Transmission – Overview

Design and Function

Applies to: 2004–2010; M56

The transmission and final drive are constructed together in a common housing made of aluminum. The unique design of the transmission makes it extremely compact, yet capable of transferring high torque.

The transmission and engine have shock absorbent mountings on the side members.

The gear controls consist of the gear selector assembly, the gear selector lever with associated link arms and two mechanical shift cables which are connected to a lever each on the transmission.

The movements of the gear selector lever are transferred to the transmission via two heavy duty mechanical cables. This requires limited force for gear shifts and ensures that each gear selection is distinct. Vibration and other movement from the transmission is not felt through the gear selector lever.

The gear selector assembly is seated on rubber bushings secured to the floor of the tunnel for efficient sound insulation.

The bearings for the gear selector lever in the gear selector assembly and the bearings for the outer mechanical cable controls are permanently lubricated low friction bearings.

The transmission housing has only one seal surface. The seal is a liquid gasket.

The transmission and final drive are extremely compact. The oil is synthetic and does not normally need to be changed. For further information about oil and oil capacity, see Specifications, transmission fluid.

The hole in the level plug is used to top up the oil and check its level. The oil is drained through the drain plug.

The left-hand drive shaft is secured to the final drive by a snap ring. This requires a special tool for removal.

Applies to: 2004–2010; MMT6

MMT6 is a manual transmission based on a 3 shaft design with one input and two output shafts.

MMT6 stands for:

• Modular
• Manual
• Transmission
• 6-shift.

The transmission is intended to be part of a transverse drive line with front wheel drive. The transmission and final drive are constructed together in a common housing made of aluminum. The unique design of the transmission and final drive makes it extremely compact, yet capable of transferring high torque.

The transmission and engine have shock absorbent mountings on the side members with pendulum suspension.

The gear controls consist of the gear selector assembly, the gear selector lever with associated control arms and two mechanical gear shift cables (mechanical transmission cable for lateral travel and mechanical shift cable) which are connected to a lever each on the transmission. The mechanical transmission cable for lateral travel is adjustable. If there is a fault in, or damage to, one of the mechanical cables, both must be replaced at the same time.

The gear selector assembly is seated in rubber bushings secured to the floor of the tunnel for efficient sound insulation. The bearings for the gear selector lever in the gear selector assembly and the bearings for the outer mechanical cable controls are permanently lubricated low friction bearings.

The transmission fluid is synthetic and does not normally need to be changed. The oil is heat resistant and tolerates high loads. Fluid is topped up via the oil filler pipe. The fluid is checked via the level plug. The fluid is drained through the drain plug in the base of the transmission.

The left-hand drive shaft is secured to the final drive by a snap ring. This requires a special tool for removal.

Applies to: 2004–2012; AW50/51 AWD, AW55-50/51SN

AW55-51 is a 5 speed electronically controlled automatic transmission with a lock-up function for the three highest gears. The transmission control module (TCM) adapts the gear changes to ensure that the correct gear is selected for the driving mode, engine load, driver requirements, speed etc. This gives good fuel economy combined with increased comfort by ensuring smoother gear changes and lower noise levels.

In a vehicle with an automatic transmission, the driver neither needs to decide which gear should be used nor shift gear. There is a operating system in the AW55-51 which uses a torque converter and gear shift system to do this.

For information about the transmission control module (TCM) and its functions, see Design and Function, transmission control module (TCM).

Applies to: 2004–2012; M66, M66 AWD

The transmission is intended to be part of a transverse drive line with front wheel or four wheel drive. The transmission and final drive are constructed together in a common housing made of aluminum. The unique design of the transmission and final drive makes it extremely compact, yet capable of transferring high torque.

The engine and transmission have damped mountings, either on the side members with pendulum mounting or on a sub frame.

The gear controls consist of the gear selector assembly, electronic back-up (reverse) inhibitor and two mechanical shift cables which are connected to a lever each on the transmission. The gear selector is not adjustable. However lateral movement can be adjusted. If there is a fault or damage in/to one of the mechanical cables, both must be replaced at the same time.

The gear selector assembly is seated in rubber bushings secured to the floor of the tunnel for efficient sound insulation. The bearings for the gear selector lever in the gear selector assembly and the bearings for the outer mechanical cable controls are permanently lubricated low friction bearings.

The oil is synthetic.

Applies to: 2005–2012; MTX75

MTX-75 is a 5-speed manual transmission. The transmission and final drive are integrated in the same housing, made of aluminum. MTX-75 has two shafts:

• input shaft
• output shaft.

MTX-75 means:

• M: Manual
• T: Transmission
• X: Transaxle (Transverse engine, front-wheel drive)
• 75: Distance between input and output shaft in mm.

The transmission and engine have shock absorbent mountings on the side members.

The gear controls consist of the gear selector assembly, the gear selector lever with associated link arms and two mechanical shift cables which are connected to a lever each on the transmission.

