Ford AOD transmission

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AOD
ManufacturerFord Motor Company
Also calledAODE
AOD-EW/4R70W
Production1980–present
PredecessorCruise-O-Matic
C-5
Successor6R
Class4-speed longitudinal automatic transmission
RelatedE4OD
ManualsService Manual

The AOD (for automatic overdrive) was a four-speed automatic transmission with overdrive. Introduced in 1980, it was Ford's first four-speed automatic overdrive transmission. The design is based on the same gearset as the Ford FMX transmission of the 1960s and 1970s. The AOD replaced the majority of Ford's older transmissions, including the Cruise-O-Matic and C5.

Applications:

Gear ratios

  • First: 2.40:1
  • Second: 1.47:1
  • Third: 1.00:1
  • Overdrive: 0.67:1
  • Reverse: 2.00:1

AODE

The AOD was redesigned with electronic controls in 1991, becoming the AODE. It was mainly intended for the new Modular V8 at first, but it was also adapted to the old AOD bell-housing for vehicles still powered by OHV engines. While the AOD and AODE/4r70w share some basic components like oil pans, gear sets (AODs and AODE can be retrofit with 4r70w gear sets), most of the internals are not interchangeable. The transmissions are not interchangeable either, as the AOD only uses a throttle valve cable for operation. The AODE and 4r70w are controlled by the Powertrain Control Module (PCM) also sometimes referred to as the Electronic Engine Control (EEC).

Applications:

4R70W

A revised version of the AODE was released in 1993 with the Lincoln Mark VIII. 4R70W stands for 4 gears, Rearwheeldrive, 70 number assigned by Ford which represents the input torque in Lb-Ft for which the transmission was designed times 10 (70 x 10 = 700 Lb-Ft) and Wide gear ratio. It has lower 1st and 2nd gear ratios for better take-off acceleration and improved gearset strength. On vehicles powered by a 5.4 L V8, a stronger gearset is used than in normal duty 4R70Ws. In 1998, due to durability concerns, the intermediate one-way roller clutch was replaced with a mechanical diode providing extra holding capacity and longer service.

The gear ratios are: 1st: 2.84 :1 2nd: 1.55 :1 3rd: 1.00 :1 4th: 0.70 :1 Rev: 2.23 :1

Applications:

Many improvements have been made to the 4R70W since 1993, the most significant was the use of a "Mechanical Diode" beginning with the 1998 models. Newer transmissions are referred to as 4R70E, 4R75W or 4R75E to differentiate them from previous models. The 4R75E/W has greater torque capacity (75 x 10 = 750 Lb-Ft) than previous models.

The most practical modification for the 4R70W is the J-mod. It involves modifying the valve body gaskets and changing some accumulator springs to alter the shift timing of the transmission. It encompasses modifications specified by one of the Ford engineers that designed the transmission. It offers quicker shifting, smoother operation, and increased service life. All parts can be bought at Ford dealers for less than $60 including the fluid.

A 20,000+ GVW cooler is highly recommended for all vehicles. Breakdown of the transmission fluid often results in "converter shudder" (feels like driving over rumble strips) where converter tries to maintain a steady slip rate during lock-up, but alternates between slipping and grabbing. Frequent fluid changes, especially when used for towing, are the single best method to prevent shudder. Shudder occurs because the torque converter never fully enters "lock-up", but is designed to slip slightly during steady-state operation. The reason Ford decided to use "Steady-state-slip" is often discussed but no complete answer has been found.

4R7xx Usage

2002

  • 4R70W used in all applications

2003

  • 4R75W used in Mercury Marauder, V8 Mustang (GT and Mach 1), and 5.4 L trucks (F150, Van, and Expedition)
  • 4R70W used in all other applications (V6 Mustang, 4.6 L Van, 4.2 L F150, 4.6 L F150, and Crown Vic/Grand Marquis/Towncar)

2004

  • 4R75E used in 5.4 L-3v F150
  • 4R70E used in 4.6 L F150 (except F150 Heritage)
  • 4R75W used in Mercury Marauder, V8 Mustang (GT and Mach 1), and 5.4 L-2v trucks (Van, and Expedition)
  • 4R70W used in all other applications (V6 Mustang, 4.6 L Van, 4.6 L Expedition, Crown Vic/Grand Marquis/Towncar, and F150 Heritage).

2005

  • 4R75E used in 5.4 L trucks (F150, Van, and Expedition)
  • 4R70W used in F150 Heritage (sold only in Mexico)
  • 4R70E used in all other applications (4.6 L Van, Crown Vic/Grand Marquis/Towncar, and 4.6 L F150 (except F150 Classic (sold only in Mexico))

2006 to 2008

  • 4R70W used in F150 Heritage (sold only in Mexico)
  • 4R75E used in all other applications (Van, Crown Vic/Grand Marquis/Towncar, and F150 (except F150 Heritage (sold only in Mexico))

See also