The 2019 Audi A8 Running Gear and Suspension
Systems
eSelf-Study Program 960293

Audi of America, LLC
Service Training
Created in the U.S.A.
Created 5/2018
Course Number 960293

©2018 Audi of America, LLC
All rights reserved. Information contained in this manual is based on
the latest information available at the time of printing and is subject to
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Always check Technical Bulletins and the latest electronic service repair
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in this booklet.

Revision: May 29, 2018
ii

Introduction

1

Axles

2

Front axle
Rear axle
Wheel alignment and adjustment

2
3
4

Steering system

5

Overview
System components

5
5

Dynamic all-wheel steering

6

Overview
Basic function
Programs for particular driving situations
Operation and warning/indicator lamps
System response to faults
Service

6
9
11
12
12
13

Brake system

14

Brake system, front axle
Brake system, rear axle
Brake servo
Electromechanical parking brake (EPB)
ESC

14
14
15
15
16

Adaptive air suspension

18

Overview
Air supply
Air spring strut, front axle
Air spring strut, rear axle
Accumulator
Vehicle level sensors
System response to faults
Service

18
19
20
20
20
20
22
22

Knowledge assessment

The eSelf-Study Program (eSSP) teaches a basic understanding of the design and mode of operation of new models, new
automotive components or new technologies.

23

Note

It is not a repair manual! Figures are given for explanatory purposes only and refer to the data valid at the time of
preparation of the SSP.
For further information about maintenance and repair work, always refer to the current technical literature.

Reference
iii

iv

Introduction
The suspension of the 2019 A8 has been designed with new
technologies and control systems to achieve even greater
levels of comfort, driving dynamics and safety. Air suspension
with dynamic control is standard. The front and rear axles of
each consist of a responsive high precision five-link construction made in large part out of aluminum.

The brake system offers substantial performance reserves for
any driving situation.

Progressive steering (included as standard equipment)
reduces the amount of steering effort required. Optional
dynamic steering is combined with rear wheel steering for the
first time for Audi in the 2019 A8. This system enhances
certain essential subjective and objective dynamic characteristics of the driving experience.

A wide range of steering wheels, wheels and tires is available
for further customization. With the Audi A8, ACC is included
for the first time in the new driver assist system “adaptive
cruise assist”.

A ceramic brake system is available as optional equipment.
The 9th generation ESC system provides high-performance
stability control for the vehicle.

663_001

All Audi A8 vehicles are equipped exclusively with running gear versions with quattro four-wheel drive.
The following suspension version is available:
›› Air suspension and damping control (adaptive air suspension, 1BK)
This version is standard equipment.

1

Axles
Front axle
The front axle is constructed according to the well-established five-link axle design, with particular emphasis on
light-weight construction. All fundamental components are
constructed from aluminum.

Upper wishbone
›› Forged aluminum components
›› Adopted from the 2018 Q5

Subframe
›› Three-part aluminum construction comprising a
cross member (extrusion) and two node castings

Wheel bearing housing
›› Forged aluminum components
›› New design
Air spring/damper
›› Forged aluminum component
›› New part

Anti-roll bar link rod
›› Aluminum component
›› Adopted from
2017 Audi Q7
Swivel joint
›› Adopted from
2017 Audi Q7
›› Aluminum housing

663_002

Shock absorber fork
›› Aluminum component
(cast-forged)
›› Adopted from
2017 Audi Q7

2

Anti-roll bar
›› Thin-walled tubular anti-roll bar
›› New part
›› Aluminum anti-roll bar
clamps, adopted from
2017 Audi Q7

Wheel bearing/wheel hub
›› Second generation wheel
bearing
›› Adopted from
2017 Audi A4/2018 Q5

Track control links and guide links
›› Forged aluminum components
›› Adopted from
2017 Audi Q7

Rear axle
The rear suspension of the 2019 A8 is a newly developed
five-link axle.
The geometric layout of the suspension links provides a clear
separation in the absorption of longitudinal and lateral
forces. Elastomer bushings with a mixture of high-damping
materials and integrated spacer sleeves allow for a high
degree of radial stiffness with a low roll rate.

The use of subframe bushings with hydraulic damping
ensures that the axle is well-isolated from the vehicle body.
The wheel bearings have been optimized to reduce friction,
which helps to decrease rolling resistance.
Rear wheel steering is available as part of the optional
all-wheel steering.

Track rod
›› Forged aluminum component
›› New part

Lower wishbone (rear)
›› Aluminum
›› New part

Upper wishbone (rear)
›› Steel/forged aluminum component
›› New part/adopted from 2017 Q7

Air spring/damper
›› Forged aluminum component
›› New part

Hub carrier
›› Forged aluminum
component
›› New part
Coupling rod
›› Forged aluminum component
›› New part
Wheel bearing/
wheel hub
›› 3rd generation
›› New part

663_003

Upper wishbone (front)
›› Forged aluminum
component
›› New part

Subframe
›› Aluminum
›› New part

Lower wishbone (front)
›› Sheet-steel part
›› New part

Anti-roll bar
›› Forged aluminum component
›› New part

3

Wheel alignment and adjustment

Toe setting at attachment point
of track control link to subframe
(not shown in illustration)

Camber setting at attachment point
of spring link to subframe
(covered by aerodynamic faring)

Cam

ber b

alan

cing

Toe setting

4

663_004

Steering system
Overview
The steering system of the 2019 A8 is the same electromechanical power steering used in the 2017 Q7. Electrical
steering column adjustment is standard equipment.
The optional dynamic all-wheel steering system includes
rear wheel steering.

