The best time to date is a...
The best time to date is a 12.80 at 103 mph. The drivetrain included a stock AOD transmission, Performance Automatic 10-inch non-lock-up converter, and 3.73 gears. The stock transmission let loose after a barrage of 12-second runs and over 180,000 miles of street use.
In 1980 Ford introduced its first automatic overdrive transmission, dubbed the AOD (automatic overdrive). The design wasn't entirely new, as it was based on its popular FMX passenger-car transmission. (If you're scratching your head upon reading FMX, don't feel bad-it's a small and insignificant transmission in the hot rod world.) Ford put the AOD in seemingly every passenger car and light truck, and it found its way into the Mustang from 1984 through 1993.
The AOD might have kicked off the overdrive era in Ford's passenger car history, but it was hardly considered a performance transmission-unlike today's highly praised and tough 5R55S five-speed auto. Ford built the AOD to withstand the lower output of the cars at the time of production.
The first step for Gerald...
The first step for Gerald Nusser of PA is to disassemble the transmission and inspect the parts.....
Back in the day, enthusiasts relying on the AOD transmission were faced with two options. First was to switch to a fortified C4, but as you know, it lacks overdrive, making it undesirable for the street crowd. The other option was to install a manual transmission.
Market demand for a tougher overdrive transmission grew in the mid-'90s. Aftermarket companies responded with modified versions, and one of the first companies on the list was Performance Automatic (PA). PA still offers two versions today-its Super Streeter and a Competition model. Both are a vast improvement over the stock slush-box, and this month we explore the internal upgrades of the Super Streeter.
....He begins by removing...
....He begins by removing the torque converter and the tailshaft cover (shown).
For the past six months or so, we've poked and prodded at a '93 Special Service Package 5.0L Mustang belonging to MM&FF staffer Marc Christ. The SSP coupe entered the MM&FF family with GT-40P heads, an E303 cam, and a Cobra intake, as well as exhaust upgrades and other small items. Today it features Edelbrock E-Street heads, Edelbrock roller rocker arms, BBK 255-lph fuel pump and adjustable fuel pressure regulator, and the same Cobra intake and exhaust upgrades. Those mods initially thrust the daily driver to a best of 13.12 at 106 mph at Bradenton Motorsport Park.
The addition of a PA torque converter dropped the coupe into the 12s with a best of 12.80 at 103 mph. The non-lockup torque converter was looser than stock (1,800 rpm versus 2,600 rpm), which accounted for the 0.3 drop in e.t.'s and also the 3-mph loss. As a side note, all quarter-mile runs were made with a short-belt and Mickey Thompson 275/40-17 ET Street Radials.
With the pan removed, Nusser...
With the pan removed, Nusser takes off the trans filter and unbolts the valvebody.
The daily driven status means this car has seen some serious roadway usage-the odometer is slightly north of 180,000 miles! The engine had been running like a champ, but the extra power smoked the original near-200,000-mile AOD transmission. Christ and the guys at MM&FF command central-now located in Tampa, Florida-yanked the transmission and shipped it to Gaithersburg, Maryland, home of Performance Automatic. The AOD received PA's Super Streeter treatment, which is designed to live comfortably up to 450 hp. If the power goes above that, PA will upgrade the AOD to its Competition model.
The team at PA tore down the transmission and after a thorough inspection, Gerald Nusser began the task of bringing the AOD back to life. After discarding the burnt parts, the next step was to clean all of the components to be reused in an industrial hot-tank. After everything was cleaned, the transformation into a Super Streeter AOD began.
Moving to the front of the...
Moving to the front of the transmission, Nusser pulls out the input shaft. "The stock input shaft is good to about 450 hp (flywheel)," comments Nusser. One of the biggest problems is not putting the shaft back in properly. As he points to here, there are wear marks on the shaft, and that is what should be slid back into the transmission. The metal becomes used to turning in one direction; when you change that direction, the shaft snaps even if you have just a few mods.
