Wear Assessment By Weighing Brake Disc - Audi A8 2003 Workshop Manual

♦ Rear brake disc: Up to 120 g weight loss from initial weight of
new brake disc.
Note
If the weight loss is only 20 g within these limits, additionally check
the wear of the brake disc according to the wear indicators.
If the weight loss has reached or exceeded these limits, the brake
discs must be renewed. It is no longer permissible to use these
brake discs. The brake disc must be renewed.
Always renew brake discs on both sides of axle if:
♦ the brake discs have to be renewed because of wear.
♦ there has been a technical modification to the replacement
brake disc (indicated by changed part number).
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.
3.4 Wear assessment by weighing brake
disc
Brake disc with minimum weight stamped on hub:
Special tools and workshop equipment required
♦ Commercially available scales with a tolerance of ± 1 g
Procedure
– Remove front brake disc for weighing.
– Remove rear brake disc for weighing.
Note
Depending on the version, the minimum permissible weight for a
used brake disc is stamped on the brake disc hub. The disc must
be renewed when the weight of the disc is less than or equal to
the indicated minimum weight. Always renew brake discs on both
sides of the axle.
• The brake disc must be cleaned and dry before it is weighed.
Caution
Do NOT clean the brake disc with water or other fluids as this
will falsify the results.
Note
The brake disc ventilation drillings must be completely free of
♦
dirt. Clear out carefully with a suitable tool if necessary.
Thoroughly blow out the brake discs with compressed air (in‐
♦
cluding the area between the cooling channels and ventilation
drillings).
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permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability
with respect to the correctness of information in this document. Copyright by AUDI AG.
Audi A8 2003 ➤
Brake system - Edition 03.2013
3. Assessing degree of wear on ceramic brake discs
13