Ford AOD - Automatic Transmission
1. The pre-88 AOD should not be used for serious HiPo or Drag race use. The lubrication system is not up to the job (the output shaft is the main concern). 88 and later is a better choice and in many cases an 88+ output shaft can be installed in an older AOD to upgrade.
2. The number one cause of failure in a stock or racing transmission is heat. Installing a quality aux. fluid cooler after the in-radiator cooler is a good idea and a must if you have a high-stall converter. Also use the fluid recommended by the overhaul kit’s manufacture. Ford Mercon (or Dextron III) is normally used in all AOD’s. Ford now recommends MerconV for the AOD/4R70W.
3. All AOD’s have the same small block bell housing bolt pattern as well as the 11-½” converter bolt circle. Normally engines with a C4/C5 11-½” bolt circle flex plates can bolt to the AOD.
4. You may find a yellow plastic plug with an o-ring around it in the pan. It’s a shipping plug that was pushed into the pan when installing the dip-stick tube at the factory. Pitch it.
5. You should tear down your AOD and inspect before buying any parts. It may already have upgraded parts or damaged parts that you may not be aware of which will dictate what overhaul kit and extra parts to get.
6. If you have trouble getting the bell housing flush with the engine block during installation or can’t turn the flywheel after bolting up, the converter may not be all the way in the pump. The converter must engage the two input shafts, stator support and pump gear lugs. With the converter installed properly, the converter hub will be deeper than the straight edge surface of the bell housing. With the transmission bolted tight to the block, you should be able to wiggle the converter stud easily in the flywheel. Note; If the engine has been changed or a stick shift to automatic swap is preformed, be sure the pilot bearing is removed from the rear of crankshaft.
7. 89 and later AOD’s don’t have a 3-4 accumulator in the case (a few 5.8L trucks may be an exception). The valve bodies are different on those models so be careful when swapping VB’s between pre and post 89 trannies. In other words an 89+ VB could be used in any AOD but an 88 or earlier VB most have a 3-4 accumulator installed in whatever year case your working on.
8. Setting the TV (throttle pressure) cable is a crucial adjustment for the AOD but it’s not hard to do. Normally the cable is set so there’s neither slack or has tension on it in the closed throttle position. With the throttle pushed to wide open, there should be just a little extra movement left in the linkage on the tranny.
9. Though normal hand tools and a few tools that can be fabricated is needed to repair the AOD, installing the clutch pistons without the special seal protectors is almost impossible. You’ll need to beg, borrow or steal them to repair this trans.
10. AOD’s come in two output shaft lengths. Most vans, MarkVII’s and some Town Cars use the long shaft (extension housing is about 11 inches long). Mustangs, Tbirds and most F series trucks use the short shaft (extension housing is about 10 inches long).
11. If you need to make a custom length dipstick and tube, remember that the normal warm in park fluid lever is even with the case’s oil pan gasket rail. The center of the dipstick’s full mark crosshatch will be level at the pan rail surface.
1. The pre-88 AOD should not be used for serious HiPo or Drag race use. The lubrication system is not up to the job (the output shaft is the main concern). 88 and later is a better choice and in many cases an 88+ output shaft can be installed in an older AOD to upgrade.
2. The number one cause of failure in a stock or racing transmission is heat. Installing a quality aux. fluid cooler after the in-radiator cooler is a good idea and a must if you have a high-stall converter. Also use the fluid recommended by the overhaul kit’s manufacture. Ford Mercon (or Dextron III) is normally used in all AOD’s. Ford now recommends MerconV for the AOD/4R70W.
3. All AOD’s have the same small block bell housing bolt pattern as well as the 11-½” converter bolt circle. Normally engines with a C4/C5 11-½” bolt circle flex plates can bolt to the AOD.
4. You may find a yellow plastic plug with an o-ring around it in the pan. It’s a shipping plug that was pushed into the pan when installing the dip-stick tube at the factory. Pitch it.
5. You should tear down your AOD and inspect before buying any parts. It may already have upgraded parts or damaged parts that you may not be aware of which will dictate what overhaul kit and extra parts to get.
6. If you have trouble getting the bell housing flush with the engine block during installation or can’t turn the flywheel after bolting up, the converter may not be all the way in the pump. The converter must engage the two input shafts, stator support and pump gear lugs. With the converter installed properly, the converter hub will be deeper than the straight edge surface of the bell housing. With the transmission bolted tight to the block, you should be able to wiggle the converter stud easily in the flywheel. Note; If the engine has been changed or a stick shift to automatic swap is preformed, be sure the pilot bearing is removed from the rear of crankshaft.
7. 89 and later AOD’s don’t have a 3-4 accumulator in the case (a few 5.8L trucks may be an exception). The valve bodies are different on those models so be careful when swapping VB’s between pre and post 89 trannies. In other words an 89+ VB could be used in any AOD but an 88 or earlier VB most have a 3-4 accumulator installed in whatever year case your working on.
8. Setting the TV (throttle pressure) cable is a crucial adjustment for the AOD but it’s not hard to do. Normally the cable is set so there’s neither slack or has tension on it in the closed throttle position. With the throttle pushed to wide open, there should be just a little extra movement left in the linkage on the tranny.
9. Though normal hand tools and a few tools that can be fabricated is needed to repair the AOD, installing the clutch pistons without the special seal protectors is almost impossible. You’ll need to beg, borrow or steal them to repair this trans.
10. AOD’s come in two output shaft lengths. Most vans, MarkVII’s and some Town Cars use the long shaft (extension housing is about 11 inches long). Mustangs, Tbirds and most F series trucks use the short shaft (extension housing is about 10 inches long).
11. If you need to make a custom length dipstick and tube, remember that the normal warm in park fluid lever is even with the case’s oil pan gasket rail. The center of the dipstick’s full mark crosshatch will be level at the pan rail surface.