The movements of the gear selector lever are transferred to the transmission via two heavy duty mechanical cables. This requires limited force for gear shifts and ensures that each gear selection is distinct. Vibration and other movement from the transmission is not felt through the gear selector lever.

The gear selector assembly is seated on rubber bushings secured to the floor of the tunnel for efficient sound insulation.

The bearings for the gear selector lever in the gear selector assembly and the bearings for the outer mechanical cable controls are permanently lubricated low friction bearings.

The transmission housing has three sealing surfaces, the sealing consists of liquid gaskets.

The transmission fluid is synthetic and does not normally need to be changed.

The left-hand drive shaft is secured to the final drive by a snap ring. This requires a special tool for removal.

Applies to: 2008–2012; MPS6

This Design and Function describes the transmission's mechanical parts.

The transmission is a 6-speed electronically controlled transmission, so-called Powershift. It has the same function as an automatic transmission but is more similar to a manual transmission.

The transmission is of a design with three shafts and two clutches (wet double clutch) but no clutch pedal. Electronics and hydraulics control the clutches just like in a conventional automatic transmission.

The transmission features a split (divided) input shaft with a clutch each. The clutches work independently of each other.

The transmission has 4 gearshift forks which are controlled by the Transmission control module (TCM) via solenoids. Electronics and hydraulics control the clutches via the Transmission control module (TCM) or via manual shifting in the same way as in a conventional automatic transmission. In case of manual shifting, the driver handles gearshifting.

The gears are pre-selected, that is, one clutch makes sures that the current gear ends up in the correct position at the same time as the other clutch prepares the next gear. This set-up means that the power transfer from the engine to the transmission is not interrupted when shifting.

Shifting takes place under load, thus a permanent power transfer can be maintained, which is the meaning of Powershift.

The gearshift lever is of the same type as for conventional automatic transmissions and has positions P, R, N, D, and M.

The transmission fluid is a high-quality synthetic oil which is unique for this type of transmission. For transmission oil change interval, see Service program.

The transmission is intended to be a part of a transverse drivetrain with front-wheel drive. The transmission weighs 91 kg with oil and has a maximum torque of 450 Nm.

The Transmission control module (TCM), solenoids, and sensors are integrated in the transmission. For more information on Transmission control module (TCM), its function and associated sensors, see Design and Function, Transmission control module (TCM).

Applies to: 2011–2012; B6

General

Manual transmission B6 is a 6-speed transmission. The design has been made very compact and with low weight.

The transmission consists of two parts, clutch housing and transmission housing.

The gearshift mechanism consists of 3 shafts where reverse gear is located on a shorter shaft and the other gears are located on the two longer shafts.

The 3 gear shafts are carried in spherical roller bearings while the final drive is carried in tapered roller bearings.

The wire system that transmits the gearshift lever's movements is, like the internal gear selector control, a similar solution to transmission MMT6.

Specifications

Applies to: 2011–2012; TF-80SC

Automatic transmission TF80SC Generation 2

This transmission has been updated on several points to meet high demands for fuel economy and comfort. TF80SC Gen 2 replaces earlier versions of TF80SC.

Changes compared to earlier version:

• Solenoids
• tapered bearings
• friction pads
• Seals
• oil with lower viscosity
• "lock-up" at lower engine rpm
• software in TCM (Transmission Control Module)
• fastening AC bracket (6-cyl. engines)

These changes contribute to lower internal losses and, together with upshifting at lower engine rpms, faster downshifts, the result is lower fuel consumption, better shifting quality, and higher efficiency.

TF-80SC (TF-80SC AWD) is an electronically controlled 6-speed automatic transmission with Geartronic.

The Geartronic function combines two transmissions in one. One adaptive 6-gear automatic transmission which enables relaxed driving, and a "manually" shifted transmission which enables more active driving with manual shifting. In case of manual shifting, the gear selector is pushed forward to upshift to a higher gear and it's pulled back to downshift to a lower gear. However, in certain situations the Transmission control module (TCM) assumes the gearshifting decisions. For more information about shifting with Geartronic, see Design and Function, Transmission control module (TCM).

TF-80SC has a lock-up-function on all forward gears except 1st gear. The torque converter has a locked and slipping lock-up-function.

Gearshifts are controlled by an hydraulic operating system. Gearshifts take place without freewheeling and completely automatically in terms of load and speed.

TF-80SC has two planetary train units, a front and a rear, whose shifts are controlled by a number of clutches and brakes. The rear planetary train is of the Ravigneaux type.

The oil level is checked by level pipe (the transmission does not have a conventional dipstick).

The transmission has a total of 8 solenoids that control the hydraulic flow. 6 of these solenoids control the shift process, 1 solenoid controls the torque converter's lock-up function and 1 solenoid controls the system pressure.

The gear selector sensor is integrated in the Transmission control module (TCM). The Transmission control module (TCM) is integrated in the transmission. For information about the Transmission control module (TCM), solenoids and sensors, see Design and function, Transmission control module (TCM).