M/T Synchro Ring and Gear Inspection

1.Inspect the inside of each synchro ring (A) for wear.Inspect the teeth (B) on each synchro ring for wear (rounded off).

 

2.Inspect the teeth (C) on each synchro sleeve and matching teeth on each gear for wear (rounded off).

 

3.Inspect the thrust surface (D) on each gear hub for wear.

 

4.Inspect the cone surface (E) on each gear for wear and roughness.

5.Inspect the teeth on all gears (F) for uneven wear, scoring, galling, and cracks.

6.Coat the cone surface of each gear (E) with oil, and place its synchro ring on it. Rotate the synchro ring, making sure that it does not slip.

7.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 (0.028-0.059 in.) 
6th gear: 0.73-1.44 mm (0.029-0.057 in.) 
Service Limit: 0.4 mm (0.016 in.) 

Double Cone Synchro-to-Gear Clearance
Standard: 
(1): Outer Synchro Ring (B) to Synchro Cone (C)
0.70-1.19 mm (0.028-0.047 in.)
 
(2): Synchro Cone (C) to Gear (A)
0.50-1.04 mm (0.020-0.041 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.) 

Triple Cone Synchro-to-Gear Clearance
Standard: 
(1): Outer Synchro Ring (B) to Synchro Cone (C) 
 1st gear: 0.70-1.19 mm (0.028-0.047 in.) 
 2nd gear: 0.70-1.19 mm (0.028-0.047 in.) 
(2): Synchro Cone (C) to Gear (A) 
 1st gear: 0.45-1.14 mm (0.018-0.045 in.) 
 2nd gear: 0.60-1.88 mm (0.024-0.074 in.) 
(3): Outer Synchro Ring (B) to Gear (A) 
 1st gear: 1.12-1.68 mm (0.044-0.066 in.) 
 2nd gear: 0.87-1.82 mm (0.034-0.072 in.) 
Service Limit: 
(1): 0.3 mm (0.012 in.) 
(2): 0.3 mm (0.012 in.) 
(3): 0.6 mm (0.024 in.)