I have an AOD that just started slipping while in overdrive (I accelerate and there is nothing there), if I pull it down in drive and it shifts fine. I checked the fluid and it's ok. The transmission is in my T-Bird which is my daily driver which has 153k on it. What do guys think it could be? I wonder if it is one of the clutch packs? How long do think I can drive it in drive vs. overdrive without it going out on me? I would hope it would last until warmer weather arrives then I can afford to stop driving it, park it and then pull it, and then drive one of the Mavericks. I hate the thought of putting one of the Mavericks on the salted roads. Thanks in advance for your help!
Dave, It sounds like a problem I had awhile back on my '87 Ford LTD Crown Victoria! Apparently the rubber (vacuum?) hose to the modulator on the transmission developed a crack and was not supplying vacuum to lockup the Overdrive in the tranny!. Slide underneath and check that hose! As far as driving around in "D" instead of "OD", don't worry about it at all. It basically acts like a 3-speed and revs the engine a bit higher, but no other problem than that at highway speed. Tracy
Well it's not the vacuum line, it looks like the clutch. Looks like I can drive it for a while until warmer weather comes along. I have done some 3 speeds before, but the AOD is new to me. Has anyone tore down an AOD down before? Just want to get some general ideas what I am getting into? Thanks.
the AOD does not have a vacuum modulator. It uses a TV cable or rod (depending on year, application) to regulate internal pressure based on throttle input. If yours does not have OD, I would suspect that the OD band is toast. I've had a couple of them apart, they are not real hard, but you must be familiar with the internal workings of automatic trannies. We picked up a overhaul manual I think at autozone that covers the C3-4-5, C6, and the AOD. Also, if you are considering rebuilding it, IMHO, it would be wise to upgrade to the larger OD apply servo and the wider OD band (from F150 trucks and T-Bird SC's.) Also a good improvement for the AOD is the lower gearset for the E4OD automatics, which changes the first gear ratio from the stock 2.48 to 2.84, which makes first and second gear acceleration a bit better. Supposedly, the newer gearsets are stronger as well, but they are not a requirement. Weak links in AOD's are the OD band, OD apply servo (usually too small for V8 applications), and the input shaft, which is extremely long and small in diameter. Good luck
Thanks for the advice on the upgrades. I am currently taking an auto drivetrain class that is now focusing on automatics at a local college so I guess I know what my first project is going to be.
You have an OD band that has worn down. If you are concerned about performance, consider replacing the overdrive servo with a unit out of an early 90 Lincoln Mark series. The one you have will be stamped 'C'. The one from a Lincoln is a 'B' and clamps the band 30% tighter. There is also an A servo if you wanted to go that far. Then there are other mods that can be done. The 2 to 3 shift pressure is cut back 30% by design and is easy to fix at the valve body. Your ready to rebuild at any rate.
