Checking Rear Brake Discs (Minimum Thickness)

Information 

Normally, brake discs are used until the maximum wear dimension is reached.

>4650TW TECHNICAL DATA/BRAKE WEAR LIMITS 

Only in a few exceptional cases is it advisable to skim the brake discs (if there is deep scoring or corrosion of the friction surface). Only the brake disc dressing machines approved by Porsche AG may be used.

• Only "as new" brake discs may be reworked! 
• Only rework the brake discs symmetrically, evenly from both sides! 

As the pressure force of a brake piston on the brake pad varies in magnitude, different areas of wear arise on the friction surface. The brake disc can basically be divided into two areas of wear:

-A-  Outer and inner wear area.

-B-  Central wear area.

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Wear areas A and B

The central wear area -B-  is the area with the highest degree of wear.

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Wear area B

Measure the brake discs with a suitable micrometer at a minimum of three different places (-A, B, C-  ), offset by 120°.

Courtesy of PORSCHE CARS NORTH AMERICA, INC.

Measurement points for brake disc thickness