Mercedes-Benz first series automatic transmission

The Mercedes-Benz first series of automatic transmission was produced from 1961 to 1983 in 4- and 3-speed variants for Mercedes-Benz passenger cars. In addition, variants for commercial vehicles were offered until the mid-1990s.
This transmission was the first Mercedes-Benz automatic transmission in-house developing. Before this, the company used semi-automatic systems like a vacuum-powered shifting for overdrive or the "Hydrak" hydraulic automatic clutch system. Alternatively, they bought automatic transmissions of other vendors, such as the Detroit gear 3-speed automatic transmission from BorgWarner for the 300 c and 300 d.
The automatic transmissions are for engines with longitudinal layout for rear-wheel-drive layout passenger cars. The control of the fully automatic system is fully hydraulic and it uses electrical wire only for the kickdown solenoid valve and the neutral safety switch.
Physically, it can be recognized for its pan which uses 16 bolts.

Key Data

1961: K4A 025
— 4-Speed Transmission With 2 Planetary Gearsets —

Layout

The K4A 025 is the first of the series, launched in April 1961 for the W 111 220 SEb, later replaced with the more reliable K4C 025. It is a 4-speed unit and uses fluid coupling.
The design of the transmission results in poor shifting comfort, which does not meet Mercedes-Benz standards. This applies in particular to the change from 2nd to 3rd gear, which requires a group change, i.e. affects all shift elements.

Specifications

For this first 4-speed model 8 main components are used. It is the only exemption which uses only 2 planetary gearsets for 4 speeds.

1964: K4B 050 And Follow-Up Products
— 4-Speed Transmissions With 3 Planetary Gearsets —

Layout

The Mercedes-Benz 600, unveiled in September 1963 at the International Motor Show in Frankfurt, it went into production in September 1964 and was the first post-war "Grand Mercedes", powered by the Mercedes-Benz M100 engine. This made a gearbox for the highest demands of luxury vehicles necessary. The design of the gearbox in the range was out of the question from the outset. The introduction of the 600 was therefore taken as an opportunity to develop a completely new design for the automatic transmission.

Models

1964: K4B 050

The first model with this new layout was the K4B 050. Beside the new layout the number of pinions is doubled from 3 to 6 to handle the much higher torque of the big block V8 engine.

1967: K4C 025

After the satisfactory experience with the new design, it was adopted in 1967 for the new core model K4C 025 of the first automatic transmission series from Mercedes-Benz. With the small block V8 engine M 116, the K4A 040 was launched as a reinforced version of the same design.

1969: K4A 040

With the introduction of the V8 cylinder engines of the M 116 series with a displacement of 3.5 liters, the automatic transmission range was expanded to include the K4A 040 model, which is a reinforced version of the K4C 025 with the same gear ratios to accommodate the increased torque.

1972: W4B 025

When the torque converter technique was fully established, the fluid coupling was replaced by a torque converter for the smaller engines, which leads to the W4B 025. Used in L4, L5 and L6 engines due to its lower torque output. In normal situations, it rests stationary in 2nd gear, but it will use 1st gear when the vehicle starts moving and throttle is applied or if L position is selected in gear selector.

Variants For Commercial Cars

The W4A 018 was derived from the W4B 025 for light-duty trucks and vans up to and off-road vehicles, the W4B 035 from the W4B 025 and K4A 040 for medium-duty trucks up to. The main difference is the use of straight-cut planetary gearsets instead of helical-cut ones for better fuel efficiency at the price of lower noise comfort.

Specifications

For this second 4-speed models 8 main components are used.

