engine AUDI A6 ALLROAD 1999 C5 / 2.G Pneumatic Suspension System

10
The degree of damping of the vibration
damper has no signiÞcant inßuence on the
value of the natural frequency of the
bodywork. It inßuences only how quickly the
vibrations cease (damping coefÞcient). For
further information, see chapter ÒVibration
dampingÓ.
Matching of the natural frequency of the
bodywork
The axle loads (sprung masses) of a vehicle
vary, at times considerably, depending on the
engine and equipment installed.
To ensure that the bodywork height
(appearance) and the natural frequency of the
bodywork (which determines the driving
dynamics) remains practically identical for all
vehicle versions, different spring and shock
absorber combinations are Þtted to the front
and rear axles in accordance with the axle
load.
For instance, the natural frequency of the
bodywork of the Audi A6 is matched to 1.13Hz
on the front axle and 1.33Hz on the rear axle
(design position).
The spring rate of the springs therefore
determines the value of the natural frequency
of the bodywork.
The springs are colour-coded to differentiate
between the different spring rates (see table).
Principles
For standard running gear without self-
levelling, the rear axle is always
matched to a higher natural frequency
of the bodywork because when the
vehicle is loaded, it is principally the
load to the rear axle which increases,
thus reducing the natural frequency of
the bodywork.
242_073
Vehicle height Natural frequency of the bodyworkComponent tolerance band
Natural frequency tolerance band Usable load range
of a spring
Height tolerance
Axle load 800 kg 850 kg 900 kg 950 kg 1.13 Hz
c

F1

= 33.3 N/mmc

F2

= 35.2 N/mmc

F3

= 37.2 N/mmc

F4

= 39.3 N/mmc

F5

= 41.5 N/mmc

F6

= 43.7 N/mm

Spring rate levels of the front axle for the A6

11
OJL1BA
OYF

Spring allocation table (e.g. A6 front axle 1BA)
PR-No. weight
class, front axleAxle load (kg) Suspension, left and right
(spring rate)Colour coding
Standard
running
gear
e.g. 1 BAOJD 739 - 766 800 411 105 AN (29.6 N/mm) 1 violet, 3 brown
OJE 767 - 794 800 411 105 AP (31.4 N/mm) 1 white, 1 brown
OJF 795 - 823 800 411 105 AQ (33.3 N/mm) 1 white, 2 brown
OJG 824 - 853 800 411 105 AR (35.2 N/mm) 1 white, 3 brown
OJH 854 - 885 800 411 105 AS (37.2 N/mm) 1 yellow, 1 brown
OJJ 886 - 918 800 411 105 AT (39.3 N/mm) 1 yellow, 2 brown
OJK 919 - 952 800 411 105 BA (41.5 N/mm) 1 yellow, 3 brown
OJL 953 - 986 800 411 105 BM (43.7 N/mm) 1 green, 1 brown
OJM 987 - 1023 800 411 105 BN (46.1 N/mm) 1 green, 2 brown
Sports
running
gear
e.g. 1BEOJD 753 - 787 800 411 105 P (40.1 N/mm) 1 grey, 3 violet
OJE 788 - 823 800 411 105 Q (43.2 N/mm) 1 green, 1 violet
OJF 824 - 860 800 411 105 R (46.3 N/mm) 1 green, 2 violet
OJG 861 - 899 800 411 105 S (49.5 N/mm) 1 green, 3 violet
OJH 900 - 940 800 411 105 T (53.0 N/mm) 1 yellow, 1 violet
OJJ 941 - 982 800 411 105 AA (56.6 N/mm) 1 yellow, 2 violet
OJK 983 - 1027 800 411 105 AB (60.4 N/mm) 1 yellow, 3 violet
Weight class of
front axleRunning
gear
Weight class of
the rear axle
242_108
Proof of warranty
Vehicle data
Vehicle identiÞcation number
Type description
Engine capacity / gearbox / month/
year of manufacture
Engine code / gearbox
code letters
Paint no. / interior equipment no.
M-equipment number
Un-laden weight / consumption
Þgures / CO
2
emissionsDate of
Delivery
Stamp of the
Audi delivery
centre

39
¥ Environmentally friendly, uses air
¥ Good operating safety due to great
stability.
¥ Electronic control system with
comprehensive self-diagnosis functions
¥ Maintenance-free Along with the principle advantages of self-
levelling (see Principles), the system realised
in the A6 has the following advantages:
¥ Virtually load-independent suspension
and vibration behaviour.
¥ Little space requirement due to compact
design, especially in the axle area.
¥ Self-levelling even available when engine
is off.
¥ Rapid raising and lowering times
¥ Low energy requirement
Air springs with PDC damperSelf-levelling suspension, A6 quattro
drive
Air supply unit242_041