Ceramic Brake Disc, Determining Wear
Ceramic Brake Disc, Determining Wear
Checking threaded connectors on the brake disc ring and brake disc cup:
The brake disc ring and the brake disc cup are attached to each other and must never be separated. Never loosen the threaded connector on the brake disc cup.
Markings on the Ceramic Brake Disc Cup
1 Running Direction
2 Supplier
3 On-going Brake Disc Production Number
4 Audi Part Number
• The Audi part number on the brake disc is an example and will be different on each vehicle model.
5 The date the ceramic brake disc was made.
6 Minimum Permissible Thickness
• The minimum permissible brake disc thickness is different for each vehicle model.
7 New Ceramic Brake Disc and Cup Weight
Checking threaded connectors on the brake disc ring and brake disc cup:
The brake disc ring and the brake disc cup are attached to each other and must never be separated. Never loosen the threaded connector on the brake disc cup.
• The weight of a new brake disc and cup will be different on each vehicle model.
Determining Brake Disc Wear
• 1. Check the brake disc thickness
• 2. Weigh the brake disc
• 3. Check the wear indicators
Always replace the brake discs on both sides of the vehicle when:
• The brake discs must replaced because they are worn.
• The replacement brake disc has been technically modified, which can be determined by the revised part number.
If one of the three defined wear limit is reached, then the brake disc can no longer be used. Replace the brake disc.
In this case, replace the brake discs on each side of the vehicle.
Brake pads likewise must always be replaced on both sides of the vehicle.
Check the Brake Disc Thickness
Special tools, testers and auxiliary items required
• Use a commercially available caliper gauge or a micrometer gauge
The minimum permissible brake disc thickness "minimum Th." is engraved in the brake disc cup.
- Measure the brake disc thickness three times on each wear indicator the circumference of the of the brake disc - x -.
• When dimension x = minimum Th. +0.2 mm is reached, then the brake disc should also be weighed to determine the wear.
If the permissible minimum thicken "minimum Th." is reached, then the brake disc can no longer be driven. Replace the brake disc.
In this case, replace the brake discs on each side of the vehicle.
Brake pads likewise must always be replaced on both sides of the vehicle.
Weigh the Brake Disc
Special tools, testers and auxiliary items required
• Use a commercially available scale with an measuring exactness of up to +/- 1 gram.
- Remove the brake disc to weigh it.
Clean and dry the brake disc before weighing it.
Never clean the brake disc with water or any other fluid. This will make the measuring result incorrect.
• The vent holes on the brake disc must be free of brake dust and dirt. It may be necessary to use something suitable to clean the holes.
• Clean the brake disc thoroughly with compressed air between the cooling channels and the vent holes.
• Carefully lay the cleaned and dried brake disc on the scale.
- Carefully lay the cleaned brake disc on the scale.
The original weight of the new brake disc and cup is engraved in the cup.
The following value have been determined at the lowest limit value for brake disc loss in weight.
• Front brake disc: up to 200 grams weight loss from the original weight of the new brake disc.
• Rear brake disc: up to 120 grams weight loss from the original weight of the new brake disc.
• The limit values plus 20 grams are reached, then determine the brake wear by checking the wear indicators.
• If the limit values on the brake discs are reached, then replace the brake discs. The brake disc can no longer be driven. Replace the brake disc.
Always replace the brake discs on both sides of the vehicle when:
• The brake discs must replaced because they are worn.
• The replacement brake disc has been technically modified, which can be determined by the revised part number.
In this case, replace the brake discs on each side of the vehicle.
Brake pads likewise must always be replaced on both sides of the vehicle.
Check the Wear Indicators
The wear indicators on the brake disc friction surface are 120 degrees from each other.
The wear indicators - arrow - have a different color to make it easier to recognize them.
There are three indicators on the front and on the back of each brake disc.
When there is brake wear, the indicator will look like a dark, burned-out indentation.
If one of the six wear indicators is completed burned out, then the brake disc can no longer be driven. Replace the brake disc.
In this case, replace the brake discs on each side of the vehicle.
Brake pads likewise must always be replaced on both sides of the vehicle.
Checking threaded connectors on the brake disc ring and brake disc cup:
The brake disc ring and the brake disc cup are attached to each other and must never be separated. Never loosen the threaded connector on the brake disc cup.