General, Technical Data (Brake System (coupe)) Audi A5 I

BRAKE FLUID

Note. Brake fluid is hygroscopic, i.e. it has the ability to absorb water and moisture from the air.

If water has been absorbed, the boiling point will drop, i.e., during high braking temperatures the brake fluid may develop steam bubbles and cause the brakes to fail.

Scheme 1

Over time, brake fluid will darken in color. Dark-colored brake fluid does not specify anything about its quality. The color forms due to chemical reactions.

Even the smallest amount on a seal or boot can cause the part to change and thereby affect the function of the brake system. The results of an unclean brake system first show themselves months later, causing increased repair costs, especially on vehicles with ABS.

A = Boot - Original size

Scheme 2

B = Boot - Swollen through contact with mineral oil

It is Implied by the Previously Mentioned Points That

Keep containers of brake fluid closed securely. This is to make sure that no oil, dirt or cleaning materials and no humidity can enter the container.

Store containers of brake fluid away from oil (even hydraulic oil) and cleaning fluids to prevent an accidental mixing of both fluids or even filling the brake system with the wrong fluid.

The use of brake fluid approved by Audi is recommended.

BRAKES INSPECTION

The testing takes place on a test stand.

When testing, place selector lever in driving position N for vehicles with automatic transmission and in neutral position for vehicles equipped with manual transmission.

Always observe the test stand manufacturer instructions.

Note. Electronic brake control systems are inoperative when the ignition is switched off.

If Testing Equipment is Needed on Road Tests, Follow the Information Below

Scheme 3

CERAMIC BRAKE ROTORS, EVALUATING

Note. Ceramic brakes are installed only in the front.

Scheme 4

1. Cooling Channels
2. Friction Surface
3. Base Material

Ceramic Brake Rotor Visual Characteristics

Checking Threaded Connectors on the Brake Rotor Ring and Brake Rotor Cup

The friction surface on a new brake rotor already has stress cracks made during the production process. These stress cracks are all different.

Scheme 5

Note. Stress cracks do not mean the ceramic brake rotor is faulty.

The stress cracks are somewhat visible and can be different from each other in strength.

Surface Cracks in Cooling Duct Crosspieces

The cracks on the surface of the cooling channels -arrow- were produced during the manufacturing process.

Scheme 6

Note. Surface cracks in the cooling duct cross pieces do not mean the ceramic brake rotor is faulty.

Cracks in Ceramic Brake Rotor Connection Area

Scheme 7

Checking Threaded Connectors on the Brake Rotor Ring and Brake Rotor Cup

If the ceramic brake rotors have cracks near the threaded connectors on the cup leading to the friction surface on the brake rotor -arrows-, then the brake rotors must be replaced.

Scheme 8

Crack in the threaded connection area not permitted.

Scheme 9

Replace the Brake Rotors on Both Sides of the Axle When

1. The brake rotors must replaced because they are worn.
2. The replacement brake rotor has been technically modified, which can be determined by the revised part number.

Note. Brake pads likewise must always be replaced on both sides of the axle.

Chamfer

Chips on the edge -arrow- of the brake rotor are caused by mechanical damage.

Scheme 10

The following are permitted

1. Maximum width / depth 2 mm.
2. maximum length = 10 mm
3. Maximum number of chips on the brake rotor = 3

If any of these criteria are exceeded, replace the brake rotor.

Replace the Brake Rotors on Both Sides of the Axle When

1. The brake rotors must replaced because they are worn
2. the replacement brake rotor has been technically modified, which can be determined by the revised part number.

Note. Brake pads likewise must always be replaced on both sides of the axle. If ceramic brake disc starts to show material break down on friction surface greater then ceramic brake discs must be replaced.

Nicks on Ceramic Brake Rotor

Replace the ceramic brake rotor if it has nicks on the friction surface with a surface greater than 1cm 2 -arrow-.

Scheme 11

Replace the Brake Rotors on Both Sides of the Axle When

1. The brake rotors must replaced because they are worn
2. the replacement brake rotor has been technically modified, which can be determined by the revised part number.

Note. Brake pads likewise must always be replaced on both sides of the axle.

Crack in Cooling Duct

If the ceramic brake rotor has a crack on the friction surface leading to or through the cooling channel -arrow-, the replace the ceramic brake rotor.

Scheme 12

CERAMIC BRAKE ROTORS, DETERMINING WEAR

Note. Ceramic brakes are installed only in the front.

Checking Threaded Connectors on the Brake Rotor Ring and Brake Rotor Cup

Ceramic Brake Rotor Identification on the Brake Rotor Cup

Scheme 13

1. Running Direction
2. Supplier
3. On-Going Brake Rotor Production Number
4. Audi Part Number NOTE: The Audi part number on the brake rotor is an example and will be different on each vehicle model.
5. Brake Rotor Date of Manufacture
6. Brake Rotor Minimum Permissible Thickness NOTE: The minimum permissible brake rotor thickness is different for each vehicle model.
7. New Brake Rotor and Cup Weight Checking Threaded Connectors on the Brake Rotor Ring and Brake Rotor Cup WARNING: The brake rotor ring and the brake rotor cup are attached to each other and must never be separated. Never loosen the threaded connector on the brake rotor cup. NOTE: The weight of a new brake rotor and cup will be different on each vehicle model.

