Crankshaft (8-Cylinder); Crankshaft Main Bearings (8-Cylinder) - Jeep 1979 CJ-5 Technical & Service Manual

1B-64 ENGINES
CRANKSHAFT ••
The crankshaft Is counterweighted and balanced inde-
pendently. The component parts of the crankshaft as-
sembly are individually balanced, then the complete
assembly is balanced as a unit. Service replacement
dampers, crankshafts, flywheels and torque converters
may be replaced without rebalancing the assembly.
There are five main bearings and four connecting rod
journals. The end thrust is controlled by No. 3 main
bearing.
The rear main bearing oil seal is protected from exces-
sive oil by a slinger which is a machined part of the
crankshaft.
NOTE: Mark the torque converter and converter flex-
plate prior to removal Install in the same position dur-
ing assembly.
-Removal i r Replacement
Replace the crankshaft if it is damaged beyond re-
conditioning. Use the procedures outlined under Cylin-
der Block to remove or replace the crankshaft.
Crankshaft Eni Plif Measurement
Crankshaft end play is controlled at the No. 3 main
bearing which is flanged for this purpose.
(1) Attach dial indicator to crankcase adjacent to
No. 3 main bearing.
(2) Set dial indicator push rod on face of adjacent
counterweight (fig. 1B-104).
Fig. 1 B-104
Crankshaft End Play Measurement
(3) Pry crankshaft fore and aft.
(4) Read dial indicator. End play is difference be-
tween high and low readings.
(5) If end play is outside of specifications, inspect
crankshaft thrust faces for wear. If no wear is apparent,
replace thrust bearing and check end play. If end play is
still outside of specifications, replace crankshaft.
NOTE: When replacing the thrust bearings, pry the
crankshaft fore and aft to align the thrust faces of the
bearings before final torque tightening.
Crankshaft lain Baariip
The main bearings are steel-backed aluminum-tin
with overplated copper-lead as an optional lining. The
main bearing caps are numbered 1 through 5, front to
rear, with an arrow to indicate forward position. The
upper main bearing inserts are grooved. The lower in-
sert surfaces are smooth.
Each bearing is select fitted to its respective journal to
obtain the desired operating clearance. In production,
the select fit is obtained by using various-sized color-
coded bearing inserts as shown in the Main Bearing
Fitting Chart. The bearing color code appears on the
edge of the insert.
NOTE: Bearing size is not stamped on production
inserts.
The main bearing journal size is identified in produc-
tion by a color-coded paint mark on the adjacent cheek
toward the flanged (rear) end of the crankshaft except
for the rear main journal. The paint mark for the rear
main journal is on the crankshaft rear flange.
Use the Bearing Fitting Chart to select proper bearing
inserts to obtain the specified bearing clearance. The
correct clearance is 0.0015 to 0.0020 inch (0.038 mm to
0.051 mm) on No. 1 through No. 4 main bearings and
0.0023 to 0.0027 inch (0.058 mm to 0.069 mm) for the rear
main bearing.
When required, use different sized upper and lower
bearing inserts as a pair. Use a standard size upper
insert in combination with a 0.001-inch undersize lower
insert to reduce clearance by 0.0005 inch or 1/2
thousandth of an inch (0.013 mm).
Example:
Insert Correct Incorrect
Upper
Standard Standard
Lower
0.001-inch
undersize
0.002-inch
undersize
7 0 2 4 2
NOTE: When servicing upper and lower inserts of dif-
ferent sizes, install undersize inserts either all on the top
(upper) or all on the bottom (lower). Never use bearing
inserts with greater than 0.001-inch difference in pairs.