CNC Middle Case 01-07 mod

When a pre-2007 Subaru OEM middle casing suffers structural failure or cracking due to high torque loads, replacement options are limited due to global market unavailability of early-generation components. This technical constraint requires a conversion to the readily available 2008+ casing architecture. However, these later-generation STi factory casings are produced without an integrated oil pump mechanism and, in specific variations, lack the structural provisions for DCCD (Driver's Controlled Center Differential) harness integration.

To restore active internal lubrication and maintain differential compatibility post-failure, X Shift Gearboxes provides an advanced in-house CNC modification. This engineering solution adapts a brand new, genuine OEM middle casing as a full replacement for Subaru WRX STi models 2001-2007.

OEM middle cases for modification:

• 32114AA180 - model years 2008–2015
• 32114AA310 - model years 2015+
  • improved version - dual locking mechanism (dual plungers) for safer and more solid guiding of the main shift rod

Integrating this modified casing architecture addresses thermal management and drivetrain stability requirements under competitive racing conditions:

• Active oil lubrication: Restoring the internal pump functionality permits the integration of external fluid cooling loops. This configuration significantly lowers operating oil temperatures and protects the racing gearset and bearings from thermal shear.

• DCCD Compatibility: The modification allows for a complete conversion to an active DCCD configuration - big improvement in case of consistent torque distribution and maximum mechanical grip.

• Electrical Integration: To ensure a fully sealed and functional conversion, a genuine OEM DCCD wiring harness (Part No. 24031AA441) can be supplied.

There are two configuration options: 

• Sourcing of a brand new 08+ casing from X Shift - execution of the full CNC machining program, and international dispatch

• Machining of a customer-supplied 08+ middle casing - all supplied components must be thoroughly cleaned and verified to be free of structural damage or prior fatigue cracks.

This is a direct replacement and full compatibility of the newer middle case 08+ for the older 01-07 type:

• Customer must install the OEM pump internals and possibly the DCCD differential from the 01-05 type (can also be fitted with the newer DCCD differential 06-08 with oil ring)

• Type 01-05 uses a shorter 1/2 shift rod. It is necessary to replace the rod with a longer one from the 06+ version when installing the casing 08+ into the OEM gearbox! X Shft dogbox/sequential kit can be supplied with a longer rod.