TM 5-4320-302-146-17.CONNECTING ROD ASSEMBLY (CONT)Location/ItemActionRemarks23. Big-end bearingsa.Replace if bearings are excessively worn, out-of-tolerance, out-of-round, or show any scoring,pitting, flaking, etching, or signs of overheating.Replace if bearings show any bright spots on theback or outside surfaces. Replace with nominalor undersized bore bearings or oversized wallthickness bearings as appropriate for the size ofthe corresponding crankpin on the crankshaft.b.Install new big-end bearings in connecting rodonly if necessary. Follow procedure describedin step 13. Tighten and retighten hex bolts inaccordance with procedure described in step 10.Remeasure bearing bore in accordance withstep 14. Measurements for nominal or under-sized bore should correspond correctly to thosein the chart on page 6-132. The nominal big-end bearing bore, for example, should be2.0488 to 2.0501 inches (52.040 to 52.073 mm).However, if the bore measures an additional0.0008 inch (0.020 mm) on either side oftolerance limits, the connecting rod and big-endbearing would still be acceptable forreinstallation. The tolerance limits would thenbecome 2.0480 to 2.0509 inches (52.020 to52.093 mm) and the connecting rod and big-endbearing would be acceptable for further use.This would also apply to any of the undersizedbore bearings where the acceptable tolerancelimits would also be increased by an additional0.0008 inch (0.020 mm) on either side. If big-end bearing bore measurements are still outsidethe extended tolerance limits, the connectingrod must be replaced. This would includereplacement of small end bush, big-end bearing,bearing cap, pin, and hex bolts.6-137
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