If you plan to install or upgrade the original AOD instead of the electronically controlled AOD-E/4R70W, you will have to pay close attention to the Throttle Valve (TV) control linkage.  The TV linkage or cable is used to tie the engine throttle to the throttle valve, located in the transmission valve body.  The hydraulic circuits in the valve body use both Throttle Pressure (from the TV Valve) and Governor Pressure (proportional to vehicle speed) as the sole inputs to control all transmission functions.  TV pressure is used to effect shift scheduling, but its most important purpose is to control transmission line pressure.  Proper line pressure is critical to transmission durability and shift feel.  It is important to adjust TV pressure properly and, for retrofit applications, TV linkage or cable fabrication must be completed correctly as part of the transmission installation.  Failure to set up the TV system properly will produce one "deep fried" AOD.  Owners of 1987 or later factory AOD vehicles should update the nylon TV cable bushing at the throttle body with the updated bronze part to protect their transmissions from the same fate.  For more information about TV adjustment and linkage or cable fabrication, please read the section concerning TV Linkage and Adjustment.
 

The seven-tooth speedometer geared rear-lube style output shaft is available from Baumann Engineering for pre-1988 AOD transmissions which lack this amenity. Use of this shaft is highly recommended for cars with numerically high (i.e. 3.55 or greater) rear axle ratios or those using the wide-ratio gear-set. Pre-1988 owners should also add the E8ZZ-7C063-A governor assembly (for about $20) to duplicate the effects of the now-obsolete Motorsport M-7060-A Rear Lube Kit. The E8ZZ-7C063-A high speed governor will allow you to raise your stock AOD shift points to those of an AOD-equipped 5.0L Mustang (about 4900 RPM WOT), if your AOD transmission is not from a 5.0L HO. The improved lube system is vital in preventing planetary gear failure due to inadequate lubrication (a highly unpleasant occurrence). This shaft is also useful for speedometer correction in 1990-93 Mustangs that were originally equipped with 2.73-1 gears. It is important to note that most Lincolns and some trucks use a 16-inch long output shaft (instead of the standard 15-inch unit) as well as a longer extension housing. Therefore, it is imperative that you specify the correct style of output shaft when ordering, or pay close attention to applications when bone-yard hunting.

While Baumann Engineering does not specifically manufacture an input shaft for the old AOD transmission, we do advocate the use of both the Precision Industries and Art Carr input shaft systems, depending upon application.

The Precision Industries input shaft is a replacement for the inner or direct input shaft, thereby eliminating shaft failure in high-torque applications, such as supercharged, stroked, or heavily modified engines. Another advantage of this shaft is that it may be installed without disassembling the transmission (once the transmission is removed from the vehicle). The Precision shaft also allows the use of a stock-style "lockup" torque converter.

The Art Carr system makes use of a solid input shaft and special torque converter. The solid input shaft replaces the two concentric shafts and eliminates the "lockup" feature of the AOD transmission. The torque converter uses a C-6 style input shaft spline which is only compatible with the Art Carr one-piece input shaft. The advantages of this configuration are its superior strength and the reduced engine RPM drop during the 2-3 shift. Disadvantages include less efficient operation, hotter operation and a loss of fuel mileage due to ever-present converter slippage, as well as a softer 2-3 shift and the need for transmission disassembly to install the press-fit input shaft. However, if you have a serious power plant which operates in the 400-plus horsepower range and you do not want to upgrade to an AOD-E or 4R70W, the Art Carr input shaft and converter will prove to be an indestructible ally. For more information, please see the Torque Converter Upgrades section of this document. The best way to avoid input shaft problems, of course, is to replace your outdated AOD with a state-of-the-art AOD-E/4R70W transmission.
 

AOD transmissions use one of three overdrive band servos ("A", "B" or "C"), depending on application. Earlier non-performance units are equipped with the smaller "C" servo. This letter designation is cast into the servo cover and piston for easy identification.

The "B" servo is a larger unit used in most post-1985 V-8 applications, all 351 applications, and High Output applications (i.e. Mustang G.T. 5.0 L, Lincoln LSC). This unit provides a 30% increase in band application force over the "C" servo.

The "A" servo is the largest overdrive servo available for the AOD transmission. This piece is used only with 1992 and 1993 trucks and the Thunderbird "Super Coupe" supercharged 3.8 Liter V-6. It will provide a 50% increase in band application force over the small "C" servo, and 16% over the "B" servo. If your vehicle already has the "B" servo, then the "A" servo will not drastically improve your 3-4 shifts, but if maximum overdrive band durability under harsh conditions and extra crisp overdrive shifts are desired, this servo is a must. To upgrade to a larger overdrive servo, the following parts must be ordered from your Ford dealer: