Superficial Cracks In Cooling Channel Lands; Cracks In Area Of Bolted Connection On Ceramic Brake Discs - Audi A8 2003 Workshop Manual

Due to the production process there already are relaxation cracks
(varying degrees) on the friction surface of the brake disc when it
is new.
Note
Relaxation cracks on a ceramic brake disc do not constitute a
technical problem.
The relaxation cracks may be clearly visible and vary in size.
2.2 Superficial cracks in cooling channel
lands
Superficial cracks in the cooling channel lands -arrow- are caused
during manufacturing.
Note
Superficial cracks in the cooling channel lands do not constitute
a technical problem on the ceramic brake discs.
2.3 Cracks in area of bolted connection on
ceramic brake discs
Checking area of bolted connection on friction ring and brake disc
hub:
WARNING
The brake disc ring and the brake disc hub are bolted together
and must NOT be separated. Do NOT slacken the bolted con‐
nection on the brake disc hub.
Ceramic brake discs must be renewed if there are cracks in the
area of the bolted connection of the brake disc hub extending into
the friction surface of the brake disc -arrows-.
The brake discs must be renewed on both sides of the axle if:
♦ renewal is necessary because of brake disc wear
♦ there has been a technical modification to the replacement
brake disc (indicated by changed part number).
Always renew brake discs on both sides of axle.
When doing so, always renew the brake pads on both sides of
the axle. ⇒ page 57
⇒ page 54
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Brake system - Edition 03.2013
⇒ page 63
Audi A8 2003 ➤
2. Assessment of ceramic brake discs
5