Checking front PCCB brake discs (wear assessment): General

Two conditions of criteria can make replacement necessary depending on the wear of perforated brake discs:

1. Surface changes in the brake disc friction surfaces at advanced stage.
2. Brake disc minimum thickness is not attained due to wear (material erosion due to friction).

   In practice, both forms of disc erosion usually occur.

   Only in seldom cases (for long-term race driving brake loads / very high temperature fluctuations in the friction surfaces), the surface changes can proceed so quickly that a premature disc change has to be performed.

1. Visual inspection of the surfaces of the brake disc friction surfaces 
   NOTE:

   • The friction surface changes occur due to material fatigue as a result of extremely high thermal load. These disc temperatures which occur above all in racing operation cause a progressive material fatigue.
   • Effects on driving: The surface change worsens the smoothness of braking, decreases the disc strength and increases the brake pad wear and therefore makes a precautionary parts replacement necessary.

   The following illustrations (PCCB brake disc wear appearance) are to be used.

   PCCB brake disc wear appearance 

   1. Friction area surface after normal brake load in street use operation.
      Fig 1: Identifying Friction Area Surface After Normal Brake Load In Street Use Operation

      Courtesy of PORSCHE OF NORTH AMERICA, INC.
      • No replacement necessary!
   2. Friction area surfaces after a long run and occasional higher load.
      Fig 2: Identifying Friction Area Surfaces After A Long Run

      Courtesy of PORSCHE OF NORTH AMERICA, INC.
      • Replacement not yet necessary!
   3. End of service life of friction area surface or after highest load on a racing track.
      Fig 3: Identifying End Of Service Life Of Friction Area Surface

      Courtesy of PORSCHE OF NORTH AMERICA, INC.
      • Replace brake discs in the case of connected friction surface damage > 1 cm² .
2. Checking brake discs for minimum thickness 
   NOTE:

   • For perforated brake discs, the minimum thickness must always be measured on the inner or outer friction surface trace.
   • Brake disc thickness/wear limit: Max. 0.5 mm total wear permissible. Refer to the technical data for the new dimension and other dimensions Refer to TECHNICAL DATA/BRAKE WEAR LIMIT - TURBO WITH PCCB  or TECHNICAL DATA/BRAKE WEAR LIMIT - GT2 .
   • Measure the brake disc thickness dimension -X-  , with a suitable micrometer screw or a brake disc gauge in the area of the inner and outer friction surface traces -arrow-. 
     Fig 4: Measuring Point For Brake Disc Thickness Dimension

     Courtesy of PORSCHE OF NORTH AMERICA, INC.
3. Checking brake discs for edge damage 
   NOTE:

   • Irrespective of wear, a brake disc change can be necessary on the brake disc friction surfaces due to edge damage!
   • In this case, only one brake disc can be replaced if the friction area surface of the other PCCB brake disc is in order.
   Fig 5: Identifying Edge Damage On Brake Disc

   Courtesy of PORSCHE OF NORTH AMERICA, INC.

   The following criteria applies to edge damage assessment:

   • Max. permissible width/depth = 2 mm!
   • Max. permissible length = 10 mm!
   • Max. 3 damaged edge areas permissible!