ARMY TM 9-2815-259-24
AIR FORCE TO 38G1-125-2
MARINE CORPS 09249A/09246A-24
If crankshaft is to be reground, use following recommended guidelines.
Crankshaft grinding should be done only by experienced personnel on
equipment capable of maintaining crankshaft size and finish specifications.
If undersize bearings are used, check bearing clearance after bearing caps
have been tightened to specified torque. If undersize bearings are too tight
and clearance is not within specifications, journals and bearing will be
wiped clean of all oil. This would result in premature wear of parts.
When grinding crankshaft, also grind fillet radii to specifications. This is
necessary to prevent stress risers in fillet areas during grinding.
Refer to Table 5-5 for undersize main and connecting rod bearings.
To maintain the correct end play, the two piece main bearing with three
piece thrust washer set can be used to replace the two piece flanged main
bearings if desired.
Compare crankshaft journal measurements taken during inspection and determine size which
journals are to be reground.
If one or more main or connecting rod journals requires grinding, then grind all of main journals or
all of connecting rod journals to same required size. Grind clockwise (opposite engine rotation).
All journal fillets radii must be free of any sharp grind marks or scratches. Fillet must blend
smoothly into journal and crank cheek. Radius may be checked with a fillet gage.
Care must be taken to avoid localized heating which often produces grinding cracks. Use coolant
generously to cool crankshaft while grinding. Do not crowd grinding wheel into work.
Polish or lap (counterclockwise) ground surfaces to specified finish. Reground journals will be
subject to excessive wear unless polished smooth.