Mercedes-Benz 4G-Tronic transmission


The Mercedes-Benz 4G-Tronic transmission was produced from 1979 to 1996 in W4A 028, W4A 040, W4A 020, and W5A 030 variants.

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. 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 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 using 8 main components show economic equivalence with the direct predecessor. 5 forward gears out of 11 main components and the need of two housings and two different controls 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, one housing and one control.

Gear ratios

Applications

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

W4A 028 (Type 722.3)