Mercedes-Benz 4G-Tronic transmission

The Mercedes-Benz 4G-Tronic transmission was produced from 1979 to 1996 in W4A 028, W4A 040 (both type 722.3), W4A 020 (type 722.4), and W5A 030 (type 722.5) variants.

Mercedes-Benz W4A 028 · W4A 040 · W4A 020 · W5A 030
Overview
ManufacturerDaimler AG
Production1979–1996
Body and chassis
Class4-speed longitudinal automatic transmission
Chronology
PredecessorMercedes-Benz first series automatic transmission
Successor5G-Tronic (Type 722.6)

Abstract

It's a hydraulically operated four speed automatic without lock-up that replaced the similarly designed W3A 040, W3B 050, and W4B 025 family of automatic transmission in 1979. It is calibrated to take off in second gear to reduce "creeping" and provide a smoother ride. The transmission will select 1st only if the selector is in "2" or in case of abrupt acceleration. Other attributes of this transmission include a 2-3 shift delay when the engine is cold in order to speed up catalyst warm-up. 4th gear is a 1:1 ratio.

The W4A 040 and the W4A 020 were used until mid-1996. The W4A 028 variant was used for off-road applications (RWD and 4X4). The W5A 030 is basically the same transmission with an additional electrically controlled 5th gear for overdrive in a directly to the main body attached separate housing. It was sold for an extra charge. They were replaced with the more modern and economic 5G-Tronic (Type 722.6) transmission that features a torque converter lock-up and fully electronic control.

It is considered by enthusiasts to be one of the most reliable transmissions ever built by Mercedes-Benz with some examples exceeding 300,000 miles of service.

Specifications

Basic concept

For this W4A-models 4 forward gears[lower-alpha 1] using 8 main components[lower-alpha 2][1] show economic equivalence with the direct predecessor.[lower-alpha 3] 5 forward gears[lower-alpha 4] out of 11 main components[lower-alpha 5][1] and the need of two housings[lower-alpha 6] and two different controls[lower-alpha 7] turn out the W5A 030 as the least economically designed automatic transmission ever manufactured for passenger cars. Obviously a transition solution: the direct successor, launched in 1996, requires 9 main components,[lower-alpha 8] one housing and one control.[lower-alpha 9]

Gear ratios
Gear Teeth and Ratios Planetary Gearset: Teeth Count Total Avg.
Ravigneaux Simple
Model

Type

 Version

First Delivery

 Sun 1.1

Ring 1.1

 Sun 1.2

Ring 1.2

 Sun 2

Ring 2

 Sun 3

Ring 3

 Brakes

Clutches

 Ratio

Span

 Gear

Step

Gear 1 2 3 4 5 R
W4A 040

722.3

 392 Nm · 289 lb·ft

1979[1]

 34

50

 50

78

 34

78

 3

2

 3.6759 1.5433
Ratio 3.6759 2.4123 1.4359 1.0000 - 5.1388
W4A 020

722.4

 196 Nm · 145 lb·ft

1982[1]

 26

42

 42

78

 38

78

 3

2

 4.2491 1.6197
Ratio 4.2491 2.4078 1.4872 1.0000 - 5.6692
W4A 040 II

722.3

 392 Nm · 289 lb·ft

1985[1]

 26

46

 46

78

 34

78

 3

2

 3.8707 1.5701
Ratio 3.8707 2.2475 1.4359 1.0000 - 5.5857
W4A 028

722.3[2]

 274 Nm · 202 lb·ft

1990

 26

46

 46

78

 34

78

 3

2

 3.8707 1.5701
Ratio 3.8707 2.2475 1.4359 1.0000 - 5.5857
W5A 030

722.5

 294 Nm · 217 lb·ft

1990[1]

 26

46

 46

78

 34

78

 26

78

 4

3

 5.1609 1.5072
Ratio 3.8707 2.2475 1.4359 1.0000 0.7500 - 5.5857

Applications

The 4G-Tronic has been used only in a plethora of Mercedes-Benz cars.

W4A 028 (Type 722.3)

W4A 040 I+II (Type 722.3)
  • 1981-1989 R107 and C107
  • 1989-1996 R129

W4A 020 (Type 722.4)
  • 1985-1996 W124
  • 1982-1993 W201
  • 1993-1996 W202
  • 1995-1996 W210

W5A 030 (Type 722.5)
  • 1990-1996 W124
  • 1991-1996 W140
  • 1995-1996 W210
  • 1990-1996 R129
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See also

Notes
  1. plus 1 reverse gear
  2. 3 planetary gearsets (Ravigneaux planetary gearset considered as 2), 3 brakes, 2 clutches
  3. 3 simple planetary gearsets, 3 brakes, 2 clutches
  4. plus 1 reverse gear
  5. 4 planetary gearsets (Ravigneaux planetary gearset considered as 2), 4 brakes, 3 clutches
  6. regular bousing for gear 1 to 4 and reverse gear · supplemental housing for gear 5
  7. hydraulic for gear 1 to 4 and reverse gear · electronic for gear 5
  8. 3 simple planetary gearsets, 3 brakes, 3 clutches
  9. electronic

References
  1. Hans Joachim Foerster · Automatische Fahrzeuggetriebe · Page 171 and 192 · Berlin and Heidelberg 1991 · Print ISBN 978-3-642-84119-4 · Online ISBN 978-3-642-84118-7
  2. https://up.picr.de/32855333vn.pdf
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