brake AUDI S8 2014 Repair Manual

Incorrect wheel alignment
Incorrect wheel alignment can cause exces­
sive tire wear, impairing the safety of the vehi­
cle. If tires show excessive wear, have the
wheel alignment checked by an authorized
Audi dealer or qualified workshop .
All Wheel Drive
Vehicles with quattro must always have tires
of the same size, construction and tread type. For details see ~page 204.
_& WARNING
Sudden tire failure can lead to loss of con­
trol, a crash and serious personal injury!
- Never drive a vehicle when the tread on
any tire is worn down to the wear indica­
tors.
- Worn tires are a safety hazard, they do
not grip well on wet roads and increase
your risk of "hydroplaning" and loss of
control.
- Always keep chemicals that can cause
tire damage, such as grease, oil, gasoline
and brake fluid away from tires.
- Tires age even if they are not being used
and can fail suddenly, especially at high
speeds . Tires that are more than 6 years
old can only be used in an emergency
and then with special care and at lower
speeds .
- Never mount used tires on your vehicle if
you are not sure of their "previous histo­
ry." Old used tires may have been dam­
aged even though the damage cannot be
seen that can lead to sudden tire failure
and toss of vehicle control. Tires and wheels 259
New tires and replacing tires and wheels
New tires and wheels have to be broken in
.
Fig. 212 Tire specificat ion codes on t he s idewall o f a
tire
No. Description
@ Passenger car tire (where applicable)
@ Nominal width of tire in millimeters
@ Ratio of height to width (aspect ratio)
© Radial
® Rim diameter code
® Load index and speed rating
0 U.S. DOT tire identification number
® Audi Original tire
® Sever snow conditions
@ Tire ply composition and materials
used
@ Maximum load rating
@ Treadwear, traction and temperature
grades
@ Maximum permissible inflation pres-
sure
The tires and rims are essential parts of the
vehicle's design . The tires and rims approved
by Audi are specialty matched to the charac­
teristics of the vehicle and can make a major .,.

26 2 T ire s and wheel s
Driving with different tires reduces vehi­
cle handling and can lead to a loss of
co ntrol.
- I f the spare tire is not the same as the
t ires that are mounted on the veh icle -
for example with winter tires - only use
the spare tire for a short period of time
and dr ive with extra care . Refit the nor­
ma l road wheel as soon as safely possi­
ble.
- Never drive faste r than the maximum
speed for which the tires on your veh icle
are rated because ti res that a re driven
faster than their rated speed can fail
sudden ly .
- Overloading t ires cause heat build- up,
sudden tire failure, including a blowout
and sudden deflation and loss of control.
- T emperature grades app ly to tires that
are properly inflated and not over o r un­
derinflated .
- For technical reasons it is not a lways
possible to use wheels from other
vehicles -in some cases not even wheels
from the same vehicle model.
- If you insta ll wheel trim discs on the ve­
hicle whee ls, make sure that the air f low
to the brakes is not blocked. Reduced air­
flow to the brakes can them to overheat, increasing stopping distances and caus­
ing a collision .
- Run flat t ires may on ly be used on
vehicles that were equ ipped w ith them
at the facto ry . The vehicle must have a
chassis des igned for run f lat t ires . Incor­
rect use of run flat tires can lead to vehi­
cle damage or acc idents. Check with an
au thorized Aud i dealer or ti re specia list
to see if your vehicle can be equipped
with run f lat tires. If run flat tires are
used, they must be installed on all four
wheels . Mix ing tire types is not permit­
ted .
(D Note
-For technica l reasons, it is not generally
possib le to use the whee l rims from oth- er veh
icles. This can hold true for wheels
of the same vehicle type.
- If the spare tire is d iffe rent from the
tires that yo u have mounted on your ve­
hicle (for example winter tires o r wide
profi le tires), then use the spare tire for a
short period of time only and drive w ith
extra care. Replace the flat tire w ith the
tire matching the others on your vehicle as soon as possible .
- Never drive without the valve stem cap .
T he valves could get damaged .
