Synchro Ring and Gear Inspection

WARNING: This page is about a different variant/trim than selected.

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

Fig 1: Identifying Synchro Rings And Teeth Of Synchro Rings With Sign Of Cracks, Damage And Wear
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 2: Identifying Teeth Of Synchro Sleeve With Sign Of Good And Worn
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Inspect the synchro teeth on gear for scoring, cracks, and damage (A).

Fig 3: Identifying Synchro Teeth, Thrust And Cone Surface With Sign Of Cracks, Damage And Wear
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, making 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 (5th gear): 0.70- 1.49 mm (0.028- 0.058 in)

Standard (6th gear): 0.73- 1.44 mm (0.029- 0.056 in)

Service Limit: 0.4 mm (0.016 in)

Double Cone Synchro and Triple Cone

Synchro-to-Gear Clearance

Standard: (1st Gear)

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

0.70- 1.19 mm (0.028- 0.046 in)

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

0.70- 1.88 mm (0.028- 0.074 in)

(3): Outer Synchro Ring (B)-to-Gear (A)

1.12- 1.68 mm (0.044- 0.066 in)

Standard: (2nd Gear)

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

0.70- 1.19 mm (0.028- 0.046 in)

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

0.70- 1.88 mm (0.028- 0.074 in)

(3): Outer Synchro Ring (B)-to-Gear (A)

1.12- 1.68 mm (0.044- 0.066 in)

Standard: (3rd Gear)

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

0.68- 1.19 mm (0.027- 0.046 in)

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

0.48- 1.04 mm (0.019- 0.040 in)

(3): Outer Synchro Ring (B)-to-Gear (A)

0.95- 1.68 mm (0.037- 0.066 in)

Standard: (4th Gear)

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

0.70- 1.19 mm (0.028- 0.046 in)

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

0.50- 1.14 mm (0.020- 0.044 in)

(3): Outer Synchro Ring (B)-to-Gear (A)

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 4: Measuring Clearance Between Gear And Synchro Ring
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Synchro ring-to-gear clearance

Fig 5: Measuring Synchro Ring-To-Gear Clearance
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Double cone synchro and triple cone synchro-to-gear clearance

Fig 6: Measuring Double Cone Synchro And Triple Cone Synchro-To-Gear Clearance
Courtesy of AMERICAN HONDA MOTOR CO., INC.