Genuine BMW Z4 Brake Booster

BMW Z4 Brake Booster Parts Questions & Experts Answers

• Power Brake Booster
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  Q: What are the steps and considerations for removing and testing the power brake booster equipped with ABS and traction control on BMW Z4?

  A: On models equipped with ABS and Traction control or Dynamic stability control, removing the power brake booster requires the removal of the ABS/ASC+T or DSC control unit, and this task should only be performed by a BMW dealer or a suitably equipped specialist due to the need for special diagnostic equipment. To test the power brake booster, depress the brake several times to remove the vacuum, then start the engine while keeping the pedal firmly depressed; a noticeable give in the brake pedal should occur as vacuum increases. After allowing the engine to run for at least two minutes, the brake pedal should feel normal upon depression, with subsequent applications resulting in a firmer feel and decreased pedal stroke. If the booster does not operate, inspect the check valve; if it still fails, the unit must be replaced as repairs are not possible. For removal, new retaining nuts will be required upon installation. Begin by removing the master cylinder, disconnecting the vacuum hose from the check valve, loosening and removing the retaining screws of the driver's side lower dash panel, unhooking the brake pedal return spring, and removing the clevis pin securing the pedal to the pushrod. Next, loosen and remove the retaining nuts and take the power brake booster out of the vehicle. For installation, follow the reverse order of removal while checking the check valve sealing grommet for damage, transferring sound insulation material from the original booster if a new one is installed, ensuring correct engagement of the pushrod with the brake pedal, tightening the new retaining nuts to the specified torque, applying grease to the clevis pin, and securing it with the retaining clip. Finally, reinstall the master cylinder and brake-light switch, then start the engine to check for air leaks at the vacuum hose connection and verify the operation of the braking system.