The rebuild comes with Alto heavy-duty clutches, an A/B servo, a PA Street/Strip valvebody, an Alto Red Eagle overdrive band, a new/upgraded drum and diode, and a new chrome pan with drain plug. The completed transmission was then put through its paces on a test stand. Every transmission that leaves PA is run on the transmission dyno to ensure it shifts properly, and doesn't leak or have any other problems. Because of the dyno testing, PA offers 12-month warranties on all of its street/strip transmissions.
The SSP coupe is now armed with firmer shifts and a stronger transmission for continued service on the dragstrip and on the street.
As Nusser digs deeper into...
As Nusser digs deeper into the case, we begin seeing some of the carnage. Here are the burnt clutches and scorched material that caused the transmission to slip.
It's common for the reverse...
It's common for the reverse drum snap ring to spread and come off, causing the intermediate sprag to become loose. A newly designed reverse drum and snap ring setup will be installed to prevent this from happening again.
The burnt clutches led to...
The burnt clutches led to a burnt direct hub-the scorching and burn marks are very obvious around the entire hub. The Super Streeter package includes a new hub.
The teeth are worn down and...
The teeth are worn down and missing on the Third gear direct drum.
PA installs a new Third gear...
PA installs a new Third gear direct drum, a stamped-steel piece, which is also an upgraded design in addition to the better material. Our old direct drum is in the background.
PA uses a mechanical diode...
PA uses a mechanical diode reverse drum. It was a service upgrade from Ford and is wider than the stock unit.
An Alto high-performance 2-inch...
An Alto high-performance 2-inch overdrive band replaces the stock 1.5-inch.....
....It allows for more holding...
....It allows for more holding power and grip.
The new reverse drum uses...
The new reverse drum uses a spiral ring and retainer to hold the diode in place. This prevents the snap ring failure that we showed earlier.
Nusser points out a hot spot...
Nusser points out a hot spot on the planetary. This was caused by the excessive mileage rather than overpowering it. The planetary is discarded as PA grabs another out of the parts bin.
Nusser uses a shorter sun...
Nusser uses a shorter sun gear (right) because of the thicker Alto overdrive band and larger reverse drum.
The Third gear direct drum...
The Third gear direct drum is filled with seven Alto high-performance clutches as opposed to just five.....
....It is the most Nusser...
....It is the most Nusser could fit in our drum. More clutches means more holding power.
As with the internals that...
As with the internals that are reused, the AOD case is cleaned in a hot tank.
The direct drum, ring gear,...
The direct drum, ring gear, and output shaft are reinstalled in the case.
The Low/Reverse band is replaced...
The Low/Reverse band is replaced with a stock replacement unit. According to Nusser, it barely wears out because the band isn't on for very long and doesn't see the power like other components in the transmission.
The sun gear follows the installation...
The sun gear follows the installation of the planetary gear set.
The trans case quickly fills...
The trans case quickly fills up with parts, and it is almost complete once the forward and reverse drum is installed.
A new bushing and seal for...
A new bushing and seal for the front pump are installed and lubed up.
The pump is the last piece...
The pump is the last piece to the internals of the AOD transmission. It slides in and Nusser bolts it down.
These little parts make up...
These little parts make up the rest of the transmission. Seen here are the different springs and plungers for the valvebody, input shaft, governor, various bolts, and the speedometer gear.
Nusser rebuilt the governor...
Nusser rebuilt the governor because it was sticking when he manually operated it. There was dirt and grease clogging up the internal parts. He disassembled it and used brake cleaner to cleanse it. The governor controls the shift timing and shift points.
A PA valvebody is installed...
A PA valvebody is installed to provide firmer and more positive shifts. Contrary to belief, the valvebody doesn't control the shift point. That is accomplished through TV cable adjustments. Once the TV cable has its base location, you can adjust it to shift higher or lower from there.
The transmission filter is...
The transmission filter is bolted to the valvebody and the trans gasket is laid into place.
The case is painted black;...
The case is painted black; inside the bell housing is painted gray. Once the paint dries, Nusser runs the transmission on the test stand to ensure it operates properly.