You will need: ruler, key «at 13», pliers.
1. Press a brake pedal against the stop and measure distance from an overlay of a platform of a pedal to a floor.
Note. The ruler must be installed perpendicular to the plane of the floor.
2. Release the pedal and re-measure the distance from the pedal pad to the free floor. This distance should be 100–105 mm. The difference in size in two measurements is the full travel of the pedal, which should be 60–65 mm.
3. If the distance from the pedal pad to the floor does not correspond to that specified in paragraph 2, adjust it by changing the length of the pusher of the vacuum brake booster. Disconnect the push rod from the brake pedal (see «Replacing the vacuum booster»).
4. Loosen the tightening of the locknut 2 of the fork and, holding the pusher 3 from turning, rotate the fork 1 in the desired direction. One turn of the fork changes the position of the brake pedal by about 5 mm.
Note. For clarity, the work is shown on the removed vacuum amplifier. The manufacturer recommends removing the amplifier from the car to adjust the pedal position, however, with sufficient skills, adjustment can also be made directly on the car.
5. Check the free play of the brake pedal, for which move the pedal by hand until the pedal stops moving without resistance. Determine the value of the free play on the ruler, it should be 8-10 mm. The discrepancy between the free play and the specified value can be caused by the following reasons:
- increased play in the connection of the pusher fork of the vacuum booster and the pedal. This may be due to wear on the fork pin and holes in the fork and pedal;
- the distance from the pedal platform to the floor in the free state is incorrectly adjusted (see item 2, as well as dimension L in fig. 9.7);
- X size not adjusted correctly (see fig. 9.7) between the end of the adjusting bolt of the vacuum brake booster rod and the flange of its housing for attaching the master brake cylinder.
9.7. Adjusting dimensions of the vacuum brake booster: Х=22.3 mm; L=145.8 mm
6. If the pedal stroke is greater than the value given in paragraph 2, then this indicates the presence of air in the hydraulic brake drive or the wear limit of the brake pads, brake discs or drums. Bleed the air from the hydraulic (see «Bleeding the hydraulic drive of the brake system») or replace the brake pads (see «Replacing the brake pads of the brake mechanism of the front wheel»; «Replacing the brake pads of the brake mechanism of the rear wheel»), disks (see «Brake disc replacement») or drums (see «Removal and installation of a brake drum»).
Attention! If the pedal is pressed all the way down and held in this position gradually moves to the floor, this indicates a fluid leak from the hydraulic drive or a malfunction of the brake master cylinder. These malfunctions are very dangerous, so find the leak immediately and fix it or replace the brake master cylinder!