Technical data wear limit - 911 Carrera 4

Depending on the wear of cast iron brake discs, two condition criteria can make replacement necessary:

1. Cracking in the holed (perforated) brake disc friction plates is in an advanced state.
2. Brake disc minimum thickness is not attained due to wear (material erosion due to friction).
   BRAKE SYSTEM WEAR LIMIT TECHNICAL DATA - 911 CARRERA 4
   
   

   Designation		Note, dimensions	Wear limit
   Pad thickness	front	approx. 12.0 mm	2 mm
   	rear	approx. 10.5 mm	2 mm
   Brake disc thickness, new	front	28 mm
   	rear	24 mm
   Minimum brake disc thickness (1) after machining (1)	front	26.6 mm (1)(1)
   	rear
   Brake disc wear limit	front		26.0 mm
   	rear		22.0 mm
   Peak-to-valley surface roughness of the brake disc after machining, max.		0.006 mm
   Thickness tolerance of the brake discs, max.		0.02 mm
   Lateral runout of the brake disc, max.		0.03 mm
   Lateral runout of the wheel hub, max.		0.03 mm
   Lateral runout of the brake disc when installed, max.		0.06 mm
   Pushrod play (measured at the brake pedal plate)		approx. 1 mm
   Parking brake (handbrake)		Drum brake acting mechanically on both rear wheels
   Parking brake drum		180 mm	181 mm
   Brake shoe width		25 mm
   Brake pad thickness		4.5 mm	2 mm
   (1) The brake disc must only be reworked symmetrically, i.e. from both sides evenly.