3sp O/D question

[ezernut9mm]

is it possible for the o/d to be "stuck" on? i read that the o/d wouldn't engage under 27 mph, but it really seems that my car is stuck in o/d. it has a 3.89 rear and it is like taking off in second gear from a stop. also, it is only turning 2250 rpm at about 65 mph. engaging or disengaging the o/d with the lever had no effect other than to cause a freewheeling effect on decel when the o/d is engaged. how can i diagnose the o/d unit? thanks for any help.

[slick4x4]

You could tell by jacking up a back wheel
Put a mark on your driveshaft
Put your trans in third
Turn your engine over by hand exactly one revolution
Check your mark on driveshaft
If it has turned any more than one turn
Your OD is on

[ezernut9mm]

oh, i know it's on. there's no way i'm pullin' 2250 at 65 mph with 3.89 gears. plus it takes off like it's in second. i just want to figure out how to fix it. i have lots of different sized hammers. it's just knowin' where to hit it.

[slick4x4]

I have no experience with an OD whatsoever....
But I did find this ... http://www.fordbarn.com/forum/showthrea ... &showall=1
Sounds similar to yours ....
Grounding of the governor might be a culprit

[fmartin_gila]

Chris,

Over at the Fordification, I think under the Technical part, there is or was a reprint of the original Overdrive Manual. There is also some good info on the "Old Burb" site, even though that site is for Suburban guys.

Fred

[bruceandersson]

You always should be able to use the cable to dis-engage the OD and over-ride what ever the solenoid and speed sensor are doing. You could have a couple of problems. I'd start by disconnecting the power. This should also take it to non-overdrive mode. This will tell you if it is a mechanical or an electrical problem. If it stays in OD, then I'd suspect the solenoid or the internals need freeing up. If it is now out of OD, then I'd suspect your speed sensor/governor is stuck. The way they are supposed to work is that the governor is normally closed until you reach a certain speed in which case it opens the circuit and send power to the solenoid. It closes again when you drop below another set speed. Seems to me the speeds are something like 40-45 initially and 27 when slowing. You still don't shift into OD until you let off on the gas a bit. Hope this helps.

[ezernut9mm]

thanks for the links fred and pat. some good reading there. bruce, when i got the car all of the o/d electrical stuff was unhooked and it was still in o/d. so i am suspecting it's mechanical. man, i wish i had a lift.

[bruceandersson]

If the cable is missing, you should be able to tie off the lever it should have been run to. Since there is no electric, it should be in normal mode by default, so I think you're right - something is stuck. You could also remove the solenoid to make sure it is moving freely - that's what I suspect must be stuck.

[ezernut9mm]

everything is present and hooked up. i think something is either stuck or there is an electrical short. my kingdom for a warm shop with a lift!