Overdrive Slip

Flex

Registered User
Hey guys,

I just drove the car out on the highway to see my buddy John from whom I bought it. She has been slipping in OD around town and from the search the boards it sounds like a bad range sensor or band shift solenoids.

It will be fine to 80 km/h or 50 mph and then it slips and the engine revs up. Anyone concur or have other input?
 
Have you checked the TV cable where it attaches to the throttle body? Sometimes the grommet cracks and the cable lets loose. That will cause that condition. Ford has several replacement grommets to fix that problem and I’ve been told there’s a brass one that doesn’t crack. Search around the board for that.
 
Have a brand new grommet in there. The odd thing is that it did the same thing evrey time. Works fine until that speed then slips.
 
Either way the overdrive band and/or direct clutches are shot. OD is the first to go. It's telling you it's on it's last leg.
Alan
 
Depending on how long your drove the car with the TV cable detached from the throttle body, not having the correct TV pressure on the AOD will make toast out of the tranny. Sounds like it's time for a rebuild, new tranny.. ect. I don't recommend getting one off the internet.
 
Last edited:
I never the drove the car at all without the TV cable attached. I installed a new grommet as I have 10 of them and just thought better safe than sorry.
 
From the start, I thought you were talking about the AOD-E because you mentioned a range sensor and solenoid. As you probably now know, the 91 model is an AOD which is entirely hydraulic. No electronics of any sort.

If O/D falls out after it warms up and then engages again (hunts), that could be due to wear in the valve body. If it slips (noticable shudder), thats probably a combination of band, clutch wear. As Alan noted, the direct clutch friction plates are probably worn out. Once they hit metal, the debris will cause other problems and it will get progressively worse. So looks like a rebuild is in your future.
 
It works fine until you pass that speed which is 80 kn/h 50 mph then its as though you put it in neutral. Just disengages until it gets back below that speed.
 
Flex,

What happens when you give it some gas in OD? If you floor it and the revs flare up, that is another clue that you have a slipping OD band. It is possible that the problem only seems to occur at a certain speed, but is really load-dependent. (I.E., the load required to drive 50mph is what sets it off.)

Alan, is it possible that he could have a torque converter problem instead of a friction problem? I.E., losing lockup?
 
Steve,

If I floor it from a stop and let it go until it hits 100 mph all is fine. If I gradually accelerate to the speed indicated, it always slips like it shifted into neutral at that speed. Once the car decelerates back below that speed, the transmission works fine again.
 
The transmission is ready to go. As has been said...Thsi is just a precurser to it.

There is no adjustment to be had that will fix this. OD band needs to be replaced
 
Well, the friend I bought the car off of has a rebuilt AOD with the bellhousing cracked he wants $50 for. If its toast, I could always weld up the fracture and run that one.
 
Back
Top