GM Service Manual Online
For 1990-2009 cars only
  1. Clean all the synchronizer parts in a suitable solvent. Air dry all the synchronizer parts.
  2. Inspect the synchronizer parts for the following conditions:
  3. • Burrs
    • Cracks
    • Chamfer for excessive wear
    • Free movement of the clutching sleeves on their hubs
    • Worn or damaged clutch teeth
    • Distorted springs
  4. Replace synchronizer parts that are worn or damaged.
  5. Replace a burred or nicked part that cannot be reconditioned by hand. Use a soft stone or a crocus cloth.


    Object Number: 38591  Size: SH
  6. Measure the gap between the vertical faces of the blocking ring teeth and the speed gear as follows:
  7. 4.1. Assemble the correct blocking ring with the correct speed gear.
    4.2. The blocking ring must be fully seated on the gear.
    4.3. Use a feeler gauge to measure the forward gear gap.
    4.4. Use a feeler gauge to measure the reverse gear gap.

    Measure the gap without the wave washer in between the blocking ring and the reverse gear.

    The nominal gap is 1.27-2.16 mm (0.050-0.085 in) for the 1st and 2nd gear.

    The nominal gap is 1.27-2.03 mm (0.050-0.080 in) for the 3rd, 4th, 5th and 6th gear.

    Replace the friction cones and blocker rings when the gap is significantly less than specified.