Synchro Ring and Gear Inspection

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Inspect the synchro rings for scoring, cracks, and damage (A).

Fig 1: Identifying Synchro Rings For Scoring, Cracks & Damage Area
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Example of synchro ring teeth

Fig 2: Identifying Synchro Ring Teeth Condition
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Inspect the inside of each synchro ring (B) for wear. Inspect the teeth (C) on each synchro ring for wear (rounded off).
Inspect the teeth (A) on each synchro sleeve and matching teeth on each gear for wear (rounded off).

Fig 3: Identifying Teeth On Each Synchro Sleeve
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Example of synchro sleeve teeth and gear teeth

Fig 4: Identifying Synchro Sleeve Teeth & Gear Teeth Condition
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Inspect the synchro teeth on gear for scoring, cracks, and damage (A).

Fig 5: Identifying Synchro Teeth On Gear, For Scoring, Cracks & Damage
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Inspect the thrust surface (B) on each gear hub for wear.
Inspect the cone surface (C) on each gear hub for wear and roughness.
Inspect the teeth on all gears (D) for uneven wear, scoring, and cracks.
Coat the cone surface of each gear with MTF, and place its synchro ring on it. Rotate the synchro ring and make sure that it does not slip.
Measure the clearance between each gear (A) and its synchro ring (B) all around the gear. Hold the synchro ring against the gear evenly while measuring the clearance. If the clearance is less than the service limit, replace the synchro ring and gear.
Synchro Ring-to-Gear Clearance

Standard: 0.85-1.10 mm (0.033-0.043 in.)

Service Limit: 0.4 mm (0.02 in.)

Double Cone Synchro-to-Gear Clearance

Standard:

(1): Outer Synchro Ring (B) to Synchro Cone (C)

0.5-1.0 mm (0.02-0.04 in.)

(2): Synchro Cone (C) to Gear (A)

0.5-1.0 mm (0.02-0.04 in.)

(3): 0.95-1.68 mm (0.037-0.066 in.)

Service Limit:

(1): 0.3 mm (0.012 in.)

(2): 0.3 mm (0.012 in.)

(3): 0.6 mm (0.024 in.)

Fig 6: Measuring Clearance Between Each Gear & Synchro Ring Around Gear
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Synchro ring-to-gear

Fig 7: Identifying Synchro Ring-To-Gear Clearance
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Double cone synchro-to-gear

Fig 8: Identifying Double Cone Synchro-To-Gear Clearance
Courtesy of AMERICAN HONDA MOTOR CO., INC.