® For the sake of the environment
Dispose of o ld tires in accordance with the
l ocal requirements.
Uniform tire quality grading
- Tread wear
- Traction AA A B C
- Temperature ABC
Quality grades can be found where applicab le
on the t ire s ide wall between tread shou lder
and maximum section width
c> page 259,
fig. 212 .
For example : Tread wear 200, Traction AA,
Temperature A.
All passenger ca r tires must conform to Feder­
al Safety Requirements in addition to these
grades.
Tread wear
T he tread wear grade is a comparative rating
based on the wear rate of the t ire when tested
u nder contro lled conditions o n a specified
government test course .
For example, a tire graded 1S0 would wear
one and o ne ha lf ( 11/2) times as well on the
gover nment course as a t ire g raded 100 .
The relative performance of tires depends upon the actual conditions of their use, how­
ever, and may depa rt s ignificantly from the
norm due to va ria tions in d riving hab its, se rv­
ice practices and differences in road character-
istics and climate.
ll-

chains because the vehicle will be ex­
tremely low. If you do drive with snow
chains on while the vehicle is at this lev­
el, the snow chains might severe ly dam­
age the wheelhouse and other parts of
the veh icle .
@ Tips
Where snow cha ins are mandatory oncer­
tain roads, this normally also applies to
veh icles with All Wheel Drive.
Wheel bolts
Wheel bolts mu st always be tigh tened to the
correc t torque .
The design of whee l bolts is matched to the
factory in sta lled r ims. If different rims are fit ­
ted, the correct wheel bolts with the right
length and correctly shaped bolt heads must
be used . This ensures that wheels are f itted
secure ly and that the brake system f unctions
correctly .
In certain circumstances, you may not use
wheel bolts from a d iffe rent vehicle -even if it
i s the same mode l
¢page 294.
A WARNING
Imprope rly tig hte ned or maintained whee l
bolts can be come loose causin g loss of
contro l, a co llision and serious persona l in­
jury .
- Alw ays keep the w heel bolts and the
th reads in the wheel hubs clea n so the
wheel bolts can turn easily and be prop­
er ly tightened .
- Never grease or oil the wheel bo lts and
the threads in the w heel h ubs. They can
become loose while driving if greased or
o iled, even if tightened to the specif ied
torque.
- Only use wheel bolts that belong to the rim being installed.
- Never use different whee ls bolts on your
vehicle .
- Always maintain the co rrect tightening
torq ue for the wheel bo lts to reduce the
Tire s an d wheel s 265
risk of a wheel loss. If the tighte ning tor­
que of t he wheel bolts is too low, they
can loosen and come out when the vehi­
cle is mov ing . If the tighte ning torque is
too h igh, the wheel bol ts and threads
can be damaged and the whee l can be­
come loose.
(I) Note
The specified torque for the whee l bolts is
90 ft lb ( 120 Nm) with a tole ranc e of± 7,4
ft lb(± 10 Nm). Torq ue whee l bolts diago­
nally. Afte r cha nging a whee l, the torq ue
must be checked as soon as possible wi th a
torque w rench -prefe rably by an au thor­
i z ed Audi dealer or qualif ied workshop .
Low aspect ratio tires
Your Audi is facto ry-eq uipped with low aspect
ratio tires. These tires have been thoro ughly
tested and been se lected specifically for your
model for their superb performance , road fee l
and handling under a variety of driving cond i­
tions . Ask your authorized Audi dealer for
more details.
The low aspect ratio of these t ires is ind icated
by a numeral of
55 or less in the tire's size
designation . The numera l rep resents the ratio
of the t ire's sidewall height in relation to its
t read width ex pressed in perce ntage. Conven ­
tion al tires have a he igh t/w idth ratio of 60 or
more.
The performance of low-aspe ct-ratio tire s is
particularly sensitiv e to improper infla tion
pres sure. It is therefore important that l ow
a spect ratio tires are inflated to the specified
pre ssure and that the inflation pressure is
regularly checked and maintained. Tire pres·
sures should be checked at least once a
month and always before a long trip
¢ page 254 , Checking tire pressure .
