brake AUDI S8 2008 Workshop Manual

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- Lack of proper maintenance as wel l as improper use of the
vehic le will impair the func tion of the emission con tro l system
and cou ld lead to damage .
<£> For the sake of the envir onment
Even when the Emission Control System is operating properly, the
exhaust gas can have a su lfur -like exhaust gas smell under some
operating states . This depends on the sulfur content of the fuel
being used. Using a different b rand of fue l may help, or fil ling the
tank with lead-free super grade gasol ine. •
Avoid damaging the vehicle
When you are driving on poor roads, or over curbs, steep ramps,
etc., make certain that low- lying parts such as spoi lers and exhaust
system parts do not bottom out and get damaged.
T his is especial ly true for vehicles with low -s lung chassis (sports
chassis)* and ful ly loaded vehicles .•
Operate your vehicle economically
and minimize pollution
General
Y o ur personal style of driving will determine the economy
of your vehicle , as well as exhaust and noise levels.
Fuel economy, environmenta l impact, and wear on your engine,
brakes and t ires largely depend on three factors :
• your personal driving style
• operat ing cond it ions
• t echnica l limitations
Controls and equip­
ment Safety first Vehicle operation
I
f you anticipate what you need to do next and drive economica lly,
you can eas ily cut your fuel consumptio n by 10 -15 percent . This
section wil l give you some tips on how you can help the environ­
ment and your poc ketboo k.
[ i ] Tips
The consumption estimates as published by ENV IRO NME NTA L
PRO TECTION AGENCY (EPA) and Transport Canada may not corre ­
spond to your actua l consumption on the road, which wi ll vary
depe nding upon veh ic le load and speed, road and weather condi­
tions, trip length, etc. •
Drive smoothly and keep a lookout ahead
Vehicles use the most fuel when they ore accelerating .
-Avo id unnecessary accelerat ing a nd braking .
Vehicles use the most fue l when they are accelerating . If you antici ­
pate what is going to happen
ne xt, you wi ll need to brake less and,
thus, acce lerate less. Let the vehicle coast whenever possib le -for
examp le when you see that the next traffic light is red. •
Avoid full throttle
Driving at moderate speeds saves fuel and improves your
mileage.
- Try and keep we ll below your car 's max imum speed.
Acce lerating gently reduces fue l consumption, engine wear, and
does no t disturb the envir onment.
Fue l consumption, exhaust emissions and engine noise increase
dispropo rtionately at h ig h speeds . If yo u drive at approxi mate ly
three quarters of top speed, fuel consumpt ion wil l be reduced by
~
Vehicle care Do-it-yourself service Technical data

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Trailer towing
Driving with a trailer
General information
Your Audi was designed primarily for passenger transpor­
tation.
If you plan to tow a trailer, please remember that the add it ional load
wi ll affect durability, economy and performance.
Tra iler towing not on ly p laces more stress on the vehicle, it a lso ca lls
for more concentration from the driver.
For this reason, always fol low the ope rating and driv ing instruc tions
provided and use common sense.
(D Note
If you are go ing to tow a trai ler, you must activate the trailer opera ­
tion
mode => page 189, "Towing a Trailer". •
Technical requirements
Traile r hit ch
Use a we ight-carrying hitch conforming to the gross trai ler weight.
The hitch must be suitable for your vehic le and trailer and must be
mounted secure ly on the ve hicle's chass is at a
technically sound
location. Use only a trailer hitch with a removable ball mount.
Always check wit h the trai ler hitch manufacturer to make s ure that
you are using the correct hitch .
Do not use a bumper hit ch.
The hitc h must be installed in such a way t hat it does not interfere
with the impact-absorbing bumper system. No modifications
should be made to the veh ic le exhaust a nd brake systems. F rom time to time, check that all hitch mounting bolts remain secure
ly
fastened .
When yo u are no t towing a trailer, re move the tra ile r hitch ball
mount. This prevents the hitch from causing damage shou ld your
vehic le be struck from
behind =>& .
