Checking Rear PCCB Brake Discs

Information 

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Measurement markings on PCCB brake discs

> 465419 REMOVING AND INSTALLING REAR PCCB BRAKE DISC 

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Markings and values

• The validity of the measuring method using  > VAS 6813 - PCCB Brake Disc Tester is recognizable by the three markings and values offset by 120° on the brake disc hub -Arrows-  .
• > VAS 6813 - PCCB Brake Disc Tester is used to measure the damage to the carbon fibre-reinforced material. The lower the measured value, the more carbon fibres in the internal structure of the brake disc are damaged (wear caused by the effects of temperature)  .
• The markings consist of the measuring point numbers 1 to 3 -X- (figure shows measuring point number 1), the measurement marking -1- (line), the new value -2- and the wear value -3-  .
• If one of the three wear values -3- is reached or if the measured value is less than one of the three wear values, replace rear brake discs  .

Information 

• The brake disc temperature must be between  > Temperature 0 °C  and > Temperature 40 °C when taking measurements  .
• Check the tester before taking measurements and calibrate it if necessary. Follow the operating instructions provided by the equipment manufacturer! 
• Important for quick measurement: A metallic heat shield will lower the measured value  .

Information 

• The remaining service life of the brake disc can be estimated using the previously stored data and measured values recorded during service intervals/workshop visits based on the mileage  .
• The value is reduced by approx. two to five units per brake pad set (this does not apply for race track use and if brake pads not approved by Porsche are used)  .
• Carry out wear assessment on the brake discs and check the condition of the brake pads before and after every race track use (component temperatures are significantly higher)  .

Information 

When taking measurements, the tester must be positioned with the roller stops and underside of the device touching the entire surface of the brake disc -Arrows-  .

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Measuring procedure/tester (roller stops)

1. Use > VAS 6813 - PCCB Brake Disc Tester  to determine the wear condition. A differentiation is made between a quick measurement See "1.1 Quick measurement:" below  and an exact measurement See "1.2 Exact measurement:" below  .
   1. 1.1 Quick measurement:  Wheel fitted or removed, brake calliper fitted.

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      Quick measurement with wheel

      1. 1.1.1  Align laser beam -2-  with the measurement marking on the brake disc hub.

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         Tester on brake disc

      2. 1.1.2  Compare the values you read off with the wear value -3-  .

         If the wear value -3-  is reached or if the measured value is less than the wear value at a measuring point, carry out an exact measurement See "1.2 Exact measurement:" below 

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      Markings and values

      Information 

      Once removed, the brake calliper must not be placed closer than > Length 50 mm  from the back of the brake disc (see operating instructions supplied with the measuring equipment).

   2. 1.2 Exact measurement:  Wheel and brake calliper removed.
      1. 1.2.1  Remove rear brake calliper.

         > 474119 REMOVING AND INSTALLING REAR BRAKE CALLIPER

      2. 1.2.2  Align laser beam -2-  with the measurement marking on the brake disc hub.

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         Tester on brake disc

      3. 1.2.3  Compare the values you read off with the wear value -3-  .

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         Markings and values

      4. 1.2.4  If the wear value -3-  is reached or if the measured value is less than the wear value at a measuring point, replace rear brake discs.

         > 465419 REMOVING AND INSTALLING REAR PCCB BRAKE DISC 

      NOTE: NOTIFICATION 
      Work must not be carried out on the bores in the brake disc friction surface 

      • Risk of damage to brake discs 

        → Clean the bores on PCCB brake discs with high-pressure cleaning equipment if necessary. Observe the relevant environmental and safety regulations.

        → Do not machine the bores. Drilling or counter-sinking is not permitted.

2. Visual inspection of the brake disc friction surfaces for surface changes.
   1. 2.1  Check for build-up on brake disc friction surface.

      If there is a build-up on the pad, also check the following points:

      • Check ventilation (brake cooling):  All components are present, secured correctly and undamaged. Carry out repairs if necessary.
      • Check brake pad quality:  Use appropriate brake pads if the vehicle is driven on a racing circuit.
      • Check perforation bores for dirt and soiling:  The perforation bores in the brake discs must not be blocked. Clear them if necessary.
   2. 2.2  Check brake disc for flaking/fractures as a result of unusual usage conditions (e.g. stone chip damage).

      Flaking/fractures are only permitted up to a size of > Area 1 cm ²  !

   3. 2.3  If specified values are exceeded, replace the affected rear brake disc.

      > 465419 REMOVING AND INSTALLING REAR PCCB BRAKE DISC 

      Information 

      > 465419 REMOVING AND INSTALLING REAR PCCB BRAKE DISC 

      • If there is edge damage on the brake disc friction surfaces, only replace the affected brake disc  .
3. Check brake discs for edge damage:
   • Maximum permitted width/depth > Width/depth 2 mm 
   • Maximum permitted length > Length 10 mm 
   • Max. three damaged edges permitted

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   Edge damage