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 Mercedes-Benz 5G-Tronic transmission 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 transmission is built at the Mercedes-Benz Stuttgart-Untertuerkheim plant in Germany, the site of Daimler-Benz's original production facility.
The 7G-Tronic is currently available on the SsangYong Chairman W, SsangYong Rexton W, and SsangYong New Rodius/Korando Turismo (in South Korea)/Turismo (in UK).
In July 2009, Mercedes-Benz announced they are working on a new nine-speed automatic.
Video Mercedes-Benz 7G-Tronic transmission
AMG SpeedShift MCT
Mercedes-AMG developed the 7-speed MCT "Multi Clutch Technology" planetary semi-automatic transmission.
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.
It is available on the 2009 SL 63 AMG and E63 AMG, and will be used for the 2011 S63 AMG and CL63 AMG, and the 2012 CLS63 AMG and C63 AMG.
Maps Mercedes-Benz 7G-Tronic transmission
Specifications
Gear ratios
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 problems there are existing two options. The first one consist of installing a new control unit (Mercedes-Benz dealer have to do programming of electronic). The second solution is repairing of the damaged electronic (no programming or coding by Mercedes-Benz)
See also
- List of Daimler AG transmissions
References
External links
- 7g-Tronic ECU Repair
- GermanCarFans
- "7G-Tronic: Mercedes-Benz presents the world's first seven-speed automatic transmission for passenger cars" (PDF). DaimlerChrysler press release. Retrieved 14 October 2008.
Source of the article : Wikipedia
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