General notes (Cooper 4-door hatchback and Cooper 2-door hatchback, 2020-2023)

The brake system is one of the most important safety systems on any car. It is therefore essential to act with utmost vehicle care when working on the brake system and to follow the instructions below.

• Ensure cleanliness and only use fluff-free cleaning cloths.
• Wash away or vacuum up brake dust, do not clear it away using compressed air. This dust is a health hazard.
• Ensure that no oils or grease enter the brake system: these substances would cause complete failure of the entire brake system.
• When cleaning brake components with brake cleaner (refer to applicable BMW parts catalogue), do not allow brake cleaner to get into the brake system.
• Even the most minute traces of brake cleaner must be avoided.
• Replace brake fluid at least every two years.
• Never reuse drained brake fluid.
• Always use BMW-approved brake fluid: BMW brake fluid DOT 4 with low viscosity, part# 83 13 0 443 026.
• Always dispose of brake fluid in approved receptacles .
• Do not allow brake fluid to drain into drain pipes, into the outside environment or into unsuitable facilities. This would create the risk of groundwater contamination since brake fluid is classed as a fluid that is hazardous to water.
• Do not allow brake fluid to come into contact with paintwork as this will destroy the paint.
• Brake fluid must not be allowed to remain on bare skin too long in order to avoid skin problems. Wash skin coated with brake fluid with water and soap.
• If brake fluid makes contact with eyes, immediately flush with large quantity of clean water and visit eye doctor.
• Brake pads:

  Brake pads must be replaced when the warning threshold value of the brake pad wear indicator is reached.

Refer to TECHNICAL DATA .

Brake pads must always be replaced on both sides of any axle.

The friction surfaces of the brake pads must not come into contact with oils or greases. The brake pads must be replaced if they are fouled by such substances.

In the case of rotation-dependent brake pads, make sure the arrow marking points in the direction of rotation of the brake disc for when the vehicle is driving forward. Brake pads with left/right markings must be fitted on the relevant side of the vehicle.

One-sided angled areas on the brake pads must be located on the blade contact side of the brake caliper for when the vehicle is driving forward.

• Brake discs:

  Brake discs must not be scored or cracked. Furthermore, minimum brake disc thickness, brake disc runout, parallelism and surface roughness of the friction surfaces must not exceed or undershoot the permitted values.

  Refer to TECHNICAL DATA .

  Always strip preservative off new parts before installation. With the rear brake rotors, also strip preservative off brake drum on parking brake.

• Brake drums:

  Brake drums must not be scored or cracked. Furthermore, the maximum drum inside diameter, radial runout and surface roughness of the friction surfaces must not exceed or undershoot the permitted values.

  Refer to TECHNICAL DATA .

  Always strip preservative off new parts before installation.

• Brake calipers:

  Only approved glycol-based pastes may be used for repairs on brake calipers.

  All shifting parts on the brake caliper must shift freely: note lubrication regulation (grease: ATE brake cylinder paste, BMW part# 83 19 9 407 854)..

• Brake lines and brake hoses must be correctly routed and must not abut with body or components in a way which would cause chafing.
• To prevent damage, release and tighten brake line couplings with a special brake line wrench only.
• The system must be bled each time any brake lines have been detached.
• All connection points must be checked for leaks.
• Only tighten down brake hoses on the front axle when wheels are in straight-ahead driving position.
• Close open connections on brake lines and individual components to prevent dirt from entering the brake system.
• Observe tightening torques when tightening down brake line screw connections.

Tightening torque, 34 32 1AZ .

The traction control system is basically maintenance-free.

However, be sure to adhere to the following:

• When carrying out welding work with electric welder, be sure to disconnect the connector from the electronic control unit (ignition turned off).
• During painting work, the control unit may be subjected for brief periods to loads of max. 95°C and for long periods (approx. 2 hours) to loads of max. 85°C.
• Tighten down the battery terminals completely.
• The brake lines on the hydraulic unit must not be mixed up; if necessary, mark them before they are removed and after completing repairs perform the mix-up check with the DIS Tester.