Test Values/Wear Limits For Cayenne 17" Brake System (V6)
Information
Depending on the extent of wear on cast iron brake discs, two condition criteria can make replacement necessary:
- Formation of cracks at advanced stage on the brake disc friction surfaces.
- Minimum brake disc thickness is not retained due to wear (material erosion due to friction). → WM 465002 CHECKING FRONT BRAKE DISCS (WEAR ASSESSMENT) → Checking rear brake discs (wear assessment)→ WM 465302 CHECKING REAR BRAKE DISCS (WEAR ASSESSMENT)
| Location | Description | Type | Basic value | Tolerance 1 | Tolerance 2 |
|---|---|---|---|---|---|
| Pad thickness, front | Wear limit 2 mm | approx. 10.5 mm | |||
| Pad thickness, rear | Wear limit 2 mm | approx. 11.5 mm | |||
| Brake disc thickness, front | New | 32 mm | |||
| Brake disc thickness, rear | New | 28 mm | |||
| Brake disc minimum thickness after machining, front | Only 'as new' brake discs may be reworked! Only rework the brake disc symmetrically, evenly from both sides! | 31.6 mm | |||
| Brake disc minimum thickness after machining, rear | Only 'as new' brake discs may be reworked! Only rework the brake disc symmetrically, evenly from both sides! | 27.6 mm | |||
| Brake disc wear dimension, front | 30 mm | ||||
| Brake disc wear dimension, rear | 26 mm | ||||
| Peak-to-valley surface roughness of brake disc after machining, max. | 0.006 mm | ||||
| Thickness tolerance of brake discs after machining, max. | 0.02 mm | ||||
| Lateral runout of brake disc, max. | 0.03 mm | ||||
| Lateral runout of wheel hub, max. | 0.02 mm | ||||
| Lateral runout of brake disc when installed, max. | 0.06 mm | ||||
| Pushrod play | Not adjustable | ||||
| Parking brake (foot-operated parking brake) | Drum brake acting mechanically on both rear wheels | ||||
| Parking-brake drum Ø | Wear limit 211 mm | 210 mm | |||
| Brake shoe width | 30 mm | ||||
| Brake pad thickness | Wear limit 1 mm | 3 mm |
Possible complaints
- Damage due to lack of use (rusting). This causes vibrations in the steering wheel, noises and brake pedal pulsation.
- Brake disc becomes distorted as a result of serious driving.
- Too much lateral runout when new brake discs are fitted on dirty or distorted wheel hubs.
Procedure
- Check brake disc for cracks, minimum thickness, lateral runout, thickness tolerance, flatness and surface roughness.
- The brake disc must only be reworked symmetrically, i.e. evenly from both sides! Observe the operating instructions for the disc brake dressing machine!
If necessary, (depending on the actual brake disc thickness and the brake disc wear limit) machine the brake disc using one of the disc brake dressing machines approved by Porsche.