Traile r br ake s
If your tra iler is equipped with a braking syste m, check to be sure
that it conforms to al l regu lations .
The tra iler hydraul ic brake sys tem must not be di rect ly co nnected to
t he vehic le's hydrau lic brake system .
Safety chains
Always use safety chains between your vehicle and the trailer.
Trailer light s
Trai ler lights must meet a ll regulations. Be sure to check with your
Aud i dea ler for correc t wir ing, sw itch es and relays .
Mirrors
If you are unable to see the traf fic behind you using the regu lar
outside mirrors, then you
must instal l extended mirrors. It is impor ­
t ant that you
always have c lear v ision to the rear.
& WARNING
After removing the tr ailer hitch , do not store it in your vehi cle . In
ca se of sudden braking , the hitch could fl y forward and injure you
or your p assenger s.•

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Operating instructions
M ax im um tra iler weig ht
A trailer for your vehicle is limited to a typ ical c lass 1 or class 2
trailer.
T ra ile r l oad d is tributi on
Be sure the load in the trailer is he ld securely in place to prevent it
from shifting forward, backward or s ideways .
Never a llow a pass enger to r ide in a trailer:::::, & in "Driving instruc­
t ions" .
Engin e coo lin g sys te m
Tow ing a trai ler makes the engine work harder. It is important that
the cooling system's performance is up to the additiona l load. Make
sure that the coo ling system has enough fluid .
Tire press ure
When towing a trailer, inflate the tires of your veh icle to t he co ld tire
pressure listed under "Full load" on the labe l located either on the
driver's side B -pil lar (visible when the door is open) or inside the fuel
filler flap . Inflate trailer tires to trai ler and tire manufacturers' spec­
ifications.
L ig ht s
The head light settings should be checked wit h the trai ler attached
before driving off. Check to make sure both vehicle and trai ler lights
are working properly .
Safe ty c ha in s
Be s ure trailer safe ty chains are properly connected from the trailer
to the hitch on the vehicle. Leave enough slack in the chains to
permit turning corners . When yo u insta ll safety chains, make sure
they will not drag on the road when you are driving.
T he chains should cross under the trailer tongue to prevent it from
dropping in case of separat ion from the hitch.
Controls and equip­
ment Safety first
Vehicle operation
0 Note
If you are go ing to tow a trai ler, you must activate the tra iler opera­
tion
mode :::::, page 189, "Towing a Trailer". •
Driving instructions
Driving with a trailer always requires extra care and
consideration.
To obtain the best possib le handling of ve hicle and trailer,
p lease note t he following :
- Do not tow a loaded trailer when your car itself is not
loaded.
- Be especia lly careful whe n passing other vehic les .
- Observe speed limits .
- Do not drive at the maximum permiss ible speed .
- Always apply brakes early.
- Monitor t he temperature ga uge .
W eight d istr ibu tion
Towing a loaded trailer with an empty car results in a highly
unstable d istribution of weight. If this cannot be avoided, drive at
very low speeds only to avoid the risk of losing steering control.
A "balanced" rig is easier to operate and control. This means that
t he tow vehicle should be loaded to the extent possible and permis ­
sib le, while keeping the trailer as light as possib le under the circum ­
stances . Whenever possible, transfer some cargo to the luggage
compartment of the tow vehicle whi le observing tongue load
requirements and vehicle loading considera tions .
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Vehicle care Do-it-yourself service Technical data

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Speed
The higher the speed, the more difficu lt it becomes for the driver to
control the rig. Do not drive at the maximum permissible speed. Reduce your speed even more if load, weather or wind conditions
are unfavorable
-particularly when going downhi ll.
Reduce vehicle speed
i mm edia te ly if the trailer shows the slightest
sign of swaying.
Do not try t o stop the sway ing by accelerating.
Observe speed lim its. In some areas, speeds for vehicles towing
trai lers are lower than for regular ve hicles .
Always apply brakes ear ly. When driving down hill, shift into a lower
gear to use the engine braking effect to slow the vehicle. Use of the
brakes a lone can cause them to overheat and fail.
