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Wear assessment by checking thickness of brake disc > < Cracks leading to cooling channel

A4 Mk2

Assessment of wear on ceramic brake discs
Assessment of wear on ceramic brake discs
On these models (8E and 8H), ceramic brakes are fitted only at the front.
Checking area of bolted connection on friction ring and brake disc hub:
  WARNING
Brake disc ring and disc brake hub are bolted together and must NOT be separated. Do NOT slacken bolt connection on disc brake hub.
Designation of ceramic brake disc on disc brake hub
   
1 - Direction of rotation
2 - Supplier
3 - Serial production number of brake disc
4 - Audi part number
  Note
The Audi part number of the brake disc is an example and can vary depending on the vehicle type and model
5 - Production date of ceramic brake disc
6 - Permissible minimum thickness of brake disc
  Note
The minimum permissible thickness of the brake disc differs depending on the type of vehicle.
7 - Weight of new ceramic brake disc with disc brake hub
Checking area of bolted connection on friction ring and brake disc hub:
  WARNING
Brake disc ring and disc brake hub are bolted together and must NOT be separated. Do NOT slacken bolt connection on disc brake hub.
  Note
The weight of the new brake disc with hub differs depending on the type of vehicle.

To assess the brake disc wear, proceed as follows:
t  1. Wear assessment by checking thickness of brake disc
t  2. Wear assessment by weighing brake disc
t  3. Wear assessment on basis of wear indicators
   
1. Wear assessment by checking thickness of brake disc → Chapter
Thickness of brake discs in permissible range → brake disc OK
Brake disc thickness in critical range min. Th + 0.2 mmValue at or below limit
↓↓↓↓
Further wear assessment by weighing brake discRenew brake disc
↓↓----------
2. Wear assessment by weighing brake disc → Chapter
Weight of brake disc in permissible range → brake disc OK
Weight of brake disc in critical range (less than 20 g to maximum permissible weight loss)Value at or below limit (front axle: up to 200 g below initial weight of new brake disc)
↓↓↓↓
Further wear assessment on basis of wear indicatorsRenew brake disc
↓↓----------
3. Wear assessment on basis of wear indicators → Chapter
None of the six wear indicators fully worn out → brake disc OK
----------One of the six wear indicators fully worn out
---------↓↓
----------Renew brake disc

Always renew brake discs on both sides of axle if:
t  the brake discs have to be renewed due to wear.
t  there has been a technical modification to the replacement brake disc (indicated by changed part number).
If one of the three wear limits defined below has been reached, do NOT continue using the brake disc. The brake disc must be renewed.
In this case, always renew the brake discs on both sides of the axle.
When doing so, always renew the brake pads on both sides of the axle.
   

Wear assessment by checking thickness of brake disc > < Cracks leading to cooling channel