Clean the Brake Rotor Before Measuring the Wear.

Note. The brake rotor vent holes must be free of brake dust and dirt. It may be necessary to use something suitable to clean the holes. Use not use force. Clean the brake rotor thoroughly with compressed air between the cooling channels and the vent holes.

Determining Brake Rotor Wear

1. 1. Check the brake rotor thickness.
2. 2. Check the wear indicators.

Always Replace the Brake Rotors on Both Sides of the Axle When

1. The brake rotors must replaced because they are worn.
2. the replacement brake rotor has been technically modified, which can be determined by the revised part number.

Note. If one of the three defined wear limit is reached, then the brake rotor can no longer be used. Replace the brake rotor. In this case, replace the brake rotors on each side of the axle. Brake pads likewise must always be replaced on both sides of the axle.

Check the Brake Rotor Thickness

Special tools and workshop equipment required

1. Use a commercially available caliper gauge or a micrometer gauge

The permissible minimum brake rotor thickness "min. Th." is engraved in the brake rotor cup.

Measure the brake rotor thickness three times on each wear indicator the circumference of the of the brake rotor -x-.

Scheme 14

Note. Check the brake rotor wear also using the wear indicators after determining dimension x = min. Th. +0.2 mm.

The brake rotor may no longer be driven once the permissible minimum thickness "min.Th." has been reached. Replace the brake rotor.

Note. Brake pads likewise must always be replaced on both sides of the axle. In this case, replace the brake rotors on each side of the axle.

Check the Wear Indicators

The wear indicators on the brake rotor friction surfaces are spaced 120 degrees apart from each other.

The wear indicators -arrow- have a different color to make it easier to recognize them.

Scheme 15

Note. There are three indicators on the front and back of the brake rotor for determining wear on a ceramic brake rotor. The following illustration shows a wear indicator that is OK.

Scheme 16

Note. The indicator will look like a dark, burned-out indentation when there is wear on the ceramic brake rotor. If one of the six indicators is completed burned out, then the brake rotor can no longer be driven. Replace the brake rotor. The following two illustrations show burned out wear indicators. In this case the brake rotor must be replaced.

Scheme 17

Note. In this case, replace the brake rotors on each side of the axle.

Scheme 18

Note. Brake pads likewise must always be replaced on both sides of the axle.

Checking Threaded Connectors On The Brake Rotor Ring And Brake Rotor Cup

BRAKES PR CODES

The following tables show the PR number code key. This is important in order to know the brake caliper/brake rotor and brake pad combination.

Note. Hairline cracks on brake rotor friction surfaces are often observed during brake repairs. Hairline cracks up to 10 mm long are not a technical flaw and are not cause for brake rotor replacement. Brake rotors with friction surfaces that have worn through should be replaced.

Note. Ceramic brakes are installed only in the front on this model. Hairline cracks on the friction surface on ceramic brakes occur during the manufacturing process and can be found on new brakes in different stampings. Hairline cracks on the friction surfaces are not a reason to exchange the ceramic brake rotors. Every brake rotor has a singed groove to recognize the wear limit. If the brake rotor friction surface the groove are worn down to an even level, the brake rotor wear limit has been reached.

The brake system installed in a vehicle is indicated on the vehicle data label by the relevant PR number -A and B-.

Scheme 19

Note. Hairline cracks on brake rotor friction surfaces are often observed during brake repairs. Hairline cracks up to 10 mm long are not a technical flaw and are not cause for brake rotor replacement. Brake rotors with brake pads that have worn through should be replaced.

BRAKES INSPECTION, FWD

The brake test is to be performed on a one-axle roller test stand.

The test speed must not exceed 6 km/h, otherwise, the brakes may lock up due to the roller start-up delay (EDL regulation).

Test stands approved by Audi meet these requirements.

BRAKES INSPECTION, AWD

Note. Test on a one-axle roller test stand for all-wheel drive vehicles.

During this test, the wheels of one axle are driven in opposite directions, to prevent delivering power to the other axle.

The test speed must not exceed 6 km/h, otherwise, the brakes may lock up due to the roller start-up delay (EDL regulation).

Test stands approved by Audi meet these requirements.

BRAKES INSPECTION, ELECTROMECHANICAL PARKING BRAKE

Test Sequence

Drive the vehicle with the rear wheel on the test rollers

Do not Switch off the Ignition

As soon as the rollers reach a speed between 3 km/h and 9 km/h, "T U V mode" is activated.

"Parking brake in diagnostic mode" appears in the instrument cluster when T U V mode is activated.

The "parking brake" display in the instrument cluster will start to blink

The EPB Functions as Follows

The brakes do not close once, but rather close a bit each time the button is pressed.

The tension is sufficient for measuring after a few steps.

Pay attention the display in the brake test stand.

One press on the button releases the brakes again.

Prerequisite for "T U V Mode"

Ignition on

Front wheels, speed greater = 0 km/h

Rear wheels, speed min. = 3, max. 9 km/h.

"Parking brake in diagnostic mode" appears in the instrument cluster when T U V mode is activated.

The "parking brake" display in the instrument cluster will start to blink