1971: W3A 040 And Follow-Up Products
— 3-Speed Transmissions With 2 Planetary Gearsets —

Layout

When the torque converter technique was fully established, 3-speed units, the W3A 040 and W3B 050 is combined with V8 engines, and it uses torque converter instead of fluid coupling. The transmission saves 1 planetary gearset and uses the same housing as the 4-speed versions. The free space therefore is used to reinforce the shift elements to handle the higher torque of the V8 engines.
First the W3A 040 was released for the all new M117 V8 engine of the W 108 and W 109 in 1971. The second in the series is the W3B 050, which was released initially for the W 116 450 SE/SEL in 1973. At that time the 4-speed transmission for the 350 SE/SEL was replaced by this 3-speed model. The reinforced W3B 050 reinforced is the strongest of the series, able to handle the input of the enlarged version of the M 100, the biggest Mercedes-Benz engine in post-war history, exclusively used in the W 116 450 SEL 6.9.

Specifications

For the 3-speed models 7 main components are used, which shows economic equivalence with the direct competitor.

Applications

K4A 025

1961–1965 · 1961–1968 W 111
1961–1965 · 1962–1968 W 112
1961–1968 W 110
1963–1971 W 113
1965–1968 W 108/W 109

K4B 050

1964–1981 600 (W 100)
1968–1972 300 SEL 6.3 (W 109)

K4C 025

1968–1971 W 111
1968–1972 W 108/W 109

Chassis code	Car model	Engine code	Transmission code
114.015 and 114.615	230.6	180.954	722.203
114.017 and 114.617	230.6 Lang	180.954	722.203
114.011 and 114.611	250	130.923	722.204
114.023 and 114.623	250 C	130.923	722.204
114.060 and 114.660	280	110.921	722.202
114.073 and 114.673	280 C	110.921	722.202
114.062 and 114.662	280 E	110.981	722.200
114.072 and 114.672	280 CE	110.981	722.200
115.015 and 115.615	200	115.923	722.205
115.010	220	115.920	722.205
115.115 and 115.715	200 D	615.913	722.206
115.110 and 115.710	220 D	615.912	722.206
115.112	220 D Lang	615.912	722.206

K4A 040

Chassis code	Car model	Engine code	Transmission code	Notes
109.057	300 SEL 3.5	3.5 L M 116 V8	722.201	worldwide except USA
108.067	280 SE 3.5	3.5 L M 116 V8	722.201	worldwide except USA
108.068	280 SEL 3.5	3.5 L M 116 V8	722.201	worldwide except USA

Chassis code	Car model	Engine code	Transmission code
107.043	350 SL	116.982 116.984	722.201
107.023	350 SLC	116.982 116.984	722.201

W3A 040

Chassis code	Car model	Engine code	Transmission code	Notes
109.056	300 SEL 4.5	4.5 L M 117 V8	722.000	USA only
108.057	280 SE 4.5	4.5 L M 117 V8	722.000	USA only
108.058	280 SEL 4.5	4.5 L M 117 V8	722.000	USA only

Chassis code	Car model	Engine code	Transmission code	Notes
107.043	350 SL	116.982 116.984	722.002	-
107.023	350 SLC	116.982 116.984	722.002	-
107.044	450 SL	117.982 117.985	722.004	USA and Japan only
107.024	450 SLC	117.982 117.985	722.004	USA and Japan only

Chassis code	Car model	Engine code	Transmission code	Notes
116.028	350 SE	116.983 116.985	722.002	-
116.029	350 SEL	116.983 116.985	722.002	-
116.032	450 SE	117.983 117.986	722.004	USA and Japan only
116.033	450 SEL	117.983 117.986	722.004	USA and Japan only

W3B 050

Chassis code	Car model	Engine code	Transmission code	Notes
107.044	450 SL	117.982 117.985	722.001	worldwide except USA and Japan
107.024	450 SLC	117.982 117.985	722.001	worldwide except USA and Japan

Chassis code	Car model	Engine code	Transmission code	Notes
116.032	450 SE	117.983 117.986	722.001	worldwide except USA and Japan
116.033	450 SEL	117.983 117.986	722.001	worldwide except USA and Japan
116.036	450 SEL 6.9	100.985	722.003	722.003 W3B 050 reinforced

1977 - 1984 Porsche 928

W4B 025

Chassis code	Car model	Engine code	Transmission code
107.042	280 SL	110.982 110.986 110.990	722.103 722.112
107.022	280 SLC	110.982 110.986	722.103 722.112