Cool ant temp era tu re
The coolant temperature gauge=> page 12 must be observed care­
ful ly. If the needle moves close to the upper end of the scale, reduce
speed immed iately and/or turn off the air conditioner.
If the coolant temperature warning light in the instrument cluster
starts flas hing
-F- , pul l off the road, stop and let t he engine idle for
about two m inutes to prevent heat build-up.
& WARNING
An yone n ot properl y re str aine d in a mo ving vehi cle is at a mu ch
g re ate r ri sk in an accid ent . N ever let any on e rid e in y our car who
i s not properl y wea rin g th e res tra int s pr ov ided by Audi.
•
Trailer towing tips
Important to know
Your vehicle handles differently when towing a trailer because of
the additional weight and different weight distribution. Safety, performance and economy wi
ll greatly depend on how carefully you
l oad your trailer and opera te your r ig.
Before you actual ly tow your trailer, practice turn ing, stopping and
backing up in an area away from traffic . Keep practicing unti l you
have become comp letely fam iliar with the way your vehicle-trai ler
combination behaves and responds.
Backing up is di fficult and requires practice. Backing up with a
trai ler generally requires steering action opposite to that when
backing up your veh ic le without a tra iler.
Ma inta in a greater distance between your veh ic le and the one in
front of you . You will need more room to stop. To compensate for
the trai ler, you w ill need a larger than norma l turning radius.
When passing, remember that you cannot accelerate as fast as you n or mally wou ld because of t he added load . Make su re you have
enough room to pass . After passing, al low plenty of room for your
t rai ler befo re changing lanes again .
Avo id jerky starts, sharp turns or rapid lane changes.
[ i ] T ips
• Do not tow a tra iler during the break-in period o f your veh ic le.
• I f you tow a trailer, your Audi may require more frequent main te­
nance due to t he extra
load=> page 380. •
Parking on a slope
Do n ot park on a slope with a trailer. If it cannot be
avoided, do
so o nly after doing the followi ng:
When p arking :
-Apply the foot b rake.
- Have someone p lace chocks under both the vehicle and
the trailer wheels. _,,,

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-Wit h chocks i n place, slowly release the brakes until the
wheel chocks absorb the load .
-Turn the wheels towards the curb.
-Apply the parking brake.
-Move the selector lever to P.
When rest arting after p arking :
-Apply the foot brake.
-Start the engine.
-Move the se lector lever to D.
-Re lease the parking brake and slowly pull out and away
f rom the whee l chocks .
-Stop and have someone retr ieve the wheel chocks .
[ i] Tip s
If you move the se lector lever of the automatic transmission to P
b efor e applying th e parking brak e and b efor e blocki ng th e wheels ,
you may have to use more force later to move the lever out of the
P
position .•
Controls and equip­ ment Safety first Vehicle operation
Vehicle care Do-it-yourself service Technical data

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Cleaning and protection
General information
Regular care preserves vehicle value.
Any automobile is exposed to industrial fumes, corrosive road salt,
muddy dog feet, etc . A well cared for Audi can look like new many
years a fter purchase. Regu lar a nd correc t ca re will contribu te to
maintaining the beauty and va lue of your Audi.
Furthermore, good care may be a condition for substantiating a
warr anty claim should corrosion d amage or paint defect s occur .
Your authorized Audi dealer has a variety of dedicated vehicle- care
product s
and can adv ise whic h ones to use fo r clea ning the exterior
and interior of your vehicle.
Whether you use prod ucts recom mended by Audi or o ther commer ­
cia lly availab le cleaning agents, please make sure you app ly them
correctly.
& WARNING
• Cleaning agents may be poi sonous . Keep them out of the reach
o f children .
• Heed all cau tion label s.
• Always read directions on the container before u sing any
p rodu ct. Follo w the di re ction s carefully .
• Most chemical cleaners are concentrated and have to be
diluted.
• Use spot removing fluids only in well ventilated area s.
