TorqueFlite

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TorqueFlite
Manufacturer Chrysler Corporation
Production 1956–
Predecessor PowerFlite
Class 3- or 4-speed automatic

TorqueFlite (also spelled Torqueflite) was the trademarked name of Chrysler Corporation's three-speed automatic transmission, which was introduced late in the 1956 model year. TorqueFlite was introduced on the heels of the company's two-speed PowerFlite automatic, which made its debut in 1954. In the 1990s the TorqueFlite name was dropped and the transmissions were referred to by a model number referring to their torque rating and gear set, although some models remained completely unchanged.

Contents

[edit] History

The first Torqueflites provided three speeds forward plus reverse. Gear ratios were 2.45:1 in first, 1.45 in second, and 1.00 in third. The transmission was controlled by a series of pushbuttons located on the vehicle's dashboard to the left of the steering column. Button arrangement varied by vehicle model and year; sequence was Reverse, Neutral, Drive, Second, and First, from top to bottom with vertically-arrayed buttons, from left to right with horizontally-arrayed buttons, and clockwise starting at upper left with clustered buttons. A parking lock was not provided until the advent of the aluminum-case Torqueflite in 1960 (standard-duty A-904) 1962 (heavy-duty A-727), at which point a lever was added adjacent to the pushbuttons: Throwing the lever to the "Park" position placed the car into Neutral and engaged a lock pawl on the transmission's output shaft. Throwing the park lever out of "Park" position unlocked the shift buttons so that a driving range could be selected. The buttons were replaced by conventional steering column- or floor-mounted shift levers in all automatic Chrysler-built vehicles for the 1965 model year.

Unlike some competing automatic transmissions of its era, Torqueflite started in first gear when placed in Drive; Ford Motor Company's Ford-O-Matic and Borg-Warner's automatics started in second unless started in Low. Selecting 2 or 1 locked out third and second gear, respectively, which allowed the driver to manually control shift points. Second-gear starts were not available by any means.

1962 brought the addition of a canister-style fluid filter factory-installed in the cooler line. For 1964, the canister filter was eliminated, and the transmission's internal intake screen was replaced by an efficient Dacron filter. Fluid life starting in 1964 was extended from 12,000 to 50,000 miles (80,000 km), providing justification for the deletion of the drain plug from the oil pan.

For 1966, the twin-cable shift and park control mechanism was replaced by a simple, single-action solid shift control linkage consisting of a series of pushrods, rotating rods and levers. The rear pump was eliminated, which simplified and cost-reduced the transmission but rendered push-starting impossible; Chrysler engineers reasoned that improved electrical and fuel systems reduced the need to push-start vehicles, and safety concerns weighed against doing so. The gated shift quadrants also permitted the deletion of the reverse safety blocker valve which, in TorqueFlites made through 1965, had shifted the transmission harmlessly into Neutral if the Reverse position were selected with the vehicle moving forward above approximately 3 mph (5 km/h).

In 1968, part-throttle downshift functionality was added to A-904 transmissions used with 6-cylinder engines. This feature permitted the transmission to shift from third to second gear in response to moderate accelerator pressure. Previously, an automatic 3-2 downshift occurred only if the driver pushed the accelerator to the floor. This change was made to maintain acceptable in-town performance with the newly-adopted taller final-drive ratios in the rear axle (2.76:1 rear axle gears were furnished in applications previously equipped with 2.93:1 or 3.23:1 gearsets). Part-throttle downshift functionality was extended to V8 A-904s in 1969, and to most A-727 transmissions in 1970 to 1971.

In 1978, most TorqueFlite transmissions gained a lock-up torque converter (a clutch to mechanically connect the impeller and turbine of the torque converter, eliminating slippage) in the interests of improved fuel economy. This addition required the removal of the torque converter drain plug.

For 1980, a wide-ratio gearset was released for the A904, A998 and A999, with 2.74:1 in first, 1.54 in second, and 1.00 in third.

TorqueFlite was an available option or standard equipment, depending on model and year, on all Chrysler products (Plymouth, Dodge, DeSoto, Chrysler and Imperial) and on various American Motors (AMC), Jeep, International Harvester, Maserati Quattroporte, Monteverdi [1] and Bristol [2] brand vehicles as well. AMC referred to the transmission as the Torque-Command. When installed in Dodge trucks and vans, the transmission was marketed as LoadFlite.

In the 1990s the transmissions were renamed, however the TorqueFlite remains the basis of all current Chrysler designed transmissions. Jeep used several other manufacturers transmissions until 1997, and Mercedes-Benz uses its own design identified by the number "722". Also several of the pickup lines now use transmissions from various sources.

[edit] Technology

Torqueflites use a torque converter and the so-called "Simpson gearset," two identical planetary gearsets sharing a common sun gear. Chrysler Corporation licensed this gearset from Simpson in 1955.

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[edit] Rear-wheel drive transmissions

[edit] A488

The original TorqueFlite was designated A488, with a cast iron case and no parking pawl.

