyrider]

I'm not sure how to post an illustration from a parts catalog, but that would be a good place to start for
understanding the components. Other than the transmission itself, there is a solenoid, governor, relay,
wiring harness, kickdown switch, and lock out cable. No-shift issues are almost always electric related.

As for operation, you should be aware that the overdrive shifts automatically when the cable in pushed in. While
the O/D can theoretically shift from any gear, it is very unlikely you would ever achieve the approximate 28 mph
(measured by the governor) required while still in first gear. So even though you could have six gears, it is only
practical that you will have four/five. The O/D shift occurs automatically after you reach the predetermined speed in
any gear by simply easing off the accelerator as you would do for a manual shift. The governor then tells the relay
to engage the solenoid and provide the shift. Depressing the pedal completely to the floor engages the kickdown
switch, breaking the circuit at the relay and allowing the solenoid to disengage the overdrive, thus downshifting
to direct drive. Pulling out on the overdrive cable locks out the O/D mechanically, rendering a conventional 3 speed
transmission, and preventing the transmission from freewheeling. While most manual transmission vehicles can be
"parked" with the shifter in any gear, greatest resistance is usually achieved in reverse or 1st (lowest) gear. However,
on the Warner O/D, the transmission freewheels in the forward gears and thus requires parking the vehicle in reverse,
unless the cable is pulled out, again mechanically locking the gears. This freewheeling feature also allows for manual
upshifts of the transmission without the use of the clutch and with no adverse effect on the transmission. This is
another feature that makes O/D equipped vehicles fun to drive.

The solenoid is about 3/4 the size of a soft drink can, located toward the rear of the transmission on the driver
side. The governor in on the opposite side just a little farther rearward. The relay is on the firewall to the driver side
of the engine. The kickdown switch is also mounted on the firewall directly behind the accelerator linkage. As
you move the linkage to full throttle, you should see the linkage at the firewall contact a six point round headed
plunger switch. One other note: There is a fuse holder located on the relay. Make sure the fuse is present and
not blown.

This should get you started. Once you determined that all components are present and you are comfortable with
the operation, post again and I'll try to help diagnose any problems. Parts are still available and with a truck that came
factory equipped with an O/D, I think it is well worth the effort to repair. Better fuel mileage, less wear on the motor,
fun to drive, and a great conversation piece. I once found all the components to install one in a '72.

[hardlyrider]

Here is a link to an article from a little while back. It explains it well:

http://www.fordification.com/tech/overdrive.htm

[farmall1]

Well, I will give an update on my efforts. I used the troubleshooting guide on this site. It was a great help. I had one wire cut and one in the wrong place. I also had a blown fuse. I was not able to get things to work. One day, at a cruise in a ran into a mechanic that I know that is about 70 years old and is a diehard Ford man. He said that he was familiar with the transmission. I took the truck to him and he said that it appears that the kickdown switch needs to be replaced. Do you know of a source for this? I have been trying to locate one but have been unsuccessful. Many thanks!

[TimCTaylor370]

I'm new to the forum and recently acquired an original '67 F100 equipped with factory od. You guys just paid the admission fee with this post. I didn't know how the od worked. Half auto half two speed.

[cep62]

Welcome to the site , there is a wealth of knowledge here.