Fig. 15–23. HP-2 front support: 1 – protective cap; 2 – bleed nipple; 3 – caliper bracket housing; 4 – sealing ring; 5 – piston; 6 – protective cover
The HP–2 front caliper parts are shown in Fig. 15–23.
Note: Both parts of the caliper bracket housing are connected by bolts with an internal shaped recess and cannot be disassembled. If the protective covers of the guide pins are damaged, they must be replaced with new ones.
The sealing rings are removed using a mounting wedge and installed by hand.
Clean the caliper from dust and dirt, but do not inhale the dust that rises.
Secure the caliper in a vice. To remove the piston, apply low-pressure air to the brake cylinder through the brake hose connection hole. On the side of one piston, install a special piston pressing device that will hold the piston in place, and on the side of the second piston, install a wooden block.
Fig. 15–24. Using a wedge to remove a seal from a caliper cylinder groove
Remove the wooden block and carefully remove the piston. Carefully, so as not to damage the cylinder walls, remove the seal from the groove of the caliper cylinder with a mounting wedge or a flat-head screwdriver blade as a lever (Fig. 15–24).
Check the condition of the cylinder and piston. If there are scratches, grooves, wear or pitting, replace the piston and cylinder. Regardless of the condition, replace the rubber seals.
Wash all parts in methylated spirits or clean brake fluid and wipe them dry.
Fig. 15–21. Location of installation of the protective cover on the caliper piston
Apply a thin layer of grease G 052 150 A2 to the sealing ring and piston (see Fig. 15–21).
Install the dust boot onto the piston so that the inner diameter of the boot fits into the piston groove.
Fig. 15–25. Using a special device to install the working edge of the dust cover into the support
Place the piston opposite the caliper cylinder and, using a special tool, insert the working edge of the dust cover into the caliper until it locks into place (Fig. 15–25).
Using a special tool or a hammer handle, press the piston into the caliper cylinder.
After installing the piston, blow air into the cylinder and fill it with fresh brake fluid.
If it is necessary to replace the second piston, repeat the operations for removing and installing the caliper piston; when removing the piston, install a wooden block on the side of the second piston.