Tài Liệu Hộp Số Audi R8 Power Transmission

Limited slip diff erential, see page 28 Manual selector mechanism with 6-speed manual gearbox or automatic selector mechanism with shift by wire technology in the R tronic, see page 10..

All rights reserved.

Technical specifi cations are

Self Study Programme 613

For internal use only

!

The Audi R8 sees Audi off ering, for the fi rst time, a

high-perform-ance sports car based on a mid-engine concept

The engine positioning fore of the rear axle helps to ensure a

balanced weight distribution and a low centre of gravity

This basic confi guration allows a high level of driving stability and

good transverse acceleration

Driving dynamics are further enhanced by the combination of a

bespoke mid-engine concept and quattro all-wheel drive, with a

strong emphasis being placed on sportiness and driving

enjoy-ment

Due to the mid-engine concept and the demands on driving dynamics, the quattro full-time all-wheel drive system in the Audi R8 has been implemented in a diff erent way to previous Audi quattro drive systems

In the case of the mid-engine concept with quattro all-wheel drive

in the Audi R8, drive is transmitted dynamically to the front axle by means of a viscous coupling Furthermore, a limited slip diff eren-tial in the rear axle drive improves rear axle traction under high transverse acceleration

When buying the Audi R8, the customer can elect to change gear

manually using the 6-speed manual gearbox with double-plate dry

clutch or to drive away and change gear fully automatically using

the optional R tronic gearbox

An innovative selector mechanism allows the driver to make the

choice of driving in Automatic mode or changing gears manually

In addition, the driver can select Sport mode

Want to fi nd out more about the technology behind this power

transmission system? If so, read on and learn all you need to know

about power transmission in the Audi R8

This self study programme teaches a basic knowledge of the design and functions of new models, new

auto-motive components or new technologies

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.

Always refer to the current technical literature when carrying out maintenance and repair work

Note

Reference

613_006

613_007

Front axle drive 0AZ

Specifi cations _15Viscous coupling _16Lube oil supply _18Operating instructions _19

Manual and automatic gearboxes

Sectional view of basic gearbox _20Specifi cations _226-speed manual gearbox 086 _23Automated 6-speed manual gearbox 086 – R tronic _24Gear set – internal shift mechanism – synchromesh _26Rear axle drivewith limited slip diff erential _28Lube oil supply _30Gear oil cooling _32

Electronic control unit

Automatic gearbox control unit J217 58Basic settings – adaptations 59Encode control unit 59Functions – displays/warnings 60Functions – ignition key removal lock 61Functions – starter control unit _61Function diagram 62CAN information exchange 64Sensors 66Actuators 70

Service

Tow-starting/towing _73

Annex

Index 74Test your knowledge (Part 1) _45Test your knowledge (Part 2) _65

Contents

Mid-engine concept with quattro all-wheel drive

The outstanding performance is the quattro® all-wheel drive

system is based on a weight distribution of 44 : 56 in favour of the

rear axle If needed, up to 420 Nm of drive can be transmitted

dynamically to the front wheels by a viscous coupling

The manual gearbox 086 and the R tronic use a near-identical basic

gearbox This is a full synchromesh 6-speed manual gearbox

A high synchronisation capacity and short throws allow slick

gear-shifting

A double plate clutch transmits the engine power to the gearbox

The R tronic has an electro-hydraulic shift unit which provides for drive-away and performs gear changes fully automatically This type of gearbox is therefore referred to as an automated manual gearbox Several aspects of the basic gearbox have been modifi ed for this purpose The transmission ratios are identical to those of the manual gearbox, but in both cases they are

adapted depending on engine type

Limited slip diff erential, see page 28

Manual selector mechanism with 6-speed manual gearbox or automatic selector mechanism with shift by wire technology in the R tronic, see page 10.

Drive shaft

R tronic hydraulic unit

R tronic shift actuator, see page 36

or the shift unit in the manual gearbox,

see page 6

6-speed manual gearbox 086 or optional

automated 6-speed manual gearbox 086

(R tronic)

Introduction

613_008

The quattro concept in the Audi R8 is a slip-controlled

all-wheel drive system The rear axle is the main drive axle Engine

torque is transferred through a spur gear to the rear axle diff

eren-tial, where a limited slip diff erential ensures a continuous fl ow of

drive torque even under high transverse acceleration Engine

torque is transmitted to the viscous coupling through a second

spur gear in the front axle drive, i.e without the centre diff erential

Depending on the speed diff erential between the front and rear

axles, the viscous coupling transfers a defi ned amount of torque to

the front axle drive Here, an open diff erential distributes the

torque equally to the front and rear

The EDL control unit is specially adapted to the R8 drive concept

and assists torque distribution in the usual way

Drive concept

Front axle drive of 0AZ with viscous coupling, see page 14

Front axle diff erential

Front axle drive

Schematic diagram of power fl ow

Viscous coupling – transmits a defi ned amount of torque to the front axle

Front axle drive spur gear Rear axle diff erential with limited slip diff erential

Rear axle drive spur gear

Manual gearbox gear set

Drive shaft – transfers the drive torque to the front axle gearbox It is located inside the engine (it runs through the engine oil pan), which means

it is not visible from the exterior

The Audi R8 with manual gearbox is equipped with a gate shift

system which allows short and slick gear changes and provides exact

feedback on the gear engaged The high-quality matt fi nish

alu-minium used underscores the sporty character of the Audi R8

To start the engine on models with a manual gearbox, the clutch

must be fully depressed This information is provided by the clutch

pedal switch F36 on the clutch slave cylinder as a precaution against

unintentional drive-away at start

Shift movements are transmitted from the selector mechanism to

the gearbox via two selector cables (Bowden cables)

The robust housing and lever parts as well as the high-quality

bearings and joints in the selector mechanism and on the

gearbox shift unit provide for very direct transfer of shift commands

to the gearbox In addition to the high-quality fi nish, a very direct

and sporty shift feel is conveyed

The selector cables are set using the quick-release fasteners on the gearbox.

