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 TM 9-2815-226-34-1
3-14. REPAIR CRANKSHAFT
a. Buff all minor nicks and scratches with crocus cloth.
b. If inspection shows crankshaft is worn to a point where it must be reground and magnetic inspection shows it
suitable for regrinding, grind shaft to next standard undersize (table 3-1).
c. If crankshaft thrust face is worn, grind as necessary to accept larger thrust rings.
d. Fillet s add strength to crankshaft. Reducing fillet radii or undercutting subtracts material from that strength. If
fillets are larger than those specified, bearing shells may be squeezed and will quickly fail.
e. Grind width of journals to clean up basic face surface.
(1) If there are deep interruptions such as gouges or nicks that do not extend into fillets, smooth the edges with
crocus cloth.
(2) Maintain a limit of 0.030 in. (0.762 mm) over the maximum new crankshaft main bearing width specification
(3) The journal wall heights are not to be lowered to less than 0.010 in. (0.254 mm) from journal cheeks in
regrinding journal bearing widths.
(4) All fillet and bearing surfaces should have the same finish as a new crankshaft.
f. Crankshafts requiring "off-strike" grinding to clean up an unusually bad out-of-round crankpin can be ground off-
stroke a maximum of 0.020 in. (0.508 mm) over or under mean stroke dimension of new crankshaft
specifications. All crankpins must be reground to the degree of "off-stroke" required by the most out-of-round
crankpin.
g. Install the crankshaft gear.
WARNING
USE GLOVES TO PROTECTED HANDS. HANDLE GEAR WITH CARE.
CAUTION
DO NOT USE CUTTING TORCH TO HEAT GEAR. OVERHEATING OF GEAR WILL
REMOVE HARDNESS CAUSING EARLY FAILURE.
(1) Heat the gear with heating torch (not a cutting torch) to 400 F (204 C) for minimum of 1 hour.
(2) Lubricate the flange with grease and drive the gear onto the shaft with a piece of tubing.
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