Mercedes-Benz 7G-Tronic transmission
|Body and chassis|
|Class||7-speed longitudinal automatic transmission|
7G-Tronic (coded 722.9) is Mercedes-Benz's trademark name for its seven-speed automatic transmission. This fifth-generation transmission was introduced in the Autumn of 2003 on 8-cylinder models, and was the first seven-speed automatic transmission ever used on a production passenger vehicle.
The 7G-Tronic initially debuted on five different eight-cylinder models: the E500, S430, S500, CL500, and SL500. It also soon became available on many six-cylinder models. Turbocharged V12 engines, four cylinder applications and commercial vehicles continued to use the older 5G-Tronic for many years.
The company claims that the 7G-Tronic can save up to 0.6 litres of fuel per 100 kilometers (depending on the car) and has shorter acceleration times and quicker intermediate sprints than the outgoing 5-speed automatic transmission.
The 7G-Tronic has two reverse gear ratios: 3.416 and 2.231. The winter mode, also recently named 'comfort' mode, starts out in 2nd forward and 2nd reverse.
The transmission can skip gears when downshifting. It also has a lockup torque converter on all seven gears, allowing better transmission of torque for improved acceleration. The transmission's case is made of magnesium, a first for the industry, to save weight.
The 7G-Tronic is the fifth-generation transmission for Mercedes-Benz. About 65 percent of Mercedes-Benz C-Class sedans, wagons, and sport coupes are purchased with automatic transmissions (with that figure rising). However, about 88 percent of Mercedes-Benz E-Class sedans and wagons are purchased with automatic transmissions, and automatic transmissions are standard on the Mercedes-Benz S-Class.
The 7G-Tronic is currently available on the SsangYong Chairman W, SsangYong Rexton W and SsangYong New Rodius/KorandoTurismo (in South Korea)/Turismo (in UK).
In July 2009, Mercedes-Benz announced they are working on a new nine-speed automatic.
AMG SpeedShift MCT
The MCT transmission is essentially the 7G-Tronic automatic transmission without a torque converter. Instead of a torque converter, it uses a compact wet startup clutch to launch the car from a stop, and also supports computer-controlled double declutching. The MCT (Multi-Clutch Technology) acronym refers to a planetary (automatic) transmission’s multiple clutches and bands for each gear.
The MCT is fitted with four drive modes: “C” (Comfort), “S” (Sport), “S+” (Sport plus) and “M” (Manual) and boasts 100 millisecond shifts in "M" and "S+" modes. MCT-equipped cars are also fitted with the new AMG DRIVE UNIT with innovative Race Start function. The AMG DRIVE UNIT is the central control unit for the AMG SPEEDSHIFT MCT 7-speed sports transmission and all driving dynamics functions. The driver can change gears either using the selector lever, or by nudging the steering-wheel shift paddles. The new Race start Function is a launch control system which enables the driver to call on maximum acceleration, while ensuring optimum traction of the driven wheels.
|7G TRONIC||4.377||2.859||1.921||1.368||1.00||.82||.728||-3.416||-2.231||application specific|
AMG SpeedShift (2004-)
Sporty, performance-oriented version with the same gear rations. First used in 2005 Mercedes-Benz SLK 55 AMG.
In 2007, 7G TRONIC transmission with AMG SPEEDSHIFT was also called '7G TRONIC Sport'.
Common Problems with 7G-Tronic
There are different common problems with NAG2 (7G-Tronic) electronic-control-units. The most frequent failures are the following troublecodes:
- P0717 Input / Turbine Speed Sensor Circuit No Signal
- P0718 Input / Turbine Speed Sensor Circuit Intermittent
To fix this Problem there are existing 2 options. 1st = install a new control unit (expensive and Mercedes-Benz dealer have to do programming of electronic) 2nd = repair of the damaged electronic (no programming or coding by Mercedes-Benz)
Informationpage (from Germany) about repair possibilities available under external links.
||This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. (November 2009) (Learn how and when to remove this template message)|
- "7G-Tronic: Mercedes-Benz presents the world's first seven-speed automatic transmission for passenger cars" (PDF). DaimlerChrysler press release.
- 19 July 2010. "Merc plans nine-speed auto'". Autocar.co.uk. Retrieved 2010-07-20.
- New 7-speed AMG Speedshift MCT debuts
- The new Mercedes-Benz SLK-Class: Celebrating its world premiere at the Geneva Motor Show
- The new-generation SLK: More powerful, more economical, more intense
- 7g-Tronic ECU Repair
- "7G-Tronic: Mercedes-Benz presents the world's first seven-speed automatic transmission for passenger cars" (PDF). DaimlerChrysler press release. Retrieved 14 October 2008.