Selector cable for gear selection Direction of travel

Selector cable for shift gate selection

Reversing lights switch F4

Selector mechanism – manual gearbox

Selector mechanism

Ball joints in the joint forks provide for direct transfer of shift movements.

Overview of the external and internal shift mechanisms

Shift locks on the selector shaft (and selector lever)

Clutch pedal switch F36 –

mounted on the clutch slave cylinder

Circuit diagram – clutch pedal switch F36

Notes on operation

The gate shift selector off ers sporty gear-shifting and a sporty

look When changing gate, e.g to shift from 2nd to 3rd gear (or

vice versa), the shift lever and the fi nger of the aluminium gate can

come into contact with one another during the gearshift This

produces an audible clicking sound because it is not possible to use

a damper element for noise reduction It is therefore important to

ensure, fi rstly, that the selector mechanism is set correctly and,

secondly, to ensure that gearshifts are performed exactly

Launch Control Program

A Launch Control Program is available for the R8 with V10 engine

and manual gearbox The Launch Control Program provides

maximum power delivery from a standing start Refer to the user

manual for details of requirements, operating instructions and

other information

Ring magnet – is located on

the piston of the clutch

slave cylinder

Movement of the piston with ring magnet

on actuation of the clutch pedal

Maximum clutch pedal travel

Reed contact 1 (NC contact) – CCS signal

Signal for deactivation

of cruise control

Signal for start enable (interlock)

Reed contact 2 (NC contact) – start enable signal

Possible collision point when shifting from 2nd to 3rd gear

Normal position of selector lever –

in centre of shift gate 3/4

Position of ring magnet

when clutch pedal is in

Clutch pedal switch F36

To start the engine on models with a manual gearbox, the clutch

must be fully depressed This is indicated by the clutch pedal

against unintentional drive-away at start

docu-ments as clutch position sender G476 This can lead to irritation and confusion with the clutch position sender fi rst mentioned on page 40

613_012 613_013

613_014

R

Manual gearbox shift unit – engaged in R position

Reversing lights switch F4

Selector shaft

Shift detents of the selector shaft

and selector lever – shown here

engaged in R position

Shift detent of the manual gearbox

Detent for each of the gears and for the home

position of the shift fi nger (and the selector

lever) in the centre of shift gate 3/4

The ball socket in the selector shaft is on one

side only

This axial detent is eff ective only

outside the neutral position.

The illustration shows the shift detent in the neutral/home position of shift gate 3/4.

Reversing lights switch F4

The reversing lights switch F4 is supplied with term 15 via a fuse

As soon as the selector lever is moved into the reverse gate, switch

F4 connects term 15 directly to the onboard power supply control

unit J519

The onboard power supply control unit J519 actuates the reversing

lights and relays the signal for the automatic anti-glare rear-view

mirror Y7 to the gateway J533 by convenience CAN bus

The gateway, in turn, supplies the corresponding control units via

their respective bus systems

The information supplied by the reversing lights switch F4 is required for the following functions:

• Activation of the reversing lights

• Automatic anti-glare rear-view mirror/door mirror

• Activation of the front passenger door mirror fold-away tion

func-• Activation of the parking aid or reversing camera

• Audi hold assist (ESP)

613_015

Selector lever position display Y5

Refer to function chart on page 62

Selector lever sensors control unit J587

O-ring for

noise reduction

Permanent magnet

Bottom end of selector lever

Hall sensors

Sport program button E541 – is read in by selector lever

sensors control unit J587 The information "Sport mode"

is relayed from J587 to the gearbox control unit J217

and to the engine control unit by CAN data exchange

Refer to page 64 for further information.

Selector mechanism – R tronic

In the R tronic there is no mechanical connection between the

selector mechanism and the gearbox Selector lever positions and

shift commands are registered, evaluated by the gear lever sensors

control unit J587 and sent to the gearbox control unit J217 by

CAN data bus

The gearbox control unit controls the electro-hydraulic control unit

on the gearbox based on this information This control mode is

referred to as "shift by wire"

The R tronic selector mechanism diff ers not only visually from the selector mechanisms of the other automatic gearboxes

The shift diagram has been specially adapted to suit the functional principle of the automated manual gearbox

The selector lever has two lockable normal positions (left and right positions) from which the corresponding functions can be selected (see Fig. 613_018)

The selector lever sensors control unit J587

determines the selector lever positions for the gearbox control unit,

… controls the LEDs in the selector cover and in the selector lever position display Y5,

… transmits all information to the automatic gearbox control unit J217 by powertrain CAN bus,

… is the interface to the sport program button E541

The selector lever positions are monitored by multiple Hall sensors At the bottom end of the selector lever there is a permanent magnet which controls the corresponding sensors according to the selector lever position The selector lever sensors

of the J587 evaluate the signals and transmit the selector lever positions to the gearbox control unit J217 J217 utilises this information to identify the driver's input and controls the valves of the hydraulic control unit to engage the corresponding gears and clutch functions

613_016

613_017

Selector lever Faulty:

Selection of automatic mode

Selection of forward gear or upshift

Selection of reverse gear

Downshift

Selection of neutral position

Selection of neutral position

Selector lever in right-hand normal position

Selector lever in left-hand normal position

From the locked left-hand normal position, the drive can select Automatic mode (by moving selector to "A"), issue manual shift commands (by moving selector to + or –) or put the gearbox into neutral In the locked left-hand selector lever position, the gearbox may, depending on prior selection, either be in neutral or engaged

in a forward gear When the engine is running, the brake pedal must be depressed in order to select Automatic mode or to engage

