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Home >> Subaru >> 2015 >> WRX Limited, Automatic CVT Trans >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 13 (Manual Transaxle & Differential (TY85) (STI)) >> Front Differential Assembly >> Adjustment >> HYPOID Gear Backlash

HYPOID Gear Backlash

WARNING: This page is about a different variant/trim than selected.
  1. Attach the RH and LH side retainers.

    ST1 18630AA010 WRENCH COMPL RETAINER

    (RH SIDE)

    ST2 18630AA000 WRENCH ASSY (LH SIDE)

    NOTE:
    • Twist in the side retainer on the RH side a little further than that of the LH side.
    • WRENCH ASSY (499787000) can also be used.
  2. Attach the drive pinion shaft assembly, and affix with 5 bolts.
    NOTE: Use old gaskets and washers to prevent the mating surfaces of the housing from becoming damaged.

    Tightening torque: 

    50 N.m (5.1 kgf-m, 36.9 ft-lb) 

  3. Using the ST, loosen the differential side retainer RH, and twist in the differential side retainer LH until the hypoid driven gear just contacts the drive pinion.

    ST1 18630AA010 WRENCH COMPL RETAINER

    (RH SIDE)

    ST2 18630AA000 WRENCH ASSY (LH SIDE)

  4. Use the ST to turn the drive pinion shaft a few times.

    ST 18631AA000 HANDLE

    Fig 1: Turning Drive Pinion Shaft
    G05003490Courtesy of SUBARU OF AMERICA, INC.
  5. Repeat steps  3 and  4 until differential side retainer LH does not turn anymore. For differential side retainer RH, screw in until the inner race and outer race just comes into contact. This is the "zero" backlash state.
  6. Mark the mating positions of the left and right side retainers and the clutch housing.
    Fig 2: Identifying Left/Right Side Retainers Mark Mating Position
    G05003503Courtesy of SUBARU OF AMERICA, INC.
  7. Turn the back differential side retainer LH by 3 notches, and screw in the differential side retainer RH by 3 notches.
  8. Temporarily attach the LH side retainer lock plate.
  9. Turn the differential side retainer RH by 1.25 notches.
  10. Temporarily attach the RH side retainer lock plate.
    NOTE:
    • If the lock plate cannot be aligned, adjust the position toward the tightened side.
    • The notch on the lock plate moves by 0.5 notch if the lock plate is turned upside down when installed.
  11. Use the ST to fix the drive pinion shaft in place.

    ST 18621AA000 ADAPTER WRENCH

    Fig 3: Fixing Drive Pinion Shaft
    G05003521Courtesy of SUBARU OF AMERICA, INC.
  12. Install the SUBARU genuine axle shaft to the front differential left and right sides.

    Part No. 38415AA000 Axle shaft

  13. Move the axle shaft, and measure the hypoid gear backlash.

    ST1 498255400 PLATE

    ST2 498247001 MAGNET BASE

    ST3 498247100 DIAL GAUGE

    Hypoid gear backlash: 

    0.13 - 0.18 mm (0.0051 - 0.0071 in) 

    Fig 4: Measuring Hypoid Gear Backlash
    G05003522Courtesy of SUBARU OF AMERICA, INC.
  14. If the backlash is out of specified range, remove the left and right retainer lock plates and loosen RH side differential side retainer. Then, adjust the LH side differential side retainer by turning it, and attach the LH side retainer lock plate.
  15. Screw in the RH side differential side retainer until the inner race and outer race just come into contact.
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