What you can do to avoid tire and rim
damage
Low aspect ratio tires can be damaged more
easily by impact w it h potholes , curbs, gul lies ..,.
•
•

272 What do I do now ?
Spare wheel
App lies to vehicles: with spare wheel
The spare wheel is stored in the wheel well
underneath the floor panel in the luggage
compartment.
Fig. 220 L uggage compartment: spare wheel
Taking out the spare wheel
.,. Lift the cargo floor by the plastic handle
¢fig. 220.
.. Hook the hand le into the luggage compart­
ment weather strip .
.. Turn the large screw¢
fig. 220 counter­
clockwise.
.. Take out the spare tire.
.. Always store the vehicle tool kit, the jack*
and the replaced tire in the luggage com­
partment ¢
page 141.
.,. Unhook the cargo floor before closing the
rear lid.
&_ WARNING
-
Loose items in the passenger compart ­
ment can cause serious personal injury
during hard braking or in an accident.
- Never store the spare wheel or jack and
tools in the passenger compartment.
(D Tips
Check the inflat ion pressure of the spare
tire periodically to keep the tire ready for
use.
Changing a wheel
Before changing a wheel
Observe the following precautions for your
own and your passenger's safety when chang­
ing a wheel.
.. After you experience a tire failure, pull the
car well away from moving traffic and try to
reach
level ground before you stop ¢ .&_ .
.. All passengers should leave the car and
move to a safe location (for instance, behind
the guardra il)¢ .&_ .
.. Engage the
parking brake to prevent your
vehicle from rolling unintentionally¢ .&_.
.. Move
selector lever to position P ¢ A .
.. If you are towing a trailer, unhitch the trailer
from your vehicle .
.,. Take the
jack and the spare tire out of the
luggage compartment¢
page 270,
¢page 271.
&_ WARNING
You or you r passengers could be injured
while changing a wheel if you do not fol­
l ow these safety precautions:
-If you have a flat tire, move a safe dis­
tance off the road. Turn off the engine,
turn the emergency flashers on and use
other warning devices to alert other mo­
torists .
- Make sure that passengers wait in a safe
p lace away from the vehicle and well
away from the road and traffic.
- To help prevent the vehicle from moving
suddenly and possib ly slipping off the
jack, always fully set the parking brake
and block the wheel d iagonally opposite
the wheel be ing changed. When one
front wheel is lifted off the ground, plac­ ing the Automatic Transmission in "P"
(Par k) will
not prevent the vehicle from
mov ing.
- Before you change a wheel, be sure the
g rou nd is level and firm. If necessary,
use a sturdy board under the jack.
-

hold on to the car to keep your ba lance
and take care not to slip.
Raising the vehicle
Th e ve hicl e must be li~ed with the jack first
before the wheel can be removed.
F ig. 224 Sill p anels : m arkin gs
Fig. 225 Sill: posi tioning th e vehicle jack
.. Activate the vehicle jack mode in the MMI:
I CAR I function button > Car sy stem s control
button
> Se rvicing & ch ecks > Air susp .:
jack mod e
> On.
.. Engage the par kin g brake to prevent your
vehicle from roll ing un intentionally.
.,. Move the
se lector lev er to p osition P .
.. Find the marking (imprin t) on the sill that is
nearest the wheel that w ill be changed
c::> fig. 224 . Behind the marking, there is a
lifting point on the si ll for the vehicle jack.
.. Turn the
veh icle jack located under the lift­
ing point on the sill to raise the jack until its
arm @i:>
fig. 225 is located under the des ­
ignated plast ic mount
c::> _&.. c::>(D .
.. Align the jack so that its arm @ c::> fig. 225
engages in the designated lifting point in
the door sill and the movable base @ lies
flat on the ground. The base @ must be
ver­
tical
under the lifting point @.
What do I d o now ? 275
.. Wind the jack up fu rther unti l the flat tire
comes off the ground
c::> _A .