Operation

Selector lever in right-hand normal position

From the locked right-hand selector lever position N, reverse gear

can be selected by pulling the selector lever back to R

To select reverse gear

… the vehicle must be stationary

In the locked right-hand selector lever position, the gearbox may,

depending on prior selection, either be in neutral or engaged in a

forward gear

Gearbox neutral position

When changing from one locked normal position to the other, the

gearbox is put into neutral (no gear is selected) To this end, the

brake pedal must be depressed when the engine is at a standstill

This prevents the vehicle from rolling away unintentionally

Selector mechanism system malfunction

In the case of the following malfunctions, the adjacent message is

indicated:

• Malfunction in the selector lever sensors control unit J587

• Interruption in the power supply to the selector mechanism

• Interruption in the data bus connection to the selector

mecha-nism

If the gearbox was in Manual mode when the malfunction

occurred, it switches over to Automatic mode Gears can still be

shifted manually using the selector paddles on the steering wheel

Reverse gear can no longer be selected First gear can be selected

from the neutral position using the + selector paddle

if the gearbox is kept in neutral for longer than 1 second

613_018

613_019

613_020

613_021

Special aspects of operating R tronic

There is no park position or parking lock Since a gear can be

engaged and the clutch closes automatically when R tronic is

deenergised, the vehicle can be secured against rolling away by

selecting either 1st gear or reverse (R) gear To securely shut off

the vehicle, the handbrake must also be applied (as is the case with

a normal manual gearbox)

If the gearbox is in neutral, a gear must be selected manually

A gear which has already been selected remains engaged after

turning off the ignition

The engine can only be started when the footbrake is depressed

R tronic always shifts into neutral when the engine is started

This prevents the vehicle from driving away unintentionally when

the accelerator is depressed

The driver can select 1st gear, reverse gear or neutral with the

ignition turned on (without the engine running) To do so, the

brake pedal must be depressed Gear-shifting noise and the

running noise of the hydraulic pump are audible

If the gearbox is in neutral after ignition is turned OFF, a gear can

still be selected manually for approx 30 sec after applying the

brake (as long as the selector lever position display is lit)

The Audi R8 with R tronic does not have an ignition key removal

lock

Gearbox in neutral

If the neither the accelerator nor the brake pedal is depressed

when the vehicle is stationary and the engine running, neutral is

engaged automatically after 10 sec

Drive-away characteristics

Gearboxes have specifi c drive-away characteristics

Automatic gearboxes usually produce a certain amount of drive

torque when the engine is idling and a gear selected This is known

as "creep torque" The vehicle begins to move away if its is not held

with the brake

R tronic dos not generate creep torque when the engine is idling

and a gear selected.

R tronic automatically opens the clutch wide and interrupts power

fl ow when the vehicle is stationary, the engine idling and a gear

selected This state is similar to that which occurs with a manual

gearbox when the clutch is depressed

No noticeable feedback is provided as to whether a gear has been

selected or not For reasons of safety, neutral is engaged after

approx 10 sec when the engine is idling and a gear selected

unless throttle or brake is applied during this time

"Holding" the vehicle on gradients by balancing the clutch and accelerator pedal will result in heavier clutch wear and cause the clutch to overheat Refer to page 44

Audi hill hold assist is optional If a gradient is detected and the footbrake is applied when the vehicle is stationary, the built-up brake pressure is held for a short time after releasing the brake This aids starting on gradients by eliminating rollback

Driving in Manual mode ( tiptronic)

Manual mode (Tip-in function) can be selected by operating the shift paddle on the steering wheel or by moving the selector lever into the plus or minus position In this case, Manual mode remains permanently activated To change over to Automatic mode, the selector lever must be moved towards "A"

By encoding the gearbox control unit accordingly, the Tip-in tion can be adapted in such a way that it automatically switches back to Automatic mode a defi ned amount of time after a Tip command is issued using the steering wheel shift paddles Refer to page 59 for further information

func-Driving in Sport mode

During normal operation in automatic mode, the shift operations are confi gured with an emphasis on comfort This results in longer shift times

A sporty setup can be provided for the driving and shift tics by selecting Sport mode (button E541)

characteris-Sport mode is eff ective during both the automatic and manual shift modes In Automatic mode, the shift points are adjusted to higher engine speeds and the shift times reduced

In both the Manual and Sport modes, the emphasis is on mance The gearshifts are very short and crisp The gearbox does not shift up automatically when when a certain engine speed is reached A kickdown function is available in manual Sport mode.The basic principle is: the higher the engine speed and load, the faster the gearshift Customers who are accustomed to the

perfor-"normal automatic gearbox" may object to the at times abrupt gear changes However, this characteristic is integral to the phi-losophy of this sports car

Sport mode also has an impact on the engine control unit The ECU changes over to a more spontaneous accelerator pedal characteristic and the exhaust fl aps are opened earlier

