Test Values/Wear Limits - 981 GT4
Depending on the wear of cast iron brake discs, two condition criteria can make replacement necessary:
- Cracking in the holed (perforated) brake disc friction plates is in an advanced state .
- Minimum brake disc thickness is not retained due to wear (material erosion due to friction) .
| Location | Description | Type | Basic value | Tolerance 1 | Tolerance 2 |
|---|---|---|---|---|---|
| Pad thickness, front and rear | Measured value | approx. 12.0 mm | |||
| Pad thickness, front and rear (wear limit) | Measured value | 2 mm | |||
| Brake disc thickness, new (front) | Measured value | 34 mm | |||
| Brake disc thickness, new (rear) | Measured value | 30 mm | |||
| Brake disc minimum thickness after machining, front | Brake disc can only be reworked symmetrically, i.e. equally from both sides! | Measured value | 32.6 mm | ||
| Brake disc minimum thickness after machining, rear | Brake disc can only be reworked symmetrically, i.e. equally from both sides! | Measured value | 28.6 mm | ||
| Brake disc wear limit, front | Measured value | 32.0 mm | |||
| Brake disc wear limit, rear | Measured value | 28.0 mm | |||
| Peak-to-valley surface roughness of brake disc after machining (max.) | Measured value | 0.006 mm | |||
| Thickness tolerance of brake discs (max.) | Measured value | 0.02 mm | |||
| Lateral runout of brake disc (max.) | Measured value | 0.03 mm | |||
| Lateral runout of wheel hub (max.) | Measured value | 0.03 mm | |||
| Lateral runout of brake disc when installed (max.) | Measured value | 0.06 mm | |||
| Push rod play | Measured at brake pedal plate | Measured value | approx. 1 mm | ||
| Diameter of parking-brake drum | Diameter | 180 mm | |||
| Diameter of parking-brake drum, wear limit | Diameter | 181 mm | |||
| Width of parking-brake shoe | Measured value | 25 mm | |||
| Thickness of parking-brake pad | Measured value | 4.5 mm | |||
| Thickness of parking-brake pad, wear limit | Measured value | 2 mm |