System components
Electromechanical power steering
The electrical power steering (EPS) system of the A8 has
the same layout and functionality as the system used in the
2017 Q7. The service procedures are the also the same.
Power Steering Control Module J500 communicates via
FlexRay channel A.

663_005

Progressive steering is included as standard equipment.

Steering column
663_006

All A8 models are equipped with an electrically adjustable
steering column. It can be adjusted approximately 2.3 in
(60 mm) horizontally and 1.9 in (50 mm) vertically. Power
Steering Control Module J500 and both adjustment motors
are attached directly to the steering column.
In the event of a crash, the column moves relative to the
column tube. This is possible because of the nested tube
construction. The maximum distance of travel is approximately 3.1 in (80 mm).
On vehicles with dynamic all-wheel steering, the steering
column is shorter because the actuator for the dynamic
steering is attached at the bottom end of the steering
column.

663_007

Steering wheels
The available steering wheels have a four-spoke design and
a total diameter of 14.7 in (375 mm). The standard equipment version has a plastic airbag cover. Multifunction
switches are installed on all steering wheel versions. All of
the steering wheels offered as optional equipment feature
aluminum tiptronic levers. Steering wheel heating and
different steering wheel colors are available as optional
extras.

663_008

5

Dynamic all-wheel steering
Overview
The dynamic all-wheel steering system of the A8 is a further
development of the system introduced on the 2017 Q7.
All-wheel steering makes it possible for the wheels of the
front and rear axles to achieve defined steering angles
independently. This improves fundamental subjective and
objective aspects of the vehicle’s dynamic characteristics
such as:
›› A smaller turning radius.

663_009

›› Less effort required for steering.
›› Significantly improved agility, particularly at slow and
moderate speeds.
›› Improved driving stability, particularly when changing
lanes or swerving to avoid obstacles.
›› Improved responsiveness and decreased vehicle reaction
times.
The components and construction of the dynamic steering
are the same as those of the second generation dynamic
steering used in the 2017 Audi A4. Active Steering Control
Module J792 communicates via FlexRay channel A.
The components and construction of the rear wheel steering
are the same as those of the 2017 Q7. However, the actuator is smaller and the its installation position has been
rotated. Rear Axle Steering Control Module J1019 also
communicates via FlexRay channel A.
Vehicles with conventional steering systems require a
degree of compromise with regard to steering ratio and
driving stability.

Dynamic steering actuator

663_010

As a general rule, a low steering ratio, combined with a
decreased amount of effort required for steering, makes the
steering feel very direct. The driver feels distinctly how movements in the steering wheel correspond directly to changes in
driving direction. Vehicle handling is dynamic and agile.
With regard to driving stability, very direct vehicles that are
not equipped with dynamic all-wheel steering are given to
“nervous” handling in certain driving situations. When
driving straight ahead at high speeds, even small movements in the steering wheel, for example, may translate
into significant reactions which can de-stabilize the vehicle.

Rear axle steering unit

663_011

The wheelbase also has a significant influence on driving
stability. Vehicles with a longer wheelbase display a high
degree of stability, while those with a shorter wheelbase
range from agile to unstable.

Note
For further information on the dynamic steering and rear wheel steering systems, please refer to eSelf-Study Program
960163, The 2017 Audi Q7 Running Gear and Suspension System and eSelf-Study Program 990263, The 2017 A4 Introduction.
6

Dynamic all-wheel steering makes it possible to reconcile
the conflict between a direct steering ratio and driving
stability when necessary.

ΔR

Wheelbase 2

Wheelbase 1

The steering ratio/directness and wheelbase are therefore
two criteria in the design of the steering system which
must be considered because they interact with one another.
Combining a direct steering ratio with a short wheelbase
results in a highly agile but potentially unstable vehicle.
Agility is an advantage when maneuvering into or out of a
parking space, and at low speeds on roads with lots of
bends. At high speeds however, the vehicle quickly becomes
unstable, so that the average driver may find it difficult to
maintain control.

Radius R
663_012

The diagram shows an example of this relationship. The
black outlines of the wheels illustrate conventional steering. The dynamic steering allows the front axle to achieve a
steering angle that is greater than the driver’s steering
input. At the same time, the wheels on the rear axle are
turned in the same direction.

Direct

Effective range of dynamic all-wheel steering

Steering wheel angle

Stable

Virtual increase
in wheelbase
length

Unstable (agile)

Indirect

Wheelbase

The turning radius remains the same in this example,
meaning that the directness of the vehicle is unchanged.
However, the virtual increase in the length of the wheelbase significantly increases the driving stability.

Reduction of
turning radius

Turning radius
663_013

7

With dynamic all-wheel steering, the required steering
angle at the front and rear axles is specified by Drivetrain
Control Module J775. The specified steering angle is converted into the actual electrical current requirements for
the actuators at the front and rear axles by Power Steering
Control Module J500, Rear Axle Steering Control Module