Operating noise of R tronic

R tronic is an automated manual gearbox As is the case with a

manual gearbox, a clicking sound can be heard from the gearbox

when engaging and changing gears

The "idler gear rattle" typical of manual gearboxes may also be

audible Idler gear rattle is caused by uneveness in the rotational

motion of an internal combustion engine These rotary oscillations

are transmitted to the gearbox gear set Due to design-related

backlash between the fi xed gear and the idler gear as well as the

inertia of the idler gears, the traction and thrust fl anks of the gear

teeth may collide with one another in a rhythmic fashion This

manifest itself as a rattling noise, which generally is noticeable

when the engine is idling and when coasting at low speed and low

engine load This characteristic is particularly marked when the

gearbox is at operating temperature

This eff ect is enhanced by sound refl ection, e.g if the vehicle is in

an enclosed space or when driving along narrow lanes between

buildings with the window open

Idler gear rattle can be reduced by vibration damping measures,

e.g in the clutch plate, but it usually cannot be eliminated entirely

The electro-hydraulic control unit of the R tronic is a largely

inde-pendent system, since hydraulic pressure is supplied by an

electri-cally driven oil pump This is why it is possible to perform

gear-shifts and actuate the clutch even when the engine is not running

Starter control unit

See page 61

Special features and instructions for operation of the clutch

Refer to "Clutch" on page 44

The R tronic hydraulic system operates at a system pressure of

40 to 50 bar The oil pump produces this pressure and admits a certain amount of oil into a pressure accumulator When the shut-off pressure of approx 50 bar is reached, the pump is deacti-vated The system is supplied with pressure from the pressure accumulator, and the pump is reactivated when the starting pressure of 40 bar is achieved

If the ignition is not turned on for a prolonged period of time, e.g because the vehicle is parked, the pressure decreases slowly as a result of internal leakage To ensure that the system is immedi-ately ready for operation, the oil pump is activated as soon as the driver's door is opened if the oil pressure is below the starting pressure The pump can be heard running

The auxiliary water pump can also be a source of audible operating noise when the engine is not running When the hot engine is shut

off , the auxiliary water pump can run on for up to 7 minutes Gearshifts are performed at a higher pressure for the fi rst 100 km This allows for higher shift forces if the selector mechanism is new and has not been run in yet

This measure is also taken if a gearbox control unit has been replaced (refer to page 58)

Displays in the driver information system ( DIS)

See page 60

Blip of throttle during downshifts

Downshifts are always executed with a blip of the throttle The

lower the engine speed, the lower the intensity at which the

throttle is blipped In Sport mode and Manual mode, the blip of

the throttle is particularly pronounced at high engine speeds

When downshifts are performed at an engine speed of

approx. 2500 rpm, the blip of the throttle is relatively light and

barely noticeable

Launch Control Program

A Launch Control Programm is available in the R8 with R tronic The Launch Control Program provides maximum power delivery when accelerating from a standing start Refer to the user manual for details of requirements, operating instructions and other information

The front axle drive is driven directly by the manual gearbox

without an intermediate centre diff erential

A viscous coupling is integrated in the front axle drive If

neces-sary, it transmits up to 160 Nm of torque to the pinion shaft Input

torque is increased by a factor of 2.6 to approx 420 Nm by the

fi nal drive ratio This torque is distributed equally in the centre

diff erential to both front drive wheels

The viscous coupling reacts to diff erences between the input and

output speeds and transmits only a small amount of drag torque if

the speed diff erential is small

This compensates for diff erences in speed between the front and

rear axles, e.g when cornering (small speed diff erential)

Conse-quently, there is no need for a centre diff erential

A

B

613_022

Viscous coupling mount from January 2010

Silicone oil fi ller hole seal Viscous coupling

Silicone oil

fi ller hole seal

Pressure relief valve From week 02/2009

The silicone oil fi ller hole seals and the pressure relief valve are composed of diff erent sectional planes.

Front axle drive 0AZ

To avoid having to replace the fl ange shafts in order to change the shaft oil seals, the shaft oil seals are press-fi tted more deeply than

in normal production

Consequently, the lip seal of the shaft oil seal runs on a new liner

As a result, the sensitive lip seal is subjected to less stress, which

in turn improves durability and leak-tightness

Key:

(one oil supply) – no change interval – lifetime fi lling

• Special silicone oil in the viscous coupling (hermetically sealed housing)

613_024

Viscous coupling mount

to January 2010

Specifi cations

The viscous coupling is a kind of fl uid clutch It consists of a

her-metically sealed clutch housing and a corresponding number of

inner and outer plates The outer plates mesh with the clutch

housing (torque input) The inner plates mesh with the output hub

(torque output)

The clutch housing is fi lled with a special-grade silicone oil

This silicone oil has a relatively low viscosity at normal

tempera-ture and becomes increasingly viscous when heated

The inner and outer plates have circular and slotted recesses

around their entire circumference The space between the plates is

fi lled with silicone oil The plates do not come into contact with

one another in the normal operating range Due to the presence of

silicone oil between the plates, only a small amount of drag torque

is transmitted at low slip This compensates for diff erences in

speed between the front and rear axles, e.g when cornering (low

speed diff erential)

When the speed diff erential between the outer plates and the

inner plates increases, the silicone oil is sheared off at the recesses

in the plates This generates heat, which makes the silicone oil

more viscous The result is transmission of power between the

torque input and the torque output of the viscous coupling to an

extent dependent on the speed diff erential and heating

Torque output Clutch housing

Torque input

Outer plate

Inner plate Outer plate

Output hub with inner plate carrier – torque output Clutch housing

Lube oil port

Schematic diagram of the viscous coupling

Silicone oil Inner plate

Seal

Viscous coupling

613_025

613_026

Outer plate, torque increase without pressure relief valve

1st activation threshold of the pressure relief valve

Hump eff ect

2nd activation threshold of the pressure relief valve (if load is still present)

Clutch torque

In sections of the outer plates, each tooth is shaped in such a way that it

serves as a spacer This ensures that the required clearance between the

inner and outer plates is maintained The clearance space is fi lled with

silicone oil The plates do not come into contact with one another Power

is transmitted through the silicone oil.

