911 Targa (996) F6-3.6L (2004)
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NOTE:
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As opposed to smooth brake discs, by which the minimum thickness is measured in the middle of the disc (effective friction radius), in the
case of perforated brake discs, the minimum thickness must be measured on the inner or outer friction surface track, -arrows- whichever is
most worn.
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Brake disc thickness/wear limit; Max. 2.0 mm total wear permissible. Refer to the technical data for the new dimension and other
dimensions.
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Measure the brake disc thinnest point with a suitable micrometer screw, at one of the two smooth friction rim zones -arrows- (at the
most worn friction rim area).
Example of wear
The drawing shows the typical grooved wear profile -3 arrows- of a perforated grey cast iron brake disc, which has been used to the wear
limit, under tough conditions i.e. constant operation mode (test operation mode).
Notes On Bedding In New Brake Pads
In the case of the perforated (holed) friction plate, the contact pattern of newly installed brake pads adapts more quickly to the wear profile of the
previously operated brake disc than is the case with smooth brake discs.
In general, the following applies: new brake pads must be worn in (bedding-in period), their optimum braking effect is therefore not reached until after a
few hundred kilometers. The slightly reduced braking effect must be compensated for by increased pressure on the brake pedal. The same also applies
after a brake disc change.
Checking Rear Brake Discs (Wear Assessment)
Checking Rear Brake Discs (Wear Assessment)
Includes:
1. Visual inspection for cracks and evaluating cracks.
2. Checking brake discs for minimum thickness.
General
The condition of the parts can make replacement necessary under two criteria, depending on the wear of perforated brake discs:
1. Cracking in the holed (perforated) friction plate is in an advanced state.
2. Brake disc minimum thickness is not attained due to wear (material erosion due to friction).
In practice, both forms of disc erosion occur.
