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Home › Subaru › 2021 › WRX STI › Repair and Diagnosis › Transmission › Manual Trans › Manual Transaxle & Differential (TY856) › Main Shaft Assembly › Installation

Main Shaft Assembly: Installation

  1. Adjust the 3rd-4th and 5th-6th fork rods. Refer to MANUAL TRANSMISSION AND DIFFERENTIAL(6MT) (TY85)>SHIFTER FORK AND ROD>ADJUSTMENT .
  2. Rotate the reverse idler sub gear in the arrow direction by two teeth, and secure it with a wire.
    G13648102Courtesy of SUBARU OF AMERICA, INC.
  3. Attach the driven gear assembly to the 1st-2nd shifter fork assembly.
    G13648103Courtesy of SUBARU OF AMERICA, INC.
  4. Attach the main shaft assembly to the 3rd-4th shifter fork, and assemble to the driven gear assembly.
    G13648104Courtesy of SUBARU OF AMERICA, INC.
  5. Attach the 5th-6th shifter fork assembly to the main shaft assembly.
    G13648105Courtesy of SUBARU OF AMERICA, INC.
  6. Attach the reverse shifter fork assembly to the reverse idler gear assembly.
    G13648106Courtesy of SUBARU OF AMERICA, INC.
  7. Install the reverse idler gear assembly.
    G13648107Courtesy of SUBARU OF AMERICA, INC.
  8. Install the thrust bearing of the driven gear assembly.
  9. Push on the shifter forks, main shaft assembly, driven gear assembly and reverse idler gear assemblies, to attach to the adapter plate all at once.
    NOTE: A helper is required to perform this work.
  10. As necessary, remove the wire used to secure from the reverse idler gear.
  11. Install the shift accent plunger, check ball spring, new O-ring and check plugs.

    Tightening torque: 

    25 N.m (2.5 kgf-m, 18.4 ft-lb)

    G13648108Courtesy of SUBARU OF AMERICA, INC.
  12. Install the check ball, check ball spring, new O-ring and check plugs.

    Tightening torque: 

    25 N.m (2.5 kgf-m, 18.4 ft-lb)

    G13648109Courtesy of SUBARU OF AMERICA, INC.
  13. Install the bolt and a new gasket holding the reverse idler shaft.

    Tightening torque: 

    25 N.m (2.5 kgf-m, 18.4 ft-lb)

  14. Use a screwdriver to shift to the 4th gear position.
  15. Install the reverse idler holder.
  16. Install the oil guide B.

    Tightening torque: 

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

  17. Install the striking rod.
  18. Install the transmission case. Refer to MANUAL TRANSMISSION AND DIFFERENTIAL(6MT) (TY85)>TRANSMISSION CASE>INSTALLATION .
  19. Install the selected main shaft snap ring and washers.
  20. Install the center differential. Refer to MANUAL TRANSMISSION AND DIFFERENTIAL(6MT) (TY85)>CENTER DIFFERENTIAL>INSTALLATION .
  21. Install the transfer driven gear. Refer to MANUAL TRANSMISSION AND DIFFERENTIAL(6MT) (TY85)>TRANSFER DRIVEN GEAR>INSTALLATION .
  22. Install the extension case. Refer to MANUAL TRANSMISSION AND DIFFERENTIAL(6MT) (TY85)>EXTENSION CASE>INSTALLATION .
  23. Install the neutral position switch, back-up light switch and harness. Refer to MANUAL TRANSMISSION AND DIFFERENTIAL(6MT) (TY85)>NEUTRAL POSITION SWITCH>INSTALLATION . Refer to MANUAL TRANSMISSION AND DIFFERENTIAL(6MT) (TY85)>BACK-UP LIGHT SWITCH>INSTALLATION .
  24. Install the manual transmission assembly to the vehicle. Refer to MANUAL TRANSMISSION AND DIFFERENTIAL(6MT) (TY85)>MANUAL TRANSMISSION ASSEMBLY>INSTALLATION .
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