TM 5-4320-302-14
6-20. CRANKSHAFT ASSEMBLY (CONT)
Location/Item
Action
Remarks
11. Main bearing
a. Make sure bush is seated properly in crank-
bush
case. Inspect for damage or excessive wear.
Measure bearing bush bore with precision
micrometer at points 1 and 2 and along axis
A and B.
b.
The bore of a normal size bearing bush
should measure 2.5216 to 2.5232 inches
(64.050 to 64.089 mm). If measurements
are outside the tolerance limits, replace
main bearing bush with one of the normal
or undersized bore (oversized wall thick-
ness) bearing bushes listed below:
NORMAL
NOMINAL
INSIDE DIAMETER AND
WALL THICKNESS AND
UNDERSIZES
OVERSIZES
inches
inches
BEARING BUSH
(millimeters)
(millimeters)
Normal inside diameters
2.5216 to 2.5232
0.0974 to 0.0976
and
Nominal wand
(64.05 to 64.089)
(2.475 to 2.480)
Nominal wall thickness
2.5020 to 2.5035
0.1073 to 0.1075
First undersize
(63.55 to 63.589)
(2.7254 to 2.730)
2.4823 to 2.4838
0.1171 to 0.1173
Second undersize
(63.05 to 63.089)
(2.975 to 2.980)
2.4626 to 2.4641
0.1270 to 0.1272
Third undersize
(62.55 to 62.589)
(3.225 to 3.230)
6-169
