Attention! Be sure to replace all pads, even if only one is worn out. If the brake pads are reinstalled, they must be marked before removal.
When you press the brake pedal, the brake fluid presses on the piston, moving it out of the cylinder. Piston seal under the action of significant pressure on the piston moves with the cylinder. However, since a part of the piston seal is fixed in a groove whose shape matches that of the seal, the top of the seal is deformed in the direction of piston movement.
When the brake pedal is released, the pressure of the brake fluid decreases, and the elastic force created by the deformation of the piston seal returns the piston to its original position.
As the brake pads wear and the gap between the brake disc and the pads increases, the piston moves even more, thereby keeping the gap the same. The shape of the stuffing box can later change, but since the inside of the stuffing box is fixed in the groove of the cylinder, the amount of deformation remains the same. The piston moves further to close the gap. As the piston returns to its original position, the gap between the brake disc and the brake linings is maintained at the required level.
Pic. 6.7. Camry front wheel disc brakes: 1 - brake disc; 2 - fastening bolt; 3 - flexible hose; 4 - gasket; 5 - guide pin; 6 - cover of the guide pin; 7 - cuff; 8 - spring ring; 9 - bleed valve