1985 Ford LTD AOD Transmission Question/Problem

Hello Everyone -
I have a 1985 Ford LTD with (I am almost positive) an AOD Transmission. I looked at the Haynes Ford Transmission Manual and made
this determination visually and by the sticker.
Anyways, This vehicle has 117,000 miles on it and my transmission will not go into overdrive. I have Reverse, and my low gear without a problem. On "D" I make it up to 35 MPH but the engine is reving extremely high. I've looked at the books, webpages, and I cannot make heads or tails out of it.
If you need additional information, I will try to help but anything at this point would be appreciated.
Also, I am in the military, so I have access to a full auto shop that I can do anything I want with the vehicle, how long does a rebuild generally take? (I am comfortable doing to work, but I am lousy doing diagnostics)
Thank You Robert
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On Fri, 14 Mar 2008 17:39:35 -0700 (PDT), Wuk

The most common problem with those symptoms is a bad overdrive band. This require teardown of the trans to repair. The biggest things you need as far as tools is a universal clutch pack compressor common to most rear drive domestic cars, a good assortment of snapring pliers and the seal protector set for installing the clutch pistons. The clutch pack compressor will probably set you back around $100 if the shop does not have it. The seal protector kit around $40 for the plastic ones. You can go for broke with the machined metal if you intend to do this frequently. Before you pull it, be sure to check the throttle cable bushing at the carb. The originals were plastic. The replacements are brass. Should cost under $5 even from Ford. If this bushing is bad, it can give the symptoms you describe. If it has been this way long, replacing the bushing may not be the cure. The throttle cable controls the trans line pressure and is sensitive to adjustments - big time. If the bushing has been loose long, the pressure has been low allowing the trans to slip. The clutches are probably toast if this is the case. BTW, you will need either a trans jack which can usually be rented or a couple of buddies to get it out and back in. When you reinstall the trans, make damn sure the converter is fully seated in the trans. You should be able to rock the converter back and forth with your fingers after the trans is bolted to the engine and before the converter nuts or bolts are tightened. If you can't pull it back and reseat the converter. If the converter is not seated, it will destroy the engine thrust bearings and the trans pump in short order.
Lugnut
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Is this the big LTD Crown Victoria or the smaller LTD that was the same size as the Fairmont? Both were rear wheel drive cars, but it would help to know which model you're talking about.
I'm not a Ford expert by any means, but I thought rear wheel drive Fords had vacuum modulators that regulated the shifting in their automatic transmissions. If the modulator isn't working, or if for some reason the engine is out of tune, causing a poor vacuum signal, the transmission will shift late, causing the engine to rev before upshifting. I assume you mean it's in 2nd gear before upshifting into 3rd at 35 mph. With overdrive, the 4th gear doesn't usually kick in until 45 mph or so even with light pressure on the gas.
Are you sure this has an overdrive transmission? I think the Crown Victoria had it by 85, but I don't think the smaller LTD did... GM cars had a D with a circle around it if the car had an overdrive transmission, then D or 3, then 2, and then 1. I'm not sure how Fords were during this time period, but if it's a regular D, then 2, then 1, I don't think it has overdrive- it would be a regular 3 speed automatic- which is what I think the smaller LTD had. Someone correct me if I'm wrong.
In any case, I DON'T think you need to do a rebuild. Why not change the fluid and filter and check the vacuum modulator (or throttle valve cable adjustment if that's how shifting is controlled)? The service manual will tell you how to do it.

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A friend's '89 mustang as well as a '92 Tbird sport I owned both had this problem.
Both had the 302 V8 with the overdrive automatic.
It turned out to be a 5 cent part...a plactic bit attaching a throttle position cable that goes from the the EFI throttle (attachs next to the throttle cable if I recall correctly) down to the transmission.
Someone told me that this cable controls the oil pressure in the trans, too. This makes sense, since my trans fluid ended up turning black.
--Ken
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Ken R. Dye an optimist is a guy |
Chicago, Illinois that has never had |
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