Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

2016 Subaru WRX BaseFACTORY OEM SERVICE PROCEDURE

Extension Case: Assembly

WARNING: This page is about a different variant/trim than selected.

Install the O-ring and plug.
NOTE: Use new O-rings.

Tightening torque:

25 N.m (2.5 kgf-m, 18.4 ft-lb)
Install the D-ring and O-ring to the transfer clutch piston.
NOTE:
- Use new D-rings and O-rings.
- Apply CVTF to the D-rings and O-rings of the transfer clutch piston assembly.
Insert the transfer clutch piston, spring retainer, return spring and clutch spring retainer.
Using the ST and a press, install the snap ring.
CAUTION: If the operation is performed with the dust cover installed, place a table between the extension case and the press table.

ST 18762AA001 COMPRESSOR SPECIAL TOOL

Fig 1: Installing Snap Ring Using Compressor Special Tool (ST18762AA001)
Courtesy of SUBARU OF AMERICA, INC.
Press-fit the dust cover into extension case.
Install the extension case oil seal to extension case.
ST 498057300 INSTALLER

Factory Service Tools

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.