67
Repair Instructions
•
Grinding is carried out in the crankshaft grinding
machine to undersize according to the Workshop
manual “Technical data”.
•
It is very important that the hole fillet radii have
the correct dimensions.
R = 3.9 mm, and the correct form and surface
quality.
Crankshaft radii
Crankshaft, reconditioning
In general regrinding and realigning mean a shorter
lifetime. Therefore do not regrind unless there is good
reason for regrinding, measurement fault (wear, oval-
ness, conicity) or such serious surface damage that
grinding is not sufficient.
The crankshaft main and big end bearing journals can
be ground to 0.25 mm, 0.50 mm and 0.75 mm under-
size. See Workshop manual “Technical data” for infor-
mation about undersize dimensions.
Procedure when reconditioning
•
Align the crankshaft.
NOTE! Only align if really necessary, see “Inspec-
tion, crankshaft and bearings”.
•
Carry out crack check, see “Checking for cracks”.
•
Grind crankshaft if necessary, see next para-
graph and carry out new crack check.
•
Lap the crankshaft thoroughly after any grinding.
•
Clean off any grinding residue and other pollut-
ants. Flush and clean the oilways.
Grinding the crankshaft
A condition of achieving a satisfactory result when
grinding is to use the correct method. The following
grinding data is recommended:
Grinding wheel: Naxos 33A60 M6VK, alternatively
33A46 M6VK or Norton 23A60 M5VK alternatively
23A46 M5VK
Diameter, New disc Ø 36"–42" (914–1067 mm) ( the
disc can be used down to approximately Ø 720 mm).
Peripheral speed:
Grinding wheel .................................. 28–33 m/s
Crankshaft ................................. max. 0.25 m/s
Cooling: 3% oil emulsion (Soluble). It is important
that the cooling is powerful, ideally with flushing from
above and below.
The disc should be sharpened with a grinding diamond.
Peripheral dimension .................. 0.1 mm/revolution
Side measurement ...................... 0.2 mm/revolution
Cutting depth ................................... max. 0.03 mm
Lapping the crankshaft
The surface finish (profile depth Ra) of the crankshaft
flange, bearing surfaces and fillets is 2µm (7.874" x
10
-8
), with surface finish variation 0,5µm (1.969" x
10
-8
). This surface finish is achieved by lapping.
•
Lapping is done in the opposite direction to grin-
ding.
•
Apply cutting oil (such as VELOCITE 6) to the
crankshaft flange and bearing surfaces.
•
Lapping cloth, grit size 400.
•
Wash the shaft carefully after lapping is finished.
Use 95% industrial alcohol.
•
NOTE! Apply grease, VP part no. 1161447 to the
crankshaft flange.
Measure radius with a radius template. The
shape must follow the illustration “Crankshaft ra-
dii” on the previous page. Grinding notches and
sharp edges must not occur – these can cause
the crankshaft to break.
•
The center bearing journal grinding deserves spe-
cial attention when it comes to width measure-
ment for guide bearing “A”, in the illustration
“Crankshaft radii” on the previous page. Dimensi-
on, see “Workshop manual, Technical data”.
•
NOTE! Break sharp edges which may have for-
med at the oilways during the bearing grinding.
Use a grinding stone or an emery cloth.
•
Clean the shaft of any grinding residue and other
pollutants. Flush and clean the oilways.