As the speed diff erential increases, the clutch torque initially rises

rapidly to a defi ned value of 160 Nm and then levels off If the

speed diff erential remains unchanged, a hump eff ect will occur

after a certain period of time

The time at which the hump occurs is essentially dependent on the

speed diff erential, duration of slip and operating temperature This

cannot be exactly predicted

The rule of thumb with a viscous coupling is that the greater the

slip, the greater the amount of torque transmitted Potentially this

could even lead to 100% transmission of power for a short period

of time This characteristic of the viscous coupling is known as the

"hump eff ect" (see diagram) The hump eff ect is caused by a sharp

increase in temperature and the accompanying rise in pressure

inside the clutch housing The hump eff ect causes mechanical

friction between the inner and outer plates, resulting in a sharp

increase in the amount of torque transmitted The speed diff erence

decreases markedly between the outer and inner plates The

silicone oil therefore incurs less friction and cools down, which in

turn reduces the amount of power transmitted This process begins

anew if the load on the clutch is maintained

The torque and power transmission confi guration (characteristic)

of a viscous coupling is mainly dependent on the following

param-eters:

• Inner and outer diameters of the plates

• Number of plates

• Viscosity of the silicone oil

• Filling level of the silicone oil

Characteristic curve of clutch slip as a function of slip and slip duration

If the viscous coupling is placed under extreme load, the pressure relief valve opens and silicone oil is discharged from the clutch housing The amount of torque which is transmitted by the viscous coupling is permanently reduced after the pressure relief valve has been activated The silicone oil cannot be checked or refi lled

If complaints are received concerning power transmission, the viscous coupling must be replaced The silicone oil does not mix with the axle oil and deposits in the oil pan The performance of the fi nal drive and diff erential is not aff ected

The viscous coupling in the Audi R8 is rated to transmit approx

160 Nm of torque at a speed diff erential of 100 rpm The viscous coupling should not incur hump even under heavy load A rapid increase in torque is not desirable for reasons of driving dynamics

To prevent hump from occurring, a pressure relief valve is built into the clutch housing (from February 2009) If too much load is placed on the viscous coupling, the temperature and pres-sure in the clutch housing will rise sharply If the pressure exceeds approx 20 bar, this causes the pressure relief valve to open, which

in turn reduces the amount of torque transmitted and prevents hump from occurring

613_001

The fi nal drive 0AZ has an oil chamber which is fi lled with axle oil

(hypoid oil) There is no change interval for the axle oil (lifetime

fi lling)

From model year 2008 onwards, the oil chamber vent is

diff erently positioned and the previous rubber valve is replaced by

a spring-loaded plate valve When the fi nal drive heats up, a slight

excess pressure builds up inside the oil chamber, causing the valve

to open When the fi nal drive cools down, a slight vacuum

devel-ops inside the oil chamber and decreases automatically over a

prolonged period (> 12 hours) due to micro leaks

The viscous coupling has its own hermetically sealed oil supply,

which is fi lled with special silicone oil (refer to page 16)

Lube oil supply

Operating instructions

• For performance testing and road simulation, the Audi R8 may

only be run on a permanently coupled 4-roller dynamometer

This means that the front and rear axle rollers must be

inter-connected so that the wheels can be driven at the same speed

• Continuous balancing of high speed diff erentials between the

front and rear axles will damage the viscous coupling and the

front axle drive

• If the prop shaft has been removed, the Audi R8 can be driven

as a rear-wheel drive model

• A brake test can be safely conducted on a low speed

dynamo-meter A speed diff erential of less than 10 kph is not

problem-atic and is acceptable for a period of less than 5 minutes

• The Audi R8 must not be towed with the front or rear axle elevated off the ground

Background:

In the case of a speed diff erential between the front and rear axles, the viscous coupling is automatically engaged to transmit power As a result, the raised axle can break away If an axle is locked up, the viscous coupling or the front axle drive will incur damage

• At large steering angles, stresses occur in the front axle due to the toe-on on turns, causing the wheels to rub and produce a droning or rubbing noise This eff ect is intensifi ed by low aspect ratios, wide tyres, low ambient temperatures (cold tyres) and certain road surface conditions

This characteristic of the Audi R8 occasionally leads to plaints wrongly attributed to the front axle drive

com-• The viscous coupling is a maintenance-free part The silicone oil cannot be checked or refi lled If the viscous coupling is faulty or ineff ective, it must be completely replaced

Sectional view of basic gearbox

6-speed manual gearbox 086

The manual gearbox and the R tronic use an almost identical basic

gearbox This is a full synchromesh 6-speed manual gearbox

A high synchronisation capacity and short throws allow slick

gear-shifting A double plate clutch transmits the engine power to

the gearbox

Automated manual gearbox 086 – R tronic

In the case of the R tronic, an electro-hydraulic shift unit actuates

the clutch and performs gear changes fully automatically This type

of gearbox is referred to as an automated manual gearbox Several

aspects of the basic gearbox have been adapted for this purpose

The gear ratios are absolutely identical to those of the manual

gearbox, but in both cases are adapted according to engine

The diff erences between the manual gearbox and R tronic are

Rear axle drive crown gear

Input shaft connecting to front axle drive

Limited slip

dif-ferential

This screw may not be used for checking the oil

level (this will result in overfi lling).

This screw is no longer available on recent gearbox

models (refer to workshop manual).

