STI Model

Check each part. <Ref. to INSPECTION , Rear Disc Brake Assembly.>
Clean the inside of the caliper body using brake fluid.
Preparation items:

Brake fluid: FMVSS No. 116, DOT3 or DOT4
Install the piston seal and the piston - disc brake.
1. Apply a coat of brake fluid to piston seal and install the piston seal to the groove inside caliper body.
2. Apply a coat of brake fluid to the piston sliding part of caliper body and the entire outer surface of the piston - disc brake.
  Preparation items:
  
  Brake fluid: FMVSS No. 116, DOT3 or DOT4
3. Apply a coat of grease to the piston boot and fit to the groove on the ends of piston - disc brake.
  Preparation items:
  
  Grease: An item contained in the pad kit or Nippon Grease NIGLUBE RX-2
4. Install the piston - disc brake to the caliper body.
CAUTION: Do not force the piston - disc brake into the sliding part of caliper body.

Fig 1: Installing Disc Brake Piston To Caliper Body
Courtesy of SUBARU OF AMERICA, INC.