BMW TSB #B340414
2003 BMW Z4
Affected Component: SERVICE BRAKES, AIR:DISC
- Diagnosis of Compound Brake System Complaints in M Vehicles: 1. Visible cracks are caused by high thermal stresses during rapid heating and cooling of the brake discs. Braking from high speed with cold brake components (less than 212 degrees F) increases the likelihood of cracks to form.