TM 5-3895-346-14
CRANKSHAFT
ENGINE OVERHAUL
the axis of the shaft) starting from either the critical fillet locations or the connecting rod journal oilholes as
shown in Fig. 5. Replace the crankshaft when cracks of this nature are found.
Crankshaft Grinding
In addition to the standard size main and connecting rod bearings, 0.002, 0.010, 0.020, and 0.030 inch
undersize bearings are available.
NOTE
The 0.002 inch undersize bearings are used only to compensate for slight wear on
crankshafts on which regrinding is unnecessary.
If the crankshaft is to be reground, proceed as follows:
1. Compare the crankshaft journal measurements taken during inspection with the dimensions in Table 1 and
Fig. 6 and determine the size to which the journals are to be reground.
Figure 5. Crankshaft Fatigue Cracks
Figure 6. Dimensions of Crankshaft Journals - In-Line
Engine
2. If one or more main or connecting rod journals require grinding, then grind all of the main journals or all of
the connecting rod journals to the same required size.
3. All journal fillets in the inline crankshafts must have a 0.130 to 0.160 inch radius between the crank cheek
and the journal and must not have any sharp grind marks (Fig. 7). The fillet must blend smoothly into the
journal and the crank cheek and must be free of scratches. The radius may be checked with a fillet gage.
4. Care must be taken to avoid localized heating which often produces grinding cracks. Cool the crankshaft
while grinding, using coolant generously. Do not crowd the grinding wheel into the work.
5. Polish the ground surfaces to an 8-12 rms finish. The reground journals will be subject to excessive wear
unless polished smooth.
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