The Mercedes 722.9 7-speed automatic transmission, also known as the 7G-Tronic or NAG2, was produced from 2003 to 2022 and was installed across virtually the entire Mercedes-Benz lineup, as well as on Infiniti models as the RE7R24A. Seven versions of the automatic transmission are available: W7A400, W7X550, W7X700, W7A700, W7B700, W7C700, and W7C1000. Modifications include the AMG SpeedShift MCT 7 and AMG SpeedShift TCT 7.
This series includes: 722.3, 722.4, 722.5, 722.6, 722.7, 722.9, 725.0.
Small NAG2: W7A400.
Middle NAG2: W7X550, W7X700.
Large NAG2: W7A700, W7B700, W7C700.
AMG modifications: W7C1000.
Specifications
| Type | automatic transmission |
| Number of gears | 7 |
| Type of drive | rear |
| Engine volume, l | up to 2.0 (Small NAG2) up to 3.5 (Middle NAG2) up to 5.5 (Large NAG2) up to 6.0 (AMG modifications) |
| Torque output, Nm | up to 400 (Small NAG2) up to 550/700 (Middle NAG2) up to 700 (Large NAG2) up to 1000 (AMG modifications) |
| Recommended oil | ATF MB 236.15 (Small NAG2) ATF MB 236.14 / 236.15 (Middle NAG2) ATF MB 236.14 / 236.15 (Large NAG2) ATF MB 236.15 (AMG modifications) |
| Oil capacity, liter | 9.0 (Small NAG2) 9.0 (Middle NAG2) 9.7 (Large NAG2) 7.7 (AMG modifications) |
| Partial replacement, liter | 8.3 (Small NAG2) 8.3 (Middle NAG2) 9.0 (Large NAG2) 7.1 (AMG modifications) |
| Maintenance | every 50 000 km |
| Gearbox lifespan, km | ~400 000 km |
| Weight, kg | 82 |
In 2003, a seven-speed automatic transmission debuted on the E-Class and S-Class models with V8 engines. This is a classic hydromechanical automatic transmission for longitudinally mounted vehicles, consisting of three planetary gearsets, four brake clutches, and three clutches. The first to appear was the W7A700, followed by an updated version, the W7B700, and only later was a version for less powerful V6 engines, the W7X550, launched.
In 2010, the second generation of the 7-speed automatic transmission, the 7G-Tronic Plus, debuted. It featured an additional electric oil pump for the start-stop system, a new torque converter with a pendulum damper, and a number of other minor improvements. The second generation of the transmission includes the W7C700, W7X700, and the highly powerful W7C1000. A version for 4-cylinder petrol engines with the index W7A400 has also finally appeared.
Gear ratios Mercedes 722.9
Using the example of a 2007 Mercedes E500 with a 5.5 liter engine:
| Main | 2.47 |
| 1st | 4.377 |
| 2nd | 2.859 |
| 3rd | 1.921 |
| 4th | 1.368 |
| 5th | 1.000 |
| 6th | 0.820 |
| 7th | 0.728 |
| Reverse | 3.416 |
Using
The transmission was installed on:
- Infiniti Q50 1 (V37) in 2013 – 2020;
- Infiniti Q60 2 (CV37) in 2016 – 2022;
- Infiniti Q70 1 (Y51) in 2015 – 2022;
- Mercedes C-Class W203 in 2005 – 2007; C-Class W204 in 2007 – 2015; C-Class W205 in 2014 – 2016;
- Mercedes CL-Class C215 in 2003 – 2006; CL-Class C216 in 2006 – 2013; CL-Class C217 in 2015 – 2017;
- Mercedes CLC-Class C203 in 2008 – 2011;
- Mercedes CLK-Class C209 in 2004 – 2009;
- Mercedes CLS-Class C219 in 2004 – 2010; CLS-Class C218 in 2011 – 2017;
- Mercedes E-Class W211 in 2003 – 2009; E-Class W212 in 2009 – 2016;
- Mercedes GL-Class X164 in 2006 – 2012; GL-Class X166 in 2012 – 2015;
- Mercedes GLE-Class W166 in 2015 – 2018;
- Mercedes GLK-Class X204 in 2008 – 2015;
- Mercedes ML-Class W164 in 2005 – 2011; ML-Class W166 in 2011 – 2015;
- Mercedes R-Class W251 in 2004 – 2017;
- Mercedes S-Class W220 in 2003 – 2005; S-Class W221 in 2005 – 2013; S-Class W222 in 2013 – 2017;
- Mercedes SL-Class R230 in 2006 – 2011; SL-Class R231 in 2011 – 2016;
- Mercedes SLK-Class R171 in 2004 – 2011; SLK-Class R172 in 2011 – 2015;
- Mercedes V-Class W447 in 2014 – 2019;
- Mercedes Vito W447 in 2014 – 2019;
- SsangYong Chairman 2 (W200) in 2008 – 2017;
- SsangYong Rodius 2 (A150) in 2015 – 2019;
- SsangYong Rexton 1 (Y200) in 2015 – 2017; Rexton 2 (Y400) in 2017 – 2020.
Disadvantages of the Mercedes 722.9 gearbox
- The first automatic transmissions were very unreliable and often didn’t even make it to the end of their warranty period. The control board usually failed, and the K1 drum or gearboxes would disintegrate. They also suffered from the well-known problem of defective radiators, which was common in their predecessors.
- Many models with a 7-speed automatic transmission are equipped with a steering wheel-mounted gear selector, which itself often fails and controls an equally unreliable servo. The problem is compounded by the fact that the car cannot be pushed or towed after this.
- The electronic transmission control unit is located in the crankcase along with the valve body and is very sensitive to hot oil. Therefore, frequent overheating significantly reduces its service life. In addition to the board itself, specialized service stations regularly replace the speed sensors.
- Like all automatic transmissions with active torque converter lockup, this transmission suffers from contamination of the valve body and solenoids from wear products of the torque converter friction linings. On large and powerful models, gearboxes and even gearbox bell housings can be damaged.
