Synchronizers Cleaning and Inspection

If you are servicing this transmission for a shifting concern such as clash, hop out of gear, or block-out in a particular gear, the following hardware must be replaced as a set for the gear in question. Adjoining gears do not need to be serviced unless necessary:

• Main gear in question - for example 2nd, 3rd
• Synchronizer assembly, slider sleeve assembly
• Blocker ring assembly
• Shift fork inserts, pads

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:
   • Burrs
   • Cracks
   • Hicks
   • Chamfer for excessive wear
   • Free movement of the clutching sleeves on their hubs
   • Worn or damaged clutch teeth
   • Distorted springs
3. Replace synchronizer parts that are worn or damaged.

   Replace a burred or nicked part that cannot be reconditioned by hand. Use a soft stone or a crocus cloth.

Fig 1: Measuring Gap Between Blocking Ring & Speed Gear
Courtesy of GENERAL MOTORS COMPANY
NOTE:

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

4. Measure the gap between the vertical faces of the blocking ring teeth and the speed gear as follows:
   1. Assemble the correct blocking ring with the correct speed gear.
   2. The blocking ring must be fully seated on the gear.
   3. Use a feeler gauge to measure the forward gear gap.
   4. Use a feeler gauge to measure the reverse gear gap.

      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 less than specified.