Rear axle drive spur gear The fi gure shows the 6-speed manual gearbox 086

Special features of the gearbox

• Two-piece input shaft with spline

• Input shaft for front axle drive

• Final drive with limited slip diff erential, see page 28

• Lubrication of specifi c bearing points, gearings and idler

gears by means of the oil pump, see page 30

• Thermostat-controlled gear oil cooling (except for R8 GT),

Gear oil fi lter

Rear axle drive pinion gear Output shaft

Specifi cations

R tronic

Electro-hydraulic control unit

manufacturer

Thermostat-controlled gear oil cooling by air-oil heat exchanger

No oil change interval – lifetime fi lling

Reverse gear shift fork

Gearbox input speed sender G182

(not functional in conjunction with

manual gearbox, see page 68)

1st and 2nd gear shift forks

Ball bearing shift rods

The shift forks are attached to the shift rods by means of grub screws

Shift locks in the shift unit

Shift unit with selector shaft and fi nger

Reversing lights switch F4

6-speed manual gearbox 086

613_031

Gearbox oil system vent

Rear axle drive spur gear

Vent for hydraulic clutch control

Input shaft connecting to front axle drive

Front axle drive spur gear

Gear oil fi ller screw

Rear axle drive with limited slip diff erential, see page 28

Protective tube (fi tted from model year 2009 onwards)

Automated 6-speed manual gearbox 086 –  R tronic

Audi has elected to use an R tronic automated manual gearbox in

the R8 R tronic is notable for its near-lossless power transmission,

low weight and ultra-slick gearshifts

R tronic cannot be compared to a typical automatic gearbox with

torque converter or a double clutch gearbox

The main diff erence is that traction is interrupted completely

during gearshifts This can result in slight dive motion, which will

often be considered annoying

Depending on driving profi le and shift program, the gearshifts are comfort oriented or "short and slick" With the R tronic, comfort is secondary The seemingly abrupt gear changes may not appeal to former owners of sports saloons (new converts and movers-up), although this is an integral part of the sports car driving experi-ence

For further information on the special features of R tronic, refer to page 12

Gearbox input speed sender G182,

Gearbox oil system vent

Electro-hydraulic clutch control vent

Protective tube (fi tted from model year 2009 onwards)

Gear set – internal shift mechanism – synchromesh

Common design features and diff erences between the manual gearbox and R tronic

• Input shaft – drive shaft (two piece)

• Bearing and synchromesh

• Output shaft connecting to front axle drive

• Rear axle drive with limited slip diff erential

Gear set with fi nal drive,

input and output shafts – manual gearbox

according to engine type

the selector shaft from approx. 15° (manual gearbox) to

approx. 7° when changing shift gates This shortens the shift

throws, which in turn cuts the reaction time of the gear actuator

and allows short shift times to be achieved (see page 47)

Diff erences:

• Shift jaws of the shift forks

• Shift rod mounts

• Attachment of the shift forks to the shift rods

Each shift fork has its own axial shift lock.

Ball bearing shift rods

Thick shift jaws 2)

Flat shift rods for short shift throws and fast shift times 2)

Input shaft connecting to front axle drive

The shift forks are attached to the

shift rods by means of grub screws

Reverse

3rd gear 6th gear

1st gear

4th gear

2nd gear 5th gear

Bearing for shift rods with Tefl on anti-friction bushes

Gear set – R tronic

Input shaft – drive shaft (two piece)

613_033

In the case of the R tronic, the shift positions and limit stops of each of the gears must be adapted to the gearbox control unit The

"gear actuator basic setting" function is available on the diagnostic tester for this purpose

For more information, refer to the workshop manual and page 54

Synchromesh

Gears 1, 2 and 3 have triple cone synchoniser rings Gears 4, 5 and 6 have double cone synchroniser rings To achieve high synchronisation capacity and long life, the friction faces are coated with a special sintered lining Reverse gear has a brass single cone

Synchroniser ring

Synchroniser ring Synchroniser ring

Synchroniser ring

Large lining ring

Large lining ring Large lining ring

Intermediate ring

Intermediate ring

Intermediate ring

Small lining ring

Small lining ring

Small lining ring

The shift forks are attached to the shift

rods by means of clamping screws

613_034

613_035

613_036

Rear axle drive with limited slip diff erential

In both gearbox versions, a limited slip diff erential in the fi nal

drive improves traction at the rear axle Particularly at high

trans-verse acceleration, it ensures that drive torque fl ows continuously

Background

The classic open diff erential always distributes drive torque evenly

The left and right wheels therefore transmit the same amount of

force (50 : 50) Due to the dynamic distribution of wheel load, the

wheel on the inside of the corner defi nes how much torque the

wheels are able to transmit to the road when cornering, as it is the

one which begins to spin fi rst In this case, the inner wheel cannot

transmit any torque and therefore neither can the wheel on the

outside of the corner, resulting in loss of traction The same

applies when one wheel is, for example, driving on ice, in which

case the rear axle, again, cannot transmit any torque to the road

Accordingly, the wheels on the opposite side of the vehicle cannot

transmit any torque to the road However, a diff erential always has

a certain amount of inner friction This friction produces a small

amount of "locking torque", which acts as a "assisting torque" on

the other side of the vehicle

In the case of a limited slip diff erential, a certain amount of

torque is transmitted from the faster-turning wheel to the turning wheel (on the inside of the corner) depending on the limited slip value This results in steering eff ects which counteract the steering direction during normal cornering The vehicle initially has a tendency to understeer

slower-This behaviour changes when cornering at high speed The wheel

on the inside of the corner is relieved of load and has a tendency to spin The limited-slip diff erential transfers the torque to the wheel

on the outside of the curve allowing the axle to continue ting torque to the road

transmit-Diff erential case

Right thrust ring 1)

Diff erential side gear

Thrust ring

Multi-plate clutch

Axle spider of the diff erential gears (pay attention to correct direction of fi tting)

Left thrust ring 1)

Diff erential

gear

Diff erential gear

1) Do not interchange parts.

