Main Shaft Inspection
Main Shaft InspectionReference: Main Shaft Disassembly: H27 Engine Model
^ Check clearance "a" between synchronizer ring and gear, width of index protrusion "b" in synchronizer ring, key slot width "c" in high and low speed synchronizer hub and each chamfered tooth of gear and synchronizer ring and replace with new one, if necessary. Also, check gear tooth.
Clearance "a" between synchronizer ring and gear (Main shaft) (1st, 2nd and 3rd)
Standard: 0.65 - 1.75 mm (0.026 - 0.069 inch)
Service limit: 0.5 mm (0.020 inch)
Width of index protrusion "b" (Main shaft)
Key slot width "c" (High and low speed synchronizer hub)
^ Measure width of high speed gear shift fork end a and groove width of high speed synchronizer sleeve "b" and then calculate clearance "c" as follows:
Clearance "c" = "b" - "a"
If clearance exceeds limit, replace fork and sleeve.
clearance "c" between fork and sleeve
Standard: 0.15 - 0.35 mm (0.006 - 0.014 inch)
Limit: 1.0 mm (0.039 inch)
^ Measure groove "a" of low speed gear shift fork and flange width "b" of low speed synchronizer sleeve and then calculate clearance "c" as follows:
Clearance "c" = "b" - "a"
If clearance exceeds limit, replace fork and sleeve.
Clearance "c" between fork and sleeve
Standard: 0.15 - 0.41 mm (0.006 - 0.016 inch)
Limit: 1.0 mm (0.039 inch)
^ Check diameter of main shaft (1) and thickness of main shaft (1) flanges as shown in the figure. If measured value is out of specification, replace main shaft (1).
Main shaft specifications (diameter and thickness)
^ Using V blocks (1) and dial gauge (2), check runout. If runout exceeds limit below, replace main shaft (3).
Main shaft runout
Limit: 0.015 mm (0.0006 inch)
^ Using cylinder gauge (1), check inside diameter of each gear. If its inside diameter exceeds specification, replace it.
Inside diameter (standard) of gear
1st gear: 46.015 - 46.040 mm (1.8116 - 1.8126 inch)
2nd gear: 53.015 - 53.040 mm (2.0872 - 2.0882 inch)
3rd gear: 44.015 - 44.040 mm (1.7329 - 1.7339 inch)
^ Check chamfered part of each sleeve for damage and excessive wear, and replace as necessary.
^ Check each synchronizer key and synchronizer spring and replace as necessary.
^ Check splined portions and replace parts if excessive wear is found.
^ Check 2nd gear (1) thrust clearance by using thickness gauge (2). If clearance is out of specification, repress-fit or replace defective part.
2nd gear thrust clearance
Standard: 0.10 - 0.25 mm (0.004 - 0.010 inch)
^ Check low gear (1) thrust clearance by using thickness gauge (2). If clearance is out of specification, repress-fit or replace main shaft bearing and 5th gear.
Low gear thrust clearance
Standard: 0.15 - 0.45 mm (0.006 - 0.018 inch)