• Do not use gasoline , kerosene , die sel fuel , n ail polish remo ver
or other vol atile fluids . They may be toxic , flammable or ha zardous
in other way s. Do n ot wash , w ax or dry the vehicle with the igni ­
tion on or the engine running.
& WARNING (continued )
• Do not clean the under sides of chassis , fenders , wheel cover s,
etc . without protecting your hands and arms. You may cut yourself
on sha rp -edged metal parts .
• Moisture and ice on brakes may impair braking effi ciency
=> page 270 , "Gener al info rm ation ". Test the brake s carefully each
time you wash the vehicle .
~ For the sake of the environment
Select only enviro nmen ta lly friend ly c leaning pr oducts . Leftover
clean ing products should not disposed of in the household waste. •
Care of exterior
Washing
Frequent washing protects the vehicle.
Th e best p rotection aga inst environmental influe nces is frequent
washing and waxing . How often this is required depends on:
• Ho w much the vehic le is used
• Where the vehic le is parked (garage, in the open under trees,
etc.)
• T he seasonal and weather conditions
• E nvironmenta l influences
T he longer bird droppings, insects, tree resin, road and industrial
gri me, ta r, soot, road salt and ot her mater ials rema in on the ve hicle
body, the more lasting their destruc tive effects will be . High temper­
atu res caused by exp osu re to in tense s un ligh t inte nsify the c orro -
s ive effect, particularly when hum idity is high as well .
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brake dust is also corrosive. If left on for too long, brake dust can
cause pitting.
Use on ly specia l
acid-free cleaners formu lated for a lloy r ims . Safe
products are availab le at your Audi dealer. Never leave the cleaner
on the ri ms longer than specified on the label. If not rinsed off
promptly, the acid contained in some c leaners can attack the
threads o n the wheel bo lts .
Never use abrasive or metal po lishing c leaning agents . If the protec ­
t ive coating has been chipped, e.g . by kicked up road dirt, touch i t
up as soon as possible .
& WARNING
• Moisture and i ce on b rake s ma y affe ct b raking effi ciency
=> page 270 , "General information ". Te st the brakes carefully ea ch
t ime you wa sh the vehi cle .
• Alway s read and heed all WARNINGS and other information
=> page 288. •
Body cavity sealing
The body cavity sealing does not nee d to be checked.
A ll body cavit ies which could be affected by corrosion have been
t horough ly pr otected a t the factory .
This sealing does not require any inspection or additional treat ­
ment . If any wax should seep out of the cavity when the ambient
temperature is high, it can be removed with a plastic scraper and a suitable solvent .
& WARNING
Solvents can be d angerous.
• Ben zine is flammable and to xic . If you use benzine for removing
the wax , keep sparks, flame and lighted cigarettes away . Never
& W AR NING (continued )
dump benzine on the ground , into ope n streams or do wn sew age
drain s.
• Be sure to observe all safet y and env ironmental regulat ions .
Follow all in struction s on the cont ainer .
• Alway s read and heed all WARNINGS and other information
=> page 288 . •
Chassis
Hav e the underc oating c hecked for damage from tim e to
time.
T he lower body shell of your Audi is also thoroughly protected
against corrosion .
Any damage to the undercoat ing caused by road hazards s hou ld be
repaired promptly.
& WARNING
Too much undercoating in the wrong place s can cau se a fire .
• Do not appl y additional undercoating or rustproofing on or
near the exhaust manifold , exhau st pipes , catalytic converter or
h eat shield s. Wh ile dr iving , the sub stan ce used for underco ating
could overheat and cau se a fire .
• Alway s re ad and heed all WARNINGS and other info rm ation
=> page 288 . •

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•
Closing the engine hood
- Pull the hood down until the pressure from the struts is
reduced .
- Let the hood
drop down and latch in place. Do not try to
push it shut;
it may fail to engage =>& .
& WARNING
A hood that is not completely latched could fly up and block your
view while driving.
• When you close the engine hood, check it to make sure the
safety catch has properly engaged. The hood should be flush with
the surrounding vehicle body parts.
