Audi A3

since 1997 of release

Repair and car operation

Audi A3
+ Maintenance instruction
+ Current leaving and service
+ Engine
+ Systems of cooling, heating
+ the Power supply system and production of the fulfilled gases
+ engine Electric equipment
+ Manual box of gear shifting
+ Automatic transmission and models with a full drive
+ Coupling and power shafts
- Brake system
   Replacement of forward brake shoes
   Removal and installation of disk brake mechanisms of back wheels
   Check of thickness of a brake disk
   Removal and installation of a brake disk/support
   Adjustment of the parking brake
   Brake liquid
   Air removal from brake system
   Removal and installation of a brake hose
   Check of the amplifier of a brake
   Removal, installation and adjustment of the switch of a stoplight
   Removal and installation of the lever and cable of the parking brake
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment
+ Elektroskhema


Brake system




Separate characteristics are provided also in the text of Head and in case of obligation of their performance are allocated with a bold print

General parameters
Design Disk brake mechanisms on lobbies and back wheels. Disks of forward brake mechanisms – blown. Electronic hydraulic anti-blocking system. Hydraulic system – double-circuit, diagonal. Brake slips – bezasbestovy
Disk brake The forward The forward The back
Manufacturer FS-III FN-3
Thickness of a brake shoe, mm
the new 14 14 11.5
wear limit (with a back plate) 7 7 7
wear limit (without a back plate) 2 2
Thickness of a brake disk, mm
diameter 256/280 288 232
thickness of the new 22 25 9
wear limit 19 22 7
Brake liquid 1.5 l of DOT 4 of the FMVSS 116 specification
Diagnostic codes of malfunctions of electronic control are given by systems of braking and stabilization of stability in Specifications to Chapter 5.
Efforts of a tightening of carving connections
The moments of an inhaling of fixture are given also in the text of Head and on some иллюстрациях*.

*vydelenny in the text a bold print the moments of an inhaling are subject to exact observance; the efforts not allocated with a bold print are given only roughly
Directing bolts of a brake support of forward wheels 28 N • m
The holder of a brake support to a nave
Forward wheels 28 N • m
Back wheels 65 N • m
Brake support of back wheels to the holder 30 N • m
Mudguard, ahead 10 N • m
The lever of the parking brake on a body floor 25 N • m
Brake hose on a support 35 N • m
Bolts of wheels 120 N • m

Elements of electronic hydraulic system of stabilization of dynamic stability of ABS/EBV/EDS

1–ASR switch
2–switch of a stop signal
3–sensor of number of turns the back left
4–sensor of number of turns the back right
5–sensor of number of turns the forward right
6–sensor of number of turns the forward left
7–ABS/EBV/EDS/ASR control unit
It is built in the hydraulic control unit
8–control lamp of ABS/EDS
9–control lamp of ASR
10-control lamp of level of brake liquid
11-main brake cylinder, amplifier of a brake, brake pedal
12-hydraulic block

Elements of a control system of ABS/EDS

1–main brake cylinder and amplifier of a brake
2–hydraulic control unit
3–diagnostic socket. In the central console under an ashtray.
5–control lamp of a reserve of brake liquid
6–control lamp of ABS/EDS
7–number sensor sensor turns/wheel. Back axis
8–switch of a stop signal. Over a brake pedal
9–number sensor sensor turns/wheel. Forward axis

The brake system consists of the amplifier of a brake, the main brake cylinder with the connected hydraulic ABS block and disk brakes of lobbies and back wheels. The brake system has two contours, operating on a diagonal. One contour influences on forward right/back left, another on forward left/back right brakes. At refusal of one of contours braking of the car is carried out to one lobbies and one back by brakes. Pressure of liquid in both contours is created in the dual main cylinder by impact on a brake pedal.

The tank of brake liquid is located in an impellent compartment over the main brake cylinder, it provides with liquid all brake system.

On forward wheels the disk brakes having for the best heat-conducting path aeration are established. Back wheels are braked by continuous disk brakes.

The amplifier of a brake of the engine accumulates a part of the vacuum created in the soaked-up pipeline of the engine. At impact on a brake pedal the effort to pedals through the amplifier of a brake increases thanks to vacuum action.

Disk brakes are supplied with so-called rigid supports. At these supports only one piston is necessary for pressing brake shoes.

The parking brake affects through cables brakes of back wheels.

Work with brake system demands special purity and exact observance of instructions. In the absence of necessary experience it is expedient to address on HUNDRED.

Brake shoes are intended for use in concrete model of the car. It is recommended to apply the brake shoes resolved by the manufacturer or Federal department on control of vehicles. Such brake shoes have the corresponding marking of KBA.

At movement on wet roads it is necessary to press periodically a brake pedal for drying of disk brakes. In the course of wheel rotation moisture under the influence of centrifugal force is dumped from brake disks, but there is a film of silicone, a product of an istiraniye of rubber, greasing and the other pollution reducing efficiency of operation of brakes.
Prigara dirt on surfaces of brake shoes and rain flutes leads to formation of furrows on a surface of brake disks, a consequence of that is decrease in efficiency of braking.
When cleaning brake system the dust is allocated, which can harm health of the person therefore to inhale a brake dust it is impossible.



The anti-blocking system, interferes with blocking of wheels at sharp braking. It promotes controllability preservation in the course of braking and increases reliability of movement.


The system of electronic distribution of brake effort, by means of ABS of hydraulics distributes brake effort on back wheels. As EBV adjustment works essentially more sensitively, than the mechanical regulator of brake effort, is used considerably a bigger range of regulation.
At movement on a straight line the effort of braking is transferred to back wheels completely. That when braking on turns also to provide stability, it is necessary to reduce effort of braking on back wheels. Via sensors of number of turns the ABS system defines, whether the car directly moves or it turns. At movement on turns the effort of braking of back wheels decreases. Thanks to it back wheels can receive the maximum lateral directing effort.
EDS: The electronic blocking differential, brakes being turned wheels at a car troganiye from a place. Thanks to it the torque is transferred to driving wheels.
Electronic blocking of differential operates at a troganiye from a place and is disconnected automatically at achievement of speed of 80 km/h. Special advantages of this system: it does not render negative influence on dynamic qualities of the car and on comfort of management.
Recommendations about ABS/EBV/EDS systems
The special switch in the electronic control unit watches that system in the presence of damage (for example, cable break) or a voltage reduction of an onboard network is lower 10 In was disconnected. The situation is displayed on the dashboard by fire of control lamps. The usual system of braking thus keeps the working capacity. In the course of braking the car behaves as if the ABS system is absent.

If during movement control lamps of ABS and braking system light up, at strong braking back wheels can be blocked, as distribution of brake effort does not operate.
If during movement on the dashboard one or several control lamps light up, it is necessary to mean the following:

1. Stop for a while the car, switch off the engine and again start it.
2. Check tension of the storage battery. If tension less than 10.5 In, charge the battery.

If control lamps light up in a start of motion and then after a while die away, it specifies that tension of the storage battery at first was too low, and then during movement as a result of a charging the generator again raised.

3. Check, whether plugs of the storage battery are reliably fixed and whether they have reliable contact.
4. Put the car on supports, remove wheels and check the electric wires going to sensors of number of turns of wheels on existence of external damages (retyranny). More detailed check of ABS/EBV/EDS should be carried out in conditions HUNDRED.

Before performance of electrowelding works it is necessary расстыковать the control unit socket. Connection undocks only at the switched-off ignition. At performance of paint and varnish works it is authorized to heat up quickly the control unit to temperature no more + 95°С, and it is long (Max. 2 hours) to temperature +85°С.