Position the veh icle jack o nly under the desig­
nated lifting points on the si ll
¢fig. 224.
There is exactly one locat ion for eac h wheel.
The jack must not be positioned at any other location
c::, .&, i:>0 .
An un stable surface under the jack can cause
the ve hicle to slip off the jack . Always provide
a firm base for the jack on the ground . If nec­
essary place a sturdy board or simi lar s upport
under the jack. On
hard , sl ipper y su rf a ces
(such as tiles) use a rubber mat or similar to
prevent the jack from slipping
c::> .&, .
A WARNING
-You or your passengers co uld be in jured
while changing a wheel if you do not fo l­
low these safety pre cautions:
- Position the vehicle jack on ly at the
designated lifting points and align the
jack. Otherwise, the vehicle jack could s lip a nd cause an injury if it does not
have sufficient hold o n the vehicle.
- A soft or unstable surface under the
jack may cause the ve hicle to slip off
the jack . Always provide a firm base for
the jack on the ground. If necessa ry,
use a stu rdy board under the jack.
- On hard, slippery su rface (such as t iles)
use a rubber mat or simi la r to prevent
the jack from slipping.
- To help prevent injury to yo urself and
your passengers:
- Do not raise the vehicle until you are
sure the jack is securely engaged.
- Passengers must not remain in the ve­
hicle when it is jacked up.
- Make sure that passengers wait in a
safe place away from the veh icle and
well away from the road and traffic .
- Make sure jack position is correct, ad­
j ust as necessary and then cont inue to
raise the jack .
- Changes in temperature or load can af­
fect the height of the vehicle.

Fuse pa nel @ (brown )
No . Equipment
1 Headlight contro
l switch
2 Emergency
start coil (key
i dentification)
3 Rear door
control module
(driver's side)
5 Horn
6 Interior
lights (headliner)
Steer ing column leve r, mul-
8
tifunction steering wheel
controls, steering wheel
heating
10 E
lectric steering column
l ock
11 Driver door
control module
12 D
iagnostic connector, light/
rain sensor
14 Powe
r steering column ad-
justment
15 Power steering, A/C com-
presser
16 Brake booster
Fu se p anel © (black )
No. Equipment
1 Front seat heating
2 Windshield
wiper
3 Front exte rior lighting
4 Sun roof
5 D river power window
6 Driver
seat (pneumatic)
7 Pano ramic sunroof
8 Dynamic
steering
9 Front exterior lighting
10 W
indshield/headlight wash-
er system
11 Rear power
window (driver's
side)
12 Panoramic sunroof
Amp s
5
5
7,5 15
7,5
10/5
5
7,5
10
25
20 15
Amp s
30
30 30
20
30
7,5 20
35
30
35
30
40
Fu ses and bulb s 2 79
Front passenger side cockpit fuse
assignment
Fig . 231 Front passenger side cockpit: f use pane l with
plast ic bracket
Fu se panel @ (bl ac k)
No. Equipment Amps
1 Anti-theft alarm system 5
2 Transmission control
mod-
15
ule
3 Front climate control fan
40
4 Engine supply 35
6 Engine cont ro l modu le 5
7 Front
passenger door con-
7,5
trol module
8
Front passenger power win-
30
dow
9 E5C contro l module 10
10 ESC
contro l modu le
25
1 1 Right rear power window 30
1 2 Front
passenger seat (pneu-
7,5
matics)
•
•

280 Fuses and bulbs
Luggage compartment fuse assignment
Fig. 23 2 Luggage compartment: fuse pa nel with plas tic bracket
Fuse panel @ (black )
No. Equipment Amps
No. Equipment Amps
11 Dynam ic steer ing 5
E SC button, da ta logger, di· 12
Selector lever,
BCM-2
5
1 agnostic connector, BCM · 1,
5 13 Audi s ide ass ist 5
adap tive light ing system
14 Engine control modu le
5
2 Networking gateway
5
15 Sta rter 40