The clutch plates are molybdenum-coated steel plates and

therefore highly durable

The multi-plate clutch setting is made at the manufacturers

and must not be adjusted

613_037

613_038

Locking eff ect and slip value

The locking eff ect of the limited slip diff erential is adapted to the

vehicle and the desired driving dynamics The lock-up eff ect is

defi ned by the lock-up value The slip value defi nes the maximum

torque diff erence at both outputs of the diff erential (left and right)

resulting from the locking eff ect

The limited slip diff erential in the Audi R8 has a nominal slip value

of 25% under throttle and 45% when coasting

One of the adjustment parameters for the slip value is the ramp

angle, since this is a key factor defi ning the pressure applied to the

multi-plate clutches Due to the fact that there are diff erent ramp

angles for driving under throttle and coasting, the locking eff ect is

adapted to both diff erent driving situations

Operating Instructions

The limited slip diff erential has an all-mechanical action, is

self-locking and becomes eff ective as soon as drive torque is input This

can place strain on the rear wheels when negotiating tight corners

at high drive torque When this occurs, the wheels have a tendency

to rub This manifests itself as noticeable vibration in the driveline

Design and function

The drive torque transmitted from the drive pinion to the crown

gear is transmitted from the diff erential case to both thrust rings

Each of the thrust rings has four wedge-shaped recesses in which

the axle spider is mounted in bearings

The axle spider forms the axle journal for the four diff erential

gears The axle journals fl atten off at the same angle as the

recesses in the thrust rings This ensures full surface contact

between the swivel pins and the thrust rings

As soon as drive torque is input, the radial forces produced by the

thrust rings and the axle journals act in opposite directions The

wedge-shaped recesses act like ramps (inclined plane), and the

axle journals spread the thrust rings apart axially like a wedge

The axial contact pressures resulting from the wedge eff ect act on both the left and right multi-plate clutches and produce a load-dependent clutch torque

This clutch torque serves as a locking torque and produces the locking eff ect The outer plates (steel plates) interlock with the diff erential case and the inner plates engage the diff erential side gears As a result, a portion of the drive torque is transferred directly from the diff erential case to the gears

Axial contact pressures acting

on the multi-plate clutches

Radial counterforce produced by the wheels

Radial drive force

pro-duced by the crown gear

Relative movement between the axle

journal and the thrust rings

Forces in the limited slip diff erential (when driving forwards)

613_039

Lube oil supply

The gear set and the fi nal drive are supplied with gear oil from a

common oil supply The same gear oil is used in both gearbox

versions (manual gearbox and R tronic)

Controlled lubrication is provided by an oil pump, which allows a

low oil level to be maintained and guarantees lubrication even at

high transverse and longitudinal acceleration The low oil level

An oil cooler integrated in the oil circuit (air-oil heat exchanger)

reduces the thermal load on the gear oil and gearbox

components A thermostat regulates oil fl ow to the oil cooler

The oil conveyed by the oil pump is initially channeled to the

thermostat Depending on the oil temperature, the oil is either

channeled through the oil cooler or directly back to the gearbox

Oil ports in the gearcase parts distribute the oil to the lubrication

points

The input and output shaft pinion bearings are lubricated through

the hollow-drilled shafts Cross holes in the shafts channel the oil

to the bearing points

Gear oil cooler (not fi tted in the Audi R8 GT; for weight reasons, the Audi R8 GT dispenses with a gear oil cooling system)

Oil port for lubricating the fi nal drive bearing

Oil port with inlet to the

hollow-drilled input shaft

Oil port for lubricating the drive pinion set

O-rings for sealing the oil ports at the gearcase partings

Oil port with inlet to the hollow-drilled output shaft

613_040

Gear oil pump

The gear oil pump is driven by the reverse idler gear of the reverse gear

Gear oil fi lter –

no change interval

Reverse gear reversing idler

A bypass thermostat with an expanding wax element

is used as an oil temperature regulator, see overleaf.

613_041

!

Gear oil cooling

Function of the bypass thermostat with expanding wax element

Thermostat closed

The expanding wax element also acts as the gate valve of the thermostat and regulates infl ow into the radiator In the closed state, a small quantity of gear oil fl ows through the bypass and back to the gearbox The gear oil fl ows along the expanding wax element and heats it up

Thermostat open

Upwards of a temperature of approx 75 °C, the plunger begins to push the expanding wax element down against the force of the spring This opens the inlet to the radiator The thermostat is fully open upwards of a temperature of approx. 90 °C

to fl ush the individual components Care must be taken to ensure that all impurities are fl ushed out of the system

If in doubt, components such as the oil cooler or thermostat must be replaced If any impurities are left in the system, this will again lead to complaints or damage to the gearbox

Impurities can clog up the thermostat bypass, impairing the performance of or disabling the thermostat

If the cooling system is opened during repair work (draining the oil cooler), the oil must be heated to above the opening temperature of the thermostat (so that it is distributed throughout the system) in order to ensure that the gear oil level is set correctly

Special aspect of the Audi R8 GT

Due to the lightweight design of the Audi R8 GT, no gear oil

cooler is fi tted

To maintain oil circulation, "short-circuit line" is fi tted in

place of the oil pressure lines running to and from the oil

cooler

Special aspect of checking the gear oil level (all)

The previous gearboxes do not have an oil inspection plug To check

the oil level, the gear oil must be drained off completely and the

gearbox refi lled with the prescribed quantity

The what appears to be a oil inspection plug on the cover of the

fi nal drive (Fig. 613_046) of this gearbox must not be used for

checking the oil level (this will result in a wrong reading)

Recent gearbox models have an oil inspection plug which can be

used to set the oil level correctly

All gearboxes have an oil fi ller screw and an oil drain screw

Observe the instructions and information given in the workshop

manual

Oil pressure line (short-circuit line)

Oil fi ller screw

Oil drain screw

Gear oil vent

Previous gearboxes have an oil inspection plug here

This must not be used for checking the oil level.

