Crankshaft and Connecting Rod Assembly.
The dismantling, bverhauf and
assembly of this unit
is
a job that
is
normally undertaken by the dealer,
or
at the works.
If the owner wishes to carry out the work, he must have
a
certain amount of
mechanical abil~ty and a good workshop.
Dismantling. Grip the bottom end of the flywheel in the vice and carefully mark
each rod so that they can be replaced in exactly the same position relative to the
cranks and the connecting rod cap to the rod itself. Unscrew the two nuts recurin,
each rod and remove the rods from the cranks. Replace the cap to the rods for
the time being.
Identify the cranks to the flywheel and then remove the six bolts
and nuts when the assembly can be parted.
Inspection and Identification. Wash
all
parts thoroughly and examine the
bearing surfaces.
New.
Crank big-end journal size
:
Earlier pattern 1.4360" (3.6484 cms.)
1.4365" (3.6497 cms.)
Currsnt models 7.6235" (4.1237 cms.)
1.6240" (4.1 250 cms.)
Connecting rod big-end size
:
Earlier pattern 1.4370" (3.6510 cms.)
1.4375" (3.6522 cms.)
,,
,
Current models 1.6250" (4.1 275 cms.)
1.6255" (4.1 289 cms.)
Connecting rod sma!l end (All)
...
...
0.6885" (1.7488 cms.)
0.6890" (1.7501 cms.)
......
Gudgeon pin size (All)
...
...
0.6882" (1.7480 cms.)
0.6885" (1.7488 cms.)
Connecting rod end float (All)
...
...
0.0290" (0.737 mm.)
0.0320" (0.81
3
rnm.)
Light score marks on the crank big-end journals can be carefully eased down with
smooth emery but after this operation the parts must be carefully washed again.
If the cranks are scored, rhe connecting rod big-ends will also show similar signs,
these should be carefully removed by using
a
scraper and if necessary
a
minute amount
of metal can be removed from the mating surfaces of the cap and rod to enable the
rod
to
be refitted to
its
original clearances. If any metal
is
removed from the mating
surfaces, the bearing will have to be re-bedded by remov'qg
all
high spots (use
engineers' marking blue on the journal bearing to detect higri ipots) with a scraper.
Remember, the maximum amount of white metal in the connecting rod cap
is
0.025"
(0.635 mrn.). This operation should only be done by a mechanic who
is
fully con-
versant with this type of engineering procedure.
If the damage
is
beyond repair, service re.ground cranks and connecting rods to
fit
can be obtained from
a
dealer in the following UNDERSIZES
:-
Cranks
...
.,.
...
...
...
...
....
0.010"-0.020''
Connecting rods
...
...
...
... ...
...
0.01 0"-0.020''
The small end bush wear can be detected by inserting the gudgeon pin into the bush.
If in good condition the pin should be
a
smooth working
fit
in the buih, no rock
being in evidence. To replace the bush, press out the old one and
at
the same time
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