BRAKE FLUID
Note. Brake fluid is hygroscopic, meaning 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.
| WARNING | The rubber components of the brake system (boots, seals) do not tolerate mineral oil, gasoline, and cleaning agents! |
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
| WARNING | Distraction and testing equipment that is not secured properly increase the risk of an accident. The passenger airbag could be dangerous if it deploys during an accident. Operating testing equipment while driving is a distraction. Testing equipment that is not secured probably increases the risk of injury. Move the passenger seat as far back as possible. Only use the vehicle diagnostic tester. Testing equipment -1- must lie flat on the passenger's lap as shown in the illustration and must only be operated by that passenger. |
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).
| WARNING | If the test speed exceeds 6 Km/h the Torsen differential will be destroyed! |
Test stands approved by Audi meet these requirements.
ELECTRO-MECHANICAL PARKING BRAKE ON BRAKE TEST STAND
Test Sequence
Drive in vehicle with rear wheels on test rollers and do not switch ignition off.
Note. 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.
Note. "Parking brake in diagnostic mode" appears in the instrument cluster when T U V mode is activated.
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.
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.
Note. "Parking brake in diagnostic mode" appears in the instrument cluster when T U V mode is activated.
Depending on the model, the parking brake symbol with the line through it will light up.
| WARNING | A brake test stand with a regulated wheel set must be used on vehicles with all wheel drive. |
BRAKES
Applies to Hybrid Vehicles
| WARNING | Read and follow the High Voltage Electrical System General Warnings . |
The following tables show the PR number code key. This is important in order to know the brake caliper/brake disc and brake pad combination.
| Brake System | ||||
|---|---|---|---|---|
| Dual-circuit brake system with diagonal distribution and ABS, EBV, EDL, ASR, ESP, ECD and UP |
| Front Wheel Brakes | |||
|---|---|---|---|
| Production-relevant no. (Pr. no.) | 1LA | 1LJ | |
| Brake Caliper | FBC- 60 - 16" | FBC- 60 - 17" | |
| Brake disc ventilated | Diameter mm | 320 | 345 |
| Brake disc, thickness | Mm | 30 | 29.5 |
| Brake disc, wear limit | Mm | 28 | 27.5 |
| Brake caliper, piston | Diameter mm | 60 | 60 |
| Pad thickness with backing plate and dampening sheet | Mm | 19.2 | 19.2 |
| Brake pad wear limit with backing plate and dampening sheet | Mm | 7 | 7 |
| Rear Wheel Brakes | |||
|---|---|---|---|
| Production-relevant no. (Pr. no.) | 1KW | 1KE | |
| Brake Caliper | CII-43 EPB - 16" | CII-43 EPB - 17" | |
| Brake Rotor | Diameter mm | 300 | 330 |
| Unvented brake disc thickness | Mm | 12 | |
| Internally vented brake disc thickness | 22 | ||
| Brake disc, wear limit | Mm | 10 | 20 |
| Brake caliper, piston | Diameter mm | 43 | 43 |
| Pad thickness with backing plate and dampening sheet | Mm | 17.5 | 17.5 |
| Brake pad wear limit with backing plate and dampening sheet | Mm | 7 | 7 |
The brake system installed in a vehicle is indicated on the vehicle data label by the relevant PR number -A and B-.
Scheme 4
Note. Hairline cracks on brake disc 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 disc replacement. Brake discs with brake pads that have worn through should be replaced.