Brake Booster: Installation

WARNING: This page is about a different car, the 2023 Subaru Ascent. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION:

Before performing service on the airbag module, always refer to "CAUTION" of "General Description" in "AIRBAG SYSTEM" service information . Ref. to AIRBAG SYSTEM>GENERAL DESCRIPTION>CAUTION .
When the electric booster assembly is replaced, be sure to perform the module registration.

Check and adjust the operating rod of the electric booster assembly.

Measure the length between the electric booster assembly mounting surface and clevis pin hole.

If it is not within the specification, loosen the lock nut and rotate the electric booster operating rod to adjust the rod length.

Specification L:

141.3 mm (5.56 in)

Courtesy of SUBARU OF AMERICA, INC.

Tighten the lock nut.
NOTE: Check the brake pedal height. When adjusting, also adjust the stop light switch assembly.

Tightening torque:

18 N.m (1.8 kgf-m, 13.3 ft-lb)

Install the master cylinder assembly. Ref. to BRAKE>MASTER CYLINDER>INSTALLATION .
Install the electric booster assembly.
CAUTION:
- Replace the clevis pin with a new part, and apply a thin coat of grease to the clevis pin.
  Preparation items:
  
  Grease: Shell Gadus S2 V220 or equivalent
- Replace gasket A and gasket B with new parts.
- Use a wobble extension for torque tightening to prevent interference with the column assembly steering.
Tightening torque:

18 N.m (1.8 kgf-m, 13.3 ft-lb)
Install the duct foot driver. Ref. to AIR CONDITIONER>HEATER DUCT>INSTALLATION>FOOT .
Install the knee airbag module. Ref. to AIRBAG SYSTEM>KNEE AIRBAG MODULE>INSTALLATION .
Install the cover LWR driver. Ref. to EXTERIOR/INTERIOR TRIM>INSTRUMENT PANEL LOWER COVER>INSTALLATION .

Install the pipe assembly front ABS.

Preparation tool:

Flare nut wrench

Crowfoot wrench

NOTE: If the work can be performed with the front and back sides reversed, it is also possible to use a 6-point crowfoot wrench.

Tightening torque:

TIGHTENING TORQUE SPECIFICATION

Calculation formula

T = 19 N.m (1.9 kgf-m, 14.0 ft-lb) xL1/(L1 + L2)

T: Reading of the torque wrench

L1: Effective length of the torque wrench

L2: Effective length of the crowfoot wrench

NOTE: If the effective length of the tool used is unknown, consult the manufacturer of the tool.

Courtesy of SUBARU OF AMERICA, INC.

(a)	Effective length of the crowfoot wrench (L2)
(b)	Effective length of the torque wrench (L1)
(c)	Center of the open end of crowfoot wrench
(d)	Center of drive square of the torque wrench
(e)	Center of the position where a force is applied by hand

Install the hose pressure suction. Ref. to AIR CONDITIONER>HOSE AND PIPE>INSTALLATION>HOSE .
Install the bracket harness electric booster.
Tightening torque:

18 N.m (1.8 kgf-m, 13.3 ft-lb)
Install the engine control module (ECM). Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>ENGINE CONTROL MODULE (ECM)>INSTALLATION .
Bleed air from the brake system. Ref. to BRAKE>AIR BLEEDING>PROCEDURE .
Connect the ground terminal to battery sensor. Ref. to REPAIR CONTENTS>NOTE>BATTERY .
Charge refrigerant. Ref. to AIR CONDITIONER>REFRIGERANT CHARGING PROCEDURE>PROCEDURE .
When the electric booster assembly is replaced, perform the module registration. Ref. to COMMON (DIAGNOSTICS)>UNIT REGISTRATION>OPERATION .
Perform a road test to make sure the brakes do not drag.