FixVault

Front Differential Assembly: Inspection

Repair or replace the differential gear in the following cases:

  1. BEVEL PINION GEAR BACKLASH 

    Measure the backlash between bevel gear and pinion. If it is not within specifications, install a suitable washer to adjust it.

    NOTE: Be sure the pinion gear tooth contacts adjacent gear teeth during measurement.

    ST1 498247001 MAGNET BASE

    ST2 498247100 DIAL GAUGE

    1. Standard backlash: 0.13 - 0.18 mm (0.0051 - 0.0071 in) 
    Fig 2: Measuring Backlash Between Bevel Gear & Pinion
    G00916542Courtesy of SUBARU OF AMERICA, INC.
  2. HYPOID GEAR BACKLASH 
    1. Insert the SUBARU genuine axle shaft into the left and right side retainer holes. (TURBO model)

      ST 38415AA000 AXLE SHAFT

    2. Set the ST1, ST2 and ST3. Insert the needle through transmission oil drain plug hole so that the needle comes in contact with the tooth surface at a right angle and check the backlash.

      ST1 498247001 MAGNET BASE

      ST2 498247100 DIAL GAUGE

      ST3 498255400 PLATE

      1. Backlash: 0.13 - 0.18 mm (0.0051 - 0.0071 in) 
      Fig 3: Inserting Needle Through Transmission Oil Drain Plug Hole
      G00916543Courtesy of SUBARU OF AMERICA, INC.
    NOTE: If the backlash is outside specified range, adjust it by turning the holder in right side case.
  3. TOOTH CONTACT OF HYPOID GEAR 

    Check the tooth contact of hypoid gear as follows: Apply a uniform thin coat of red lead on both tooth surfaces of 3 or 4 teeth of the hypoid gear. Move the hypoid gear back and forth by turning the transmission main shaft until a definite contact pattern is developed on hypoid gear, and judge whether face contact is correct. If it is inaccurate, make adjustment. Refer to ADJUSTMENT  , Front Differential Assembly.

    • Tooth contact is correct.
      Fig 4: Checking Tooth Contact Of Hypoid Gear
      G00916544Courtesy of SUBARU OF AMERICA, INC.