Self-Study Programme 457 Audi A8 '10 power transmission.pdf

Self-Study Programme 457

Audi A8 ’10 Power Transmission

Eight-speed Automatic Gearboxes 0BK and 0BL

Rear Axle Drives 0BF and 0BE – Sport Differential

Audi

Service Training

The world of Audi gearboxes

With the innovative new developments in the field of power trans-

mission, such as the multitronic gearbox and the dual-clutch gear-

box, Volkswagen and Audi have radically revised the requirements

profile for modern multistep automatic gearboxes.

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 auto-

matic 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.

In addition to better fuel economy, now a major issue in view of

the ongoing debate on CO 2 emissions, both dynamics and respon-

siveness 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 gear-

box).

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

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.

These development efforts are reflected in the new eight-speed

automatic gearboxes 0BK and 0BL.

"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

The higher fuel efficiency of the 8HP automatic gearbox genera-

tion 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

- 6 %

- 2 %

- 5 %

- 3 %

- 6 %

- 5 % 1)

Three-speed

Four-speed

Five-speed

First-genera-

tion six-speed

Second-genera-

tion six-speed

Eight-speed

457_006

Improving the fuel efficiency of ZF automatic gearboxes

457_007

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.

1) Potential fuel savings in start-stop mode as determined in

NEDC simulations (New European Driving Cycle)

Contents

Power transmission in the Audi A8 ’10

New features at a glance __________________________________________________________________________________________________________________________ 6

shift-by-wire shift control system

Introduction ________________________________________________________________________________________________________________________________________ 8

tiptronic function ___________________________________________________________________________________________________________________________________ 8

Features of the shift control system _____________________________________________________________________________________________________________ 9

Operating concept_________________________________________________________________________________________________________________________________ 10

Shift schematic – function ________________________________________________________________________________________________________________________ 11

Selector lever sensors control unit J587 ________________________________________________________________________________________________________ 12

Selector lever position sensor G727_____________________________________________________________________________________________________________ 12

Functions, networking and interfaces ___________________________________________________________________________________________________________ 13

Gear knob/selector lever release button E681 _________________________________________________________________________________________________ 14

Selector lever position indicator unit Y26 ______________________________________________________________________________________________________ 14

Function diagram – selector lever E313_________________________________________________________________________________________________________ 15

Gearshift indicators _______________________________________________________________________________________________________________________________ 15

shift-by-wire functions/operation _______________________________________________________________________________________________________________ 16

Auto P function (automatic parking lock)_______________________________________________________________________________________________________ 16

Emergency release device for the parking lock _________________________________________________________________________________________________ 18

Eight-speed automatic gearbox 0BK/0BL

Introduction _______________________________________________________________________________________________________________________________________ 20

Specifications ______________________________________________________________________________________________________________________________________ 21

Special and common features at a glance ______________________________________________________________________________________________________ 22

Splined prop shaft_________________________________________________________________________________________________________________________________ 23

Centre differential_________________________________________________________________________________________________________________________________ 23

Torque converter __________________________________________________________________________________________________________________________________ 24

ATF supply/ATF pump_____________________________________________________________________________________________________________________________ 25

ATF (Automatic Transmission Fluid)_____________________________________________________________________________________________________________ 25

Planetary gearbox _________________________________________________________________________________________________________________________________ 26

Shift elements _____________________________________________________________________________________________________________________________________ 26

Brakes ______________________________________________________________________________________________________________________________________________ 27

Clutches ____________________________________________________________________________________________________________________________________________ 27

Shift schematic/shift matrix _____________________________________________________________________________________________________________________ 28

Description of gears – torque characteristic ____________________________________________________________________________________________________ 29

Sectional view of 0BK gearbox ___________________________________________________________________________________________________________________ 32

Oil system/lubrication/sealing of 0BK gearbox ________________________________________________________________________________________________ 34

Separate oil systems ______________________________________________________________________________________________________________________________ 34

Common oil system _______________________________________________________________________________________________________________________________ 35

Oil system/lubrication/sealing of 0BL gearbox ________________________________________________________________________________________________ 36

Gear oil system (common oil system) ___________________________________________________________________________________________________________ 36

Common oil system – gear oil circuit ____________________________________________________________________________________________________________ 37

Innovative Thermal Management (ITM) ________________________________________________________________________________________________________ 38

Gearbox heating/cooling – V8 FSI engine_______________________________________________________________________________________________________ 38

Gearbox heating/cooling – V8 TDI engine ______________________________________________________________________________________________________ 40

Mechatronics – electro-hydraulic control system ______________________________________________________________________________________________ 42

Mechatronics/automatic gearbox control unit J217___________________________________________________________________________________________ 43

Mechatronics – actuators _________________________________________________________________________________________________________________________ 44

Pressure regulating valves – solenoid valves ___________________________________________________________________________________________________ 44

Hydraulic interfaces _______________________________________________________________________________________________________________________________ 45

Monitoring of temperature in J217______________________________________________________________________________________________________________ 46

Mechatronics – sensors ___________________________________________________________________________________________________________________________ 47

Gearbox input speed sender G182_______________________________________________________________________________________________________________ 47

Gearbox output speed sender G195 _____________________________________________________________________________________________________________ 47

Parking lock ________________________________________________________________________________________________________________________________________ 48

Parking lock – function ____________________________________________________________________________________________________________________________ 48

Parking lock – limp-home functions _____________________________________________________________________________________________________________ 50

Parking lock sender G747 ________________________________________________________________________________________________________________________ 51

Functions – neutral idle __________________________________________________________________________________________________________________________ 52

Functions – gearbox adaption ___________________________________________________________________________________________________________________ 53

Functions – start-stop system ___________________________________________________________________________________________________________________ 54

Hydraulic Impulse Storage – HIS ________________________________________________________________________________________________________________ 54

Start-stop mode __________________________________________________________________________________________________________________________________ 56

Functions – navigation-based gear selection___________________________________________________________________________________________________ 58

Functions – displays/warnings___________________________________________________________________________________________________________________ 62

Functions – special feature of adaptive cruise control (ACC) mode __________________________________________________________________________ 63

Functions – encoding the automatic gearbox control unit J217 _____________________________________________________________________________ 63

Functions – adapting the gear indicator ________________________________________________________________________________________________________ 63

Functions – limp-home programs and substitute programs _________________________________________________________________________________ 63

Towing _____________________________________________________________________________________________________________________________________________ 63

Rear axle drive 0BC/0BF/0BE

Conventional rear axle drive/sport differential _______________________________________________________________________________________________ 64

Rear axle drive 0BE/sport differential __________________________________________________________________________________________________________ 65

Intelligent torque distribution __________________________________________________________________________________________________________________ 66

Self-Study Programmes relevant to the Audi A8 ’10__________________________________________________________________________________________ 67

457_102

Eight-speed automatic gearboxes 0BK and 0BL belong to the category of conventional multistep torque converter automatic gearboxes.

They have many design and functional features in common with the six-speed automatic gearboxes described in Self-Study Programmes

283, 284 and 385.

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.

Note

Reference

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