T85 Over drive

Disconnect the governor at the transmission and connect a test light between the governor and and the battery + terminal (or battery - if positive ground system) Drive the car between 26 to 30 mph; the test light should light up. Slow down below about 23 to 21 mph; the test light should go out. You can also do this with the rear wheels off the ground. If you have the governor off the trans you can clamp it (very gently!) in a vise and connect a VOM to it set for continuity. Chuck the shaft in a drill and spin it up, doesn't matter which way. If the contacts are closing you'll see it on the VOM.
 
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Do you suspect the governor isn't working? They rarely give trouble. What can happen is the speedometer drive gear on the OD output shaft can move so that the governor driven gear is no longer meshed with it. I had that problem on my Merc. Had to pull the governor and pry the gear forward a bit to get it to mesh. For some reason the speedometer still worked, probably because its driven gear is a bit more toward the rear of the shaft. I've heard T85's are somewhat notorious for this. The speedo drive gear is held in place by a ball beairng that sits in an indentation in the shaft; the drive gear snaps over it. I lost most of my hair before I sussed the problem.
 
On my first trip out the speedometer read 100 mph thru town, when I got in back on rack the speedometer gear looked like it was not meshing and I replace with another speedometer gear. I can't tell if the overdrive is working. The car does free wheel, but I don't think the rpm's are dropping when it goes into overdrive. installing a tach this week.
 
When you reach the OD cut-in speed, usually 27 to 30 mph, listen for a snap from underneath the car indicating the solenoid is energized. When you lift off the gas it should complete the shift, you will feel a slight lurch as the shift completes. If it freewheels when you let off the gas above the cut-in speed it is not going into OD. It's usually an electrical problem between the governor and solenoid, or the solenoid itself. You can test the solenoid by connecting a long wire from the battery to the solenoid terminal on the relay. When you touch the wire to the terminal you should hear the solenoid click. If it doesn't the wire from the relay to the solenoid is open or the solenoid is toast. Also check that the OD shift lever has full travel in both directions when you push/pull the cable.
 
Tomjc said:
I have it in a 54 Ford ranchwagon with a 292 and 12 volt negative ground system
Click to expand...

I do love station wagons and you will love the T85 overdrive when it is up and running properly........Dobbie Gillis is right on with his advice....
The electrical part of the overdrive is what has to be thoroughly understood...it sounds more complicated than it is....read everything that there is about the "electrical" part of the overdrive T85 + T 86 trannys....there are many good schematics on this that show exactly how the current flows thru each part and in what order, so it will becomes clearer on how to test what is working properly.
I am waiting for my overdrive harness to come in tomorrow and will be hooking up the electrical in my T86 in my 55 Ford.....will keep you posted...J in CT

P.S.....in the three T85-86 O/D trannys I have installed. I have found that most problems end up being loose connections or a bad solenoid. There are two sets of points in these solenoids and "both " have to be in good working order.
 
Thanks for all your input. I removed the governor and it would not go to ground when I hooked a drill to it. (New one on the way) I copied the schematic from the old car manual and notice the wire on the governor in the schematic is hooked to a switch on the back of the trans before it goes to the switch under the gas pedal. what is that all about, I don't have that switch, I only have the switch under the gas pedal.
 
The diagram is for 1950 and earlier models. The switch was there to disable the OD if someone shifted into reverse with the cable pushed in (OD enabled) since the planetaries won't transmit reverse drive. The switch was deleted after 1950 on Ford products and probably most other makes. It's not needed because there's a shift rail inside the trans that moves the planetaries out of engagement with the sun gear when reverse is selected. BTW, when you get it working be sure that if you park the car with the cable pushed in that you put the shift lever in reverse to prevent possible roll away. The engine is not connected to the rear axle when parked with OD enabled. Alternatively, you can lock the OD out by pulling the cable out and/or setting the parking brake. DO NOT pull the cable out while moving unless you do it while the trans is kicked down to direct drive by tripping the kickdown switch under the gas pedal.
 
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