[edit] A727

The A488 was replaced in 1962 with the A727 (later 36RH, 37RH), with an aluminum case to reduce weight by about 60 lb (27 kg). The A727 incorporated a parking pawl and various internal improvements. The 727 used either a 10.75 in or an 11.75 in (273 or 298 mm) torque converter. The heavier-duty A727 TorqueFlites became popular (and remain popular to this day) for drag racing and monster truck applications because of their controllability and strength.

[edit] A518

The A518, later 46RH (hydraulic) and 46RE (electronic), is an A727 derivative with overdrive. Starting in the early 1990s, it was used in trucks, vans, and V8 applications. The electronic overdrive section made the final gear ratio 0.69. It has a GCVW of 14000 lb (6400 kg).

Gear ratios:

1 2 3 4 R
2.45 1.45 1.00 0.69 2.21

Applications:

[edit] A618

The A618, later 47RH (hydraulic) and 47RE (electronic), is a heavier-duty version of A518. It was used in trucks and vans starting in the mid-1990s. While currently used with some internal changes when coupled to the 5.9 Liter Cummins Turbo-Diesel and the 8.0 V-10 applications, it's still a 727 with overdrive and better, stronger internal parts. It has an Input Torque Rating of 450 lb·ft (610 N·m) and GCVW of 19000 lb (8600 kg).

Gear ratios:

1 2 3 4 R
2.45 1.45 1.00 0.69 2.21

Applications:

[edit] 48RE

The 48RE is an electronically governed 4-speed overdrive heavy-duty automatic transmission designed to replace the 47 series automatic. It has been a better performer over the dated 47 series automatics and is stronger as well.

Gear ratios:

1 2 3 4 R
2.45 1.45 1.00 0.69 2.21

Applications:

[edit] A904

For standard-duty applications in smaller and lighter vehicles with Slant-6 or small V8 engines, with relatively modest torque and a compact case, the A904 (later 30RH) was introduced in 1960. This transmission used a 10.75 in (273 mm) torque converter. There was also a "Baby" case version of this transmission used in Dodge Colt/Plymouth Champ imports(made by Mitsubishi in Japan), these used a 10 in torque converter.

[edit] A998/A999

The A998/A999 (later 31RH, 32RH, respectively) was a heavier-duty, wide-ratio version of the small-frame A904 transmission, for use with medium-power V8 engines and the more powerful 3.9L truck engine that replaced the slant six.

The 904 was equipped with three direct friction plates, the 998 had four, and the 999 came with either four or five.

These automatics had lower gear ratios to allow the lower powered engines offered from Chrysler a mechanical advantage over the more powerful ones.

[edit] A500

The A500, later 40RH/42RH (hydraulic) and 40RE/42RE (electronic), was an A904 derivative used in trucks and vans. Introduced in the 1989 model year on a limited basis, it was the first light-duty Chrysler four-speed automatic and was found behind the 3.9L and 5.2L engines for light duty purposes. A tailshaft overdrive unit was bolted to the rear of the case to provide a total of four forward speeds. It has a GCVW of 7800 lb (3540 kg). Was replaced by the 42RLE in 2004

Gear ratios:

1 2 3 4 R
2.74 1.54 1.00 0.69 2.21

Applications:

  • 1989-2001 Dodge Ram pickup 150/1500 V6/V8(2WD)
  • 1989-2003 Dodge Ram Van B150/B250 V6/V8
  • 1989-2003 Dodge Dakota V6
  • 1993-2004 Jeep Grand Cherokee I6 (actually used a beefier version called the 44RE)

[edit] Front-wheel drive transaxles

The A404, A413, A470, and A670 are front-wheel drive transaxle derivatives of the A904 Torqueflite.

In the late 1970s, Chrysler designed the A404 TorqueFlite 3-speed automatic transaxle for its front wheel drive Dodge Omni and Plymouth Horizon subcompact cars. This transaxle would be upgraded in the 1980s into the A413 and A670 units, which were progressively heavier-duty, for Chrysler's K-cars and their derivatives, including the minivans. The 4-speed Ultradrive electronic 4-speed automatic transaxle would eventually replace it, but the 3-speed lasted for more than a decade after the 1989 debut of the 4-speed unit.

[edit] A404

The light-duty A404 was used with the smallest straight-4 engines from Chrysler, commonly the 1.7 L Volkswagen unit.

[edit] A413 or 31TH

The A404 was strengthened to become the A413 (later 31TH) in 1981. This was used with Chrysler's 2.2 L and 2.5 L straight-4 K-car engines. It was available both with and without a lockup torque converter. This transmission was also used in the Dodge Neon from 1995 to 2001. The A413 is broadly similar in concept to Ford's ATX 3-speed unit.

[edit] A415

The A415 was developed for the 1.6 L Simca 1100 engine, but was not released for series production.

[edit] A470

The A470 was an additionally-strengthened version of the transaxle, used with the 2.6 L Mitsubishi Astron engine in the K-cars from 1981 to 1985 and minivans from 1984 through 1987.

[edit] A670

The highest-specification 3-speed transaxle was the A670. It was used with the 3.0 L 6G72 V6 engine in Chrysler's cars and minivans from 1987 through 2000.

Gear ratios:

1 2 3 R Final
2.69 1.55 1.00 2.10 3.02

[edit] See also

[edit] References