Grinding of the crankshaft
To achieve satisfactory results in connection with grind-
i
ng the following factors should be taken into considera-
tion:
1.
Grind the crankshaft in a crankshaft grinding ma-
chine to the undersize as per "Technical data". Sur-
face fineness 1.6 Z (
VVV
) for bearing races
(B, Fig. 73) and recess radius are achieved by rub-
bing with emery cloth No. 400.
Fig. 73. Checking of recess radius
2.
I
t is very important that the recess radius is the cor-
rect size.
Recess radius:
- At main and big-end bearing journals,
"A" = 3 ± 0.25 mm (.1181 ±.0098 in)
- At oil holes, "C" = min. 2 mm (.0787 in),
max. 5 mm (.1968 in).
Grinding hacks and sharp edges must be avoided
since these can give rise to crankshaft fracture.
3.
Clean the crankshaft well from grinding residue and
other impurities. Flush and clean the oil channels.
I
nspection of main and big-end bearings
Check the main and big-end bearing cups and the front
crankshaft busing. Replace worn bearings or those with
damaged bearing surfaces.
I
nspection of front crankshaft bushing
Check the bearing clearance between the big-end jour-
nal and bushing. Use a cylinder indicator and a micro-
meter.
Fig. 74. Checking of bearing clearance
1.
Measure the bushing's inner diameter at points 1
and 2 as per Fig. 72 on page 46. Measure in two
directions ("A" and "B") at each point.
2.
Measure the bearing journal's outer diameter and
calculate the bearing clearance (difference be-
t
ween the previous measurement and the bearing
j
ournal's max. diameter).
Max. bearing clearance: 0.2 mm (.0078 in).
Replace the bushing if the clearance exceeds the per-
missible value. Where necessary the crankshaft can be
ground to an appropriate undersize and the bushing
can be replaced with a corresponding oversize.
Note:
Check the bearing clearance again before the
crankshaft is fitted if it has been re-ground.
Engine body
4
7
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