Evaluating the cracks on the grey cast iron brake discs

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2005 Porsche 911, 2004 Porsche 911, 2003 Porsche 911, 2002 Porsche 911, and 2001 Porsche 911. However, it is still accessible from the selected car via links, so may be relevant.

The brake discs must be replaced (as a precautionary measure), if the perforation crack length is over 5 mm (as there is no mileage reserve in the event of further extreme load) and/or the friction plate rim is torn (less smooth braking and an increase in the likelihood that a disc will break)!
In the evaluation of damage, the following drawings must be used!

Corresponds to a disc exposed to above-average load.

Fig 1: Evaluating Cracks On Disc Exposed To Above-Average Load
Courtesy of PORSCHE OF NORTH AMERICA, INC.
- Need not be taken out of the vehicle!
In parts, perforation starter cracks are over 7 mm long. Conditions after shock braking 1,200 times (minimum desired: shock braking 200 times).

Fig 2: Evaluating Starter Cracks Over 7mm Long
Courtesy of PORSCHE OF NORTH AMERICA, INC.
- Brake disc can no longer be used!
Brake disc with torn friction plate rim -arrow-.

Fig 3: Identifying Brake Disc With Torn Friction Plate Rim
Courtesy of PORSCHE OF NORTH AMERICA, INC.
- Brake disc can no longer be used!