Self Study Program 457 – Audi A8 2010 Power Transmission Eight-speed Automatic Gearboxes 0BK and 0BL Rear Axle Drives 0BF and 0BE – Sport Differential
VAG SSP 457. With the innovative new developments in the field of power transmission, such as the multitronic gearbox and the dual-clutch gearbox, Volkswagen and Audi have radically revised the requirements profile for modern multistep automatic gearboxes.
In addition to better fuel economy, now a major issue in view of the ongoing debate on CO2 emissions, both dynamics and responsiveness top the list of requirements for sporty premium vehicles. These demands have already been satisfied with the launch of the second-generation six-speed automatic gearboxes by ZF Getriebe GmbH (refer to Self-Study Programme 385 covering the 0B6 gearbox).
Vibration damping has been improved with the help of new torque converters, giving better fuel economy and a more direct driving feel. Thanks to neutral idle control, which reduces torque input when the vehicle is stationary with the foot brake applied, and a marked reduction in shift and reaction times, the user-friendly automatic torque converters have evolved into modern, highly efficient sport gearboxes.
“When developing the new automatic gearbox we did not focus on the number of gears, but on markedly improved fuel economy and enhanced performance.”
Dr. Michael Paul,
Board Member with responsibility for Technology,
ZF Friedrichshafen AG
A detailed system analysis carried out by ZF Getriebe GmbH has shown that the ever-growing list of customer wishes can no longer be satisfied by further enhancement of the existing six-speed automatic gearboxes. For this reason, a gearbox series based on an entirely new gearbox concept has been developed for the new Audi A8 ’10 in collaboration with ZF Getriebe GmbH.
The main focus of development was on:
- better fuel economy with reduced RPM and drag losses
- improved performance with shorter gear steps, multiple direct shifts and a low power-to-weight ratio
- design flexibility in the interior through the use of a shift-by-wire concept
These development efforts are reflected in the new eight-speed automatic gearboxes 0BK and 0BL.
The higher fuel efficiency of the 8HP automatic gearbox generation is due to the following modifications:
- a wider ratio spread and more gears for better adaptation to ideal engine operating points
- significantly reduced drag torque in the shift elements (only two open shift elements per gear)
- use of a more efficient ATF pump (twin-stroke vane pump)
- improved torsion damping in the converter
Another potentially effective way of improving fuel efficiency is to eliminate idling fuel consumption in the internal combustion engine while the vehicle is at a standstill. This has a very positive impact in city traffic.
To exploit this potential, the 3.0 V6 TDI uses the start-stop function in combination with an automatic gearbox for the first time. Other applications are currently being developed.
- Power transmission in the Audi A8 ’10
- New features at a glance
- shift-by-wire shift control system
- tiptronic function
- Features of the shift control system
- Operating concept
- Shift schematic – function
- Selector lever sensors control unit J587
- Selector lever position sensor G727
- Functions, networking and interfaces
- Gear knob/selector lever release button E681
- Selector lever position indicator unit Y26
- Function diagram – selector lever E313
- Gearshift indicators
- shift-by-wire functions/operation
- Auto P function (automatic parking lock)
- Emergency release device for the parking lock
- Eight-speed automatic gearbox 0BK/0BL
- Special and common features at a glance
- Splined prop shaft
- Centre differential
- Torque converter
- ATF supply/ATF pump
- ATF (Automatic Transmission Fluid)
- Planetary gearbox
- Shift elements
- Shift schematic/shift matrix
- Description of gears – torque characteristic
- Sectional view of 0BK gearbox
- Oil system/lubrication/sealing of 0BK gearbox
- Separate oil systems
- Common oil system
- Oil system/lubrication/sealing of 0BL gearbox
- Gear oil system (common oil system)
- Common oil system – gear oil circuit
- Innovative Thermal Management (ITM)
- Gearbox heating/cooling – V8 FSI engine
- Gearbox heating/cooling – V8 TDI engine
- Mechatronics – electro-hydraulic control system
- Mechatronics/automatic gearbox control unit J217
- Mechatronics – actuators
- Pressure regulating valves – solenoid valves
- Hydraulic interfaces
- Monitoring of temperature in J217
- Mechatronics – sensors
- Gearbox input speed sender G182
- Gearbox output speed sender G195
- Parking lock
- Parking lock – function
- Parking lock – limp-home functions
- Parking lock sender G747
- Functions – neutral idle
- Functions – gearbox adaption
- Functions – start-stop system
- Hydraulic Impulse Storage – HIS
- Start-stop mode
- Functions – navigation-based gear selection
- Functions – displays/warnings
- Functions – special feature of adaptive cruise control (ACC) mode
- Functions – encoding the automatic gearbox control unit J217
- Functions – adapting the gear indicator
- Functions – limp-home programs and substitute programs
- Rear axle drive 0BC/0BF/0BE
- Conventional rear axle drive/sport differential
- Rear axle drive 0BE/sport differential
- Intelligent torque distribution
- Self-Study Programmes relevant to the Audi A8 ’10
Eight-speed automatic gearboxes 0BK and 0BL belong to the category of conventional multistep torque converter automatic gearboxes.
These SSPs represent, as it were, the basis for SSP 457. Hence where the technology is identical, reference is made to SSPs 283, 284 and 385. It is, therefore, advisable to have all three booklets ready to hand.
The Self-Study Programme teaches the basics of the design and function of new models, automotive components or technologies.
It is not a Repair Manual. Figures given are for guidance purposes only and refer to the software version valid at the time of preparation of the SSP.
For further information about maintenance and repair work, always refer to the current technical literature.