• If you notice while driving that the hood is not secured prop­
erly, stop at once and close it. •
Working in the engine compartment
Be especially careful whenever you work in the engine
compartment.
Whenever you must perform any work in the engine compartment,
for example checking and filling different fluids, there is a risk of injury, burns and accidents. To prevent personal injury always
observe the following WARNINGS. The engine compartment of any
vehicle is a hazardous area
~ & .
& WARNING
To help avoid injury, before you check anything under the hood :
• Turn off the engine. • Remove the ignition key.
• Apply the parking brake.
• I I • • I
& WARNING (continued)
• Move selector lever to "P" (Park).
• Always let the engine cool down. Hot components will burn
skin on contact.
• To reduce the risk of being burned, never open the hood if you
see or hear steam or coolant escaping from the engine compart­
ment. Wait until no steam or coolant can be seen or heard before
carefully opening the hood.
• Keep children away from the engine compartment .
• Never spill fluids on hot engine components. They can cause a
fire.
• Never touch the radiator fan. The auxiliary electric fan is
temperature controlled and can switch on suddenly.
• Never open the coolant reservoir cap when the engine is still
warm. The coolant system is pressurized and hot coolant could spray out.
• Protect your face, hands and arm from steam or hot engine
coolant by placing a thick rag over the cap when you open the
coolant reservoir.
• If work on the fuel system or the electrical system is necessary:
- Always disconnect the battery.
- Never smoke or work near heaters or open flames . Fluids in
the engine compartment could start a fire.
- Keep an approved fire extinguisher immediately available.
• To avoid electrical shock and personal injury while the engine
is running or being started, never touch:
-Ignition cables
- Other components of the high voltage electronic ignition system.
• If you must perform a check or repair with the engine running: -First, fully apply the parking brake, move selector lever to
"P"
(Park). .,_
Vehicle care

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& WAR N ING (continued )
-Always use extreme caution to prevent clothing , jewelry, or
long ha ir from getting caught in the radiator fan , V -belts o r
other moving parts , or from contacting hot parts . Tie back hair
before starting , and do not wear clothing that will hang or
droop into the engine .
• Minimize exposure to emis sion and chemi cal hazards
=> & .
& WARNING
Californ ia Proposition 65 W arning :
• Engine exhaust , some of its constituents , and certain vehicle
c omponents conta in or emit chemicals known to the State of Cali­
fornia to cause cancer and birth defects and reproductive harm. In addition , ce rtain fluids contained in vehi cles and certa in products
of component wear contain or emit chemicals known to the State
of California to cause cancer and birth defects or other reprodu c­
tive harm.
• Battery posts , terminals and related accessories contain lead
and lead compounds , chemicals known to the State of California
to cause cancer and reproductive harms. Wash hands after
handling.
0 Note
When adding f luids, always make sure that they are poured into the
proper container or filler opening, othe rwise serious damage to
vehicle systems wi ll occur.
For the sake of the environment
To detect leaks in time, inspect the vehicle floor pan from under ­
n eath regu larly. If you see spots from oil o r o ther ve hicle flu ids, have
your vehicle ins pected
by an autho rized Audi dea ler. •
Engine compartment
Ap plies to vehi cles : wi th 8 -cy lind er e ngi ne
Engine compartment overview : 8-cylinder
engine
T hese are the m ost i mpor tant i tems th at yo u c an ch eck .
Fig. 261 Typical l ayout for containe rs, engine o il d ip stic k a nd engine oil fille r
c a p
G) Winds hield/headlight washer containe r(~ ) ...... . .
© Brake fluid reservo ir ( ) ) . . .. .. .. ...... .... ... .. .
© En gine oi l filler cap ("t::r.) .. .. .... ...... ....... . _.
© Eng ine oil d ipstick (orange) .... ..... ....... ... .. .
© Power steering reservoir ...... ....... .... .. ... .. .
© Coolant expansion tank (_ L J ... ...... .... ... .... . .
323
317
312
3 11
2 7 3
315
..