Chassis code	Car model	Engine code	Transmission code
114.015 and 114.615	230.6	180.954	722.105
114.017 and 114.617	230.6 Lang	180.954	722.105
114.011 and 114.611	250	130.923	722.104
114.023 and 114.623	250 C	130.923	722.104
114.060 and 114.660	280	110.921	722.102
114.073 and 114.673	280 C	110.921	722.102
114.062 and 114.662	280 E	110.981	722.103
114.072 and 114.672	280 CE	110.981	722.103
115.015 and 115.615	200	115.923	722.106
115.017	230.4	115.951	722.110
115.115 and 115.715	200 D	615.913	722.107
115.110 and 115.710	220 D	615.912	722.107
115.112	220 D Lang	615.912	722.107
115.117	240 D	616.916	722.108
115.119	240 D Lang	616.916	722.108
115.114	240 D 3.0	617.910	722.109

Chassis code	Car model	Engine code	Transmission code	Notes
116.020	280 S	110.922	722.100 722.102 722.111	-
116.024	280 SE	110.983 110.985	722.101 722.103 722.112	-
116.025	280 SEL	110.983 110.985	722.101 722.103 722.112	-
116.120	300 SD	617.950	722.120	USA only

Chassis code	Car model	Engine code	Transmission code	Notes
123.020	200	115.938 115.939	722.115	-
123.220	200	102.920 102.939	722.121	-
123.280	200 T	102.920 102.939	722.121	-
123.023	230	115.954	722.119	-
123.083	230 T	115.954	722.119	-
123.043	230 C	115.954	722.119	-
123.223	230 E	102.980	722.122	-
123.283	230 TE	102.980	722.122	-
123.243	230 CE	102.980	722.122	-
123.026	250	123.920 123.921	722.113	-
123.086	250 T	123.920 123.921	722.113	-
123.028	250 Lang	123.920 123.921	722.113	-
123.030	280	110.923	722.111	-
123.050	280 C	110.923	722.111	-
123.033	280 E	110.984 110.988	722.112	-
123.093	280 TE	110.984 110.988	722.112	-
123.053	280 CE	110.984 110.988	722.112	-
123.120	200 D	615.940	722.116	-
123.126	220 D	615.941	722.116	-
123.123	240 D	616.912	722.117	-
123.183	240 TD	616.912	722.117	-
123.125	240 D Lang	616.912	722.117	-
123.130	300 D	617.912	722.118	-
123.190	300 TD	617.912	722.118	-
123.132	300 D Lang	617.912	722.118	-
123.150	300 CD	617.912	722.118	USA only

Mercedes-Benz first series automatic transmission

Key Data

1961: K4A 025&mdash; 4-Speed Transmission With 2 Planetary Gearsets&nbsp;&mdash;

Layout

Specifications

1964: K4B 050 And Follow-Up Products&mdash; 4-Speed Transmissions With 3 Planetary Gearsets&nbsp;&mdash;

Layout

Models

1964: K4B&nbsp;050

1967: K4C&nbsp;025

1969: K4A&nbsp;040

1972: W4B&nbsp;025

Variants For Commercial Cars

Specifications

1971: W3A 040 And Follow-Up Products&mdash; 3-Speed Transmissions With 2 Planetary Gearsets&nbsp;&mdash;

Layout

Specifications

Applications

K4A 025

K4B&nbsp;050

K4C&nbsp;025

K4A&nbsp;040

W3A&nbsp;040

W3B&nbsp;050

W4B&nbsp;025

1961: K4A 025
— 4-Speed Transmission With 2 Planetary Gearsets —

1964: K4B 050 And Follow-Up Products
— 4-Speed Transmissions With 3 Planetary Gearsets —

1964: K4B 050

1967: K4C 025

1969: K4A 040

1972: W4B 025

1971: W3A 040 And Follow-Up Products
— 3-Speed Transmissions With 2 Planetary Gearsets —

K4B 050

K4C 025

K4A 040

W3A 040

W3B 050

W4B 025