Oil inspection plug (recent gearbox models only)

613_044

613_045

613_046

613_047

Flywheel with encoder wheel for the engine speed sender

Pressure plate with clutch plates

Clutch plate 2

The clutch plates and the pressure plates form a unit and cannot

be separated

Spacers are located between the tangential springs of pressure

plates 1 and 2 They provide the necessary clearance between the

clutch plates when the clutch is open

The spring connections, tangential springs and spacers must be in

perfect condition to ensure that the clutch opens properly

In vehicles with R tronic, the basic setting procedure must be

carried out with the diagnostic tester after replacing the clutch,

among other things (see page 59)

Both in the manual gearbox and in the R tronic, engine torque is transmitted by means of a double plate clutch The advantage of the double plate clutch is its high torque transfer capability and durability in conjunction with a relatively small diameter To keep clutch installation space to a minimum, a self-adjusting clutch pressure plate is dispensed with

Pressure plate 2 (ventilated)

Starter sprocket

Clutch plate 1

Pressure plate 1 Spacer

Spring connections (tangential springs)

613_048

Double plate clutch

Clutch

Clutch control – manual gearbox

In the case of both the manual gearbox and R tronic, clutch

disen-gagement is provided by a hydraulicallly actuated release bearing

In the case of this design, the clutch slave cylinder and the release

bearing form a unit which is installed concentrically relative to the

gearbox input shaft and the clutch

This type of gearbox has no further levers or bearing points which

cause increasing frictional losses over time in use It also provides

central, and therefore more even, clutch disengagement

As with conventional clutch controls, the manual gearbox uses brake fl uid The R tronic gearbox uses hydraulic fl uid Components which are rated specially for the fl uid in use, e.g seals and O-rings, must not come into contact with the other fl uid

Since the components are identical in terms of their design, they can easily be mixed up For this reason, particular care must be taken to ensure that the correct parts are used

The manual gearbox has a standard-type clutch breather

Hydraulic clutch control vent

Brake fl uid Pipe/hose to clutch

slave cylinder

Clutch slave cylinder with release bearing

613_049

System overview

Hydraulic oil reservoir – the oil level is checked when the hydraulic system is depressurised (at 0 bar system pressure)

The vehicle must be horizontal for this purpose (refer to workshop manual).

Gear recognition sensor 2 G616 1)

Shift fi nger

Gear lock

Selector shaft with working

piston

In the case o the R tronic, gears are shifted and the clutch is

operated electro-hydraulically by a hydraulic control unit

This comprises the R tronic hydraulic unit and the R tronic gear

actuator.

The hydraulic unit supplies the gear actuator with the required oil

pressure This purpose is served by a separate oil circuit (hydraulic

fl uid) with a system pressure of between 40 and 50 bar

The gear actuator is activated by the gearbox control unit

It changes gears and controls the hydraulic pressure applied to the

clutch according to the instructions of the gearbox control unit

The key components of the gear actuator are:

• Three electromagnetic valves for gear-shifting (N284, N285,

N286)

• One electromagnetic valve for clutch actuation (N255)

• One pressure sensor (G270)

• Two travel sensors (G604, G616)

• Selector shaft with shift fi nger, gear lock, working piston and

Supply pressure line

R tronic gear actuator

Hydraulic pump motor V387

Sensor lever Gear recognition sensor G604 1)

Sealing cover (with or without vent hose, depending on version)

Hydraulic pump inlet

Pressure accumulator

Pressure line to clutch slave cylinder

S-CAM

Non-return valve

sensors, the gear actuator and the gearbox

R tronic – hydraulic control unit

Other components integral to the automation of manual gearbox

086, and therefore R tronic, are:

• Automatic gearbox control unit J217 – see page 58

• Clutch slave cylinder – see page 40

• Clutch position sender G476 – see page 67

• Gearbox input speed sender G182 – see page 68

• R tronic selector mechanism – see page 10

• Various signals and information received from other control units by powertrain CAN bus or separate signal lines – see page 64

R tronic gear actuator 1)

R tronic hydraulic unit

Pressure accumulator

Connection for hydraulic pump motor V387

Hydraulic pump

Gear recognition sensor G604

Pressure line to clutch slave cylinder

Clutch actuator valve N255 Gear selection valve 1 N284 Gear selection valve 2 N285 Gear selection valve 3 N286 Gear recognition sensor 2 G616 1)

613_050

Notes

When performing work on the hydraulic control unit, care must be taken to ensure that the hydraulic system withstands high pressures (over 50 bar) even when the engine is at a standstill and the ignition OFF There is a danger of injury Before per-forming work on the hydraulic system, it must be ensured that the system is depressurised and that the hydraulic pump cannot be started Refer to the workshop manual and the diagnostic tester

Hydraulic diagram

design (they are not coded) To ensure that the connectors can be

connected correctly, the wiring harness connecting to the

elec-tromagnetic valves is colour-coded The valves are not usually

colour-coded, which is why the electrical connectors are easily

confused To ensure that the connectors are reconnected to the

matching valves, they must be marked unmistakably before

disconnecting

For information on the electromagnetic valves, refer to page 70

A pressure limiting valve is integrated in N284 It opens at approx 80 – 90 bar and protects the hydraulic system against excess pressure This pressure limiting function is not shown to ensure the simplicity of the hydraulic diagram

Key:

G270 Gearbox hydraulic pressure sender

V387 Hydraulic pump motor

The hydraulic diagram is shown in a pressure and stress free state

Clutch slave cylinder

Shift fi nger in neutral position

R tronic gear actuator

R tronic hydraulic unit

Throttle = R, 2, 4, 6 Overrrun = 1, 3, 5

Pressure piston of S-CAM brake 2)

Clutch control mechanism vent

Working piston of the selector shaft