121
8
_07
Fig. 8.9
B1A1
A
D
C
A2
B2
B
ED0053029590
INFORMATION ABOUT OVERHAULING
8.4 Crankshaft
8.4.1 Dimensional check and overhauling
Wash the crankshaft thoroughly using suitable detergent.
Insert the pipe cleaner into all lubrication ducts B and blow
compressed air to free them completely from any dirt residues.
Check the state of wear and integrity of journals C and
connecting rod D.
Perform the operations described in Par. 9.3.1, perform the
operations described in Par. 9.3.6 - except Points 2, 4, 9
and 10).
Measure the crank pins A1 with a micrometer, and using a
dial gauge measure the internal diameter of the connecting
rod half-bearings A2.
Measure the main journals B1, with a micrometer, and using
a dial gauge measure the internal diameter of the crankshaft
half-bearings B2.
If the values described in Tab. 8.5 do not correspond, proceed
with grinding all gudgeon pins A1 e B1.
Gear A on the crankshaft is timed by a key, assembly of gear
A on the shaft occurs after heating at a stabilized temperature
of +180° C for 5 mins.
Important
• The crankshaft and connecting rod must be replaced every
time they are assembled to prevent seizure, as they are made
of special lead-free material.
• The MAX allowed value of wear for A1 e A2 is 0.120 mm.
• The MAX allowed value of wear for B1 e B2 is 0.120 mm.
• To grind the crankshaft, a decrease in diameter of the half-
bearings and connecting rod is provided for at 0.25 mm and
0.50 mm, to grind gudgeon pins A1 and B1, measure the
values of diameters A2 and B2 by assembling the decreased
half-bearings, define the diameter to grind of pins A1 and B1,
observing the clearance indicated in Tab. 8.5.
• Tab. 8.5 details the dimensional values of new components
only.
REF. DIMENSIONS (mm)
CLEARANCE
VALUE (mm)
A1 53.981 - 54.000
0.035 - 0.085
A2 54.035 - 54.066
B1 63.981 - 64.000
0.035 - 0.102
B2 64.035 - 64.083
Tab. 8.5 Connecting rod and journal diameter
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