Genuine Audi A3 Brake Booster

Audi A3 Brake Booster Parts and Q&A

• Booster Assembly
  1K1-614-106-A
  Q: How to test and replace the Brake Booster servo unit on Audi A3?

  A:

  In order to test the brake booster, press the footbrake a few times to deplete the vacuum, then upon starting the engine, press the pedal to the floor; one should have a feel of the brake pedal giving in as the vacuum fills in supply. Let the engine run for a minimum of two minutes and then turn it off. When the brake pedal does not get hard when stepped on the first time but becomes stiffer every time the brake pedal is used, then the brake booster is working well. In case it does not work, examine the brake booster non-return valve and, in diesel models, the vacuum pump. If the brake booster does not work satisfactorily, then it should be replaced because it cannot be repaired. The brake booster may be removed by first disassembling the master cylinder, followed, where necessary, by the heat shield and the vacuum hose of the sealing grommet. Uncouple the wiring to the brake booster vacuum sensor (where fitted), remove the retaining circlip, and dislodge the sensor. With LHD models and a manual transmission, the gearchange cables are to be disconnected, and the gearchange support bracket is to be unbolted and tied up. Eliminate the lower side of the driver facia panel and the lower side of the dash panel. On models produced prior to the end of 2005, the brake light switch is found to be located on the pedal bracket and is to be removed. When installed, loosen the retaining screws and unscrew the connection plate between the brake and clutch pedals, and also take away the air duct and cover so that the brake booster mounting nuts can be accessed. Attach a special tool or a suitable alternative to release the brake pedal from the brake booster pushrod off the ball with a special tool in place of the plastic lugs, which are tough. Loosen the nuts holding the brake booster to the bulkhead and then push the unit out of place, retrieving the gasket where used. Clearing of the inlet manifold may be required on some of the RHO models. To refit, inspect the vacuum hose sealing grommet to see if it is damaged and fit a replacement gasket to the rear of the brake booster and re-fit it in the engine compartment. Make sure that the brake booster pushrod is properly seated in the brake pedal, press the pedal on the pushrod ball, and reassemble and tighten the mounting nuts to the required torque. Install the connecting plate, air duct, and cover back in place where necessary, and on models built prior to late 2005, replace the brake light switch again. Refit the facia trim panels, and on LHO models with manual transmission, refit the gearchange cables and support cable. Ease the vacuum hose firmly back in the correct position, ensuring that the sealing grommet has not been shifted around, and reattach the heat shield and, where necessary, the vacuum sensor and wiring. Lastly, install the master cylinder again, and on RHO models, install the inlet manifold again, should it be missing. When it is completed, start the engine and inspect for air leaks at the vacuum hose-to-brake booster connection and the functioning of the braking system.