3 adap tive air s usp ension 5
4 Parking system
5 16 Left headlight/Headlight
10/5
range control system
5 Steering colum n leve r 5
6
Suspension contro l system
5
sensor
Fu se panel @ (red)
No. Equipment Amps
7 Bel
t tensione rs, airbag con-
5
trol module
Heated washe r fl uid no zzles, 1
Left reversible be
lt tens ioner
2S
2 Right revers
ible belt ten -
25
sioner
H ome link (garage door
Starter diagnos is, DC/DC
8 opener), nig ht vision system 5
3 co
nverter (S tart-Stop-Sys·
5
con trol mod ule, sport diffe r-
tern)
ent ia l, ionizer
9
Electromechan ica l park ing
5
brake contro l modu le 4
DC/DC converter (Start-
7,5
Stop-System)
5 Image proce ssing 7,5
10 Rear seat heating, coo
ler, in·
5
terior rearview mirror

Fuses and bulb s 281
No . Equ ipment Amps Fus
e pan el@ (bla ck)
•
6 R
ight headlight (headlight
10
with adaptive light)
7 ESC control module 5 No. Equipment Amps
1 Automatic luggage com
-
5
partment lid
•
8
Sound actuator, AEM control
7,5
module 3 Rear
sockets 20
5 adaptive air suspension
15
9 Adaptive cruise control 10
6 115-Vsocket 25
10 Transmiss
ion control mod-
5
ule 7 E
lectromechanical parking
30
brake
11 Climate control
system sen-
5
8 Rear seat heating 25
sors
9 Rear exterior lighting 20
Fuse pan el© (bro w n)
No. Equipment Amps
10 Rear climate control system
20
blower
1 E
lectromechanical parking
5
brake
2 Suspension control system
5 Rear
sun shade, closing aid,
11 luggage
compartment lock,
20
convenience key, fue l filler
door
sensor
3 Right rear door
control mod-
7,5
ule 12
Luggage compartment
lid
30
control module
4 Smart modul tank 5
Fuse panel ® (red)
5 Front
climate control system
15
contro ls
6 Rear climate control
system
10
controls N o. Eq uipm ent Amps
1 Rear
seat adjustment but-
5
tons
3 Left rear seat (pneumatics) 7,5
7 Networking gateway 5
5 Tra
iler hitch control module* 20
8 Cooler
15
6 Left rear seat 30
9
Interface for specia l func-
5
tions 7 Right rear seat
30
8 Trailer hitch contro l module*
20
10 Cell phone
adapter, Blue-
5
tooth handset
9 T ra iler hitch control modu le* 15
11 AEM control modu le 15 10
Right rear
seat (pneumatics) 7,5
12 Selector lever 10
Fuse pan el® (bro wn)
13 Ambient lighting
10 No. Equipment Amps
14 Rear exterior lighting 20
15 Fuel
pump
25 1 Start-Stop-System,
Radio re-
30
ceiver/sound amplifier
16 Electromechanical parking
30
brake 2 Sound amplifie
r 30
Start-Stop-System, Rear
3 Seat
Entertainment, radio 7,5
receiver/sound amplifier
5 Automatic dimming interior
5
rearview mirror
6 DVD changer 5

284 Emergency situations
@ Tips
-The discharged battery must be properly
connected to the vehicle's electrical sys­
tem. When jump starting or charging the
battery, never connect the negative
ground cable to the battery negative
post because the battery manager sys­
tem must be able to detect the battery's
state of charge . Always connect the neg­
ative ground cable to the negative
ground post of the battery manager con­
trol unit.
Use of jumper cables
Make sure to connect the jumper coble
clomps in exactly the order described below!
Fig . 233 Engine co mpartment: connecto rs fo r jump
star t cab les and c harg er
Fig. 234 Ju m p sta rt in g w it h the ba ttery of anot her ve ­
h icle :@ - booster battery, @-discharge d ve hicle bat­
tery
The procedure described below for connecting
jumper cables is intended to provide a jump
start for your vehicle.
Vehicle with discharged battery:
•Turnoff lights and accessories, move lever
of automatic transmission to N (Neutral) or
P (Park) and set parking brake.
