WARNING: This page is about a different car, the 2006 BMW 330xi, 2006 BMW 330i, 2006 BMW 325xi, and 2006 BMW 325i. However, it is still accessible from the selected car via links, so may be relevant.
TORQUE SPECIFICATIONS - BRAKE MASTER CYLINDER
Type
Thread
Tightening specification
Measure
1AZ Brake master cylinder to brake booster (vacuum)