Connect POSITIVE(+) to POSITIVE(+)
(red)
• Open the red cover on the pos itive terminal
¢ fig. 233 .
1. Connect one end of the red positive cable
on the
jump start bolt c::;, fig. 234 @ (bolt
under the red cover = "positive ") of the ve ­
hicle to be started @.
2. Connect the other end to the positive ter-
mina l@ of the booster battery@.
Connect NEGATIVE (-) to NEGATIVE (-)
(black)
3. Connect one end of the black negative ca­
ble to the negat ive terminal @ of the
booster battery @.
4. Connect the other end to the
jump start
pin © (bolts with hex head bolt= "nega­
tive") of the vehicle to be started @.
Starting the engine
• Start the engine of the veh icle w ith the
booster battery@. Run the engine at a
moderate speed.
• Start engine with discharged vehicle battery
@ in the usual manner.
• If the engine fails to start, do not keep the
starter cranking for longer than 10 seconds.
Wait for about 30 second s and then try
aga in.
• With engine running, remove jumper cables
from both vehicles in the exact
reverse o r­
de r.
• Close the red cover on the positive term inal.
T he battery is vented to the outside to prevent
gases from entering the veh icle inter ior. Make
sure that the jumper clamps are well connect­
ed with their metal parts in full contact with
the battery terminals.
_& WARNING
To avoid serious personal injury and dam­
age to the vehicle, heed all warnings and
instructions of the jumper cable manufac­
turer. If in doubt, call for road service.
- Jumper cables must be long enough so
that the veh icles do not touch.
-

-When connecting jumper cables, make
sure that they cannot get caught in any
moving parts in the eng ine compart­
ment .
- Before you check anything in the engine
compartment, always read and heed all
WARNINGS
¢ page 231.
(D Note
Improper hook-up of jumper cables can r u­
in the generator.
- Always connect POSITIVE( +) to POSI­
TIVE(+), and NEGATIVE(-) to NEGATIVE
( - ) gro und post of the battery manager
control unit .
- Check that all screw plugs on the battery
cells a re screwed in firmly . If not, tighten
pl ugs p rior to connecting clamp on nega ­
tive battery term inal.
- Please note that the procedure f or con­
nect ing a jump er cable as desc ribed
above appl ies spec ifically to the case of
you r vehi cle be ing jump started. When
you are giv ing a jump star t to an othe r ve­
hi cle, do
not connec t the negat ive (-) ca­
ble to the negat ive (-) terminal on the
discharged battery @¢
fig. 234. In ­
stead, securely connect the negative( -)
cable to e ithe r a solid metal component
that is firmly bolted to the engine block
or to the e ng ine block itse lf. If the bat­
te ry tha t is being charged does not vent
to the outside, escaping batte ry gas
could igni te and exp lode!
Emergency towing
with commercial tow truck
General hints
Your Audi requires special handling for tow ­
tng.
The follow ing information is to be used by
commercia l tow tr uck operators who know
h ow to ope rate thei r equipme nt safe ly.
Emergenc y situ ation s 285
-Ne ver tow your Audi. Towing will cause
damage to the engine and tran smission.
- Never wrap the safety chain s or w inch ca­
ble s around the brake lines.
- To prevent unnece ssary damage , your Audi
must be transported with a flat bed tru ck.
- To load the vehicle on to the fl at bed , use
the towing loop found in the vehicle tools
a nd attach to the front or rear anchora ge
¢ page 285 and ¢ page 286 .
_& WARNING
A vehicle being towed is not safe for pas ­
sengers. Never allow anyo ne to ride in a
vehicle be ing towed, for any reason.
Front towing loop
Only install the front towing loop when it is
needed.
Fig. 23 5 Front bu mpe r: cove r
Fig. 236 Fr ont bu mpe r: sc rew ing in t he tow ing loop
-
The towing loop f its into the threaded hole lo ­
cated on the right s ide of the front bumpe r
and cove red by a sma ll cove r when not in use .
.. Remove the tow ing loop from the vehicle
too l kit .