Crankshaft
Figure 8
The rigid crankshaft
runs in six main bear-
ings and has ten coun-
terweights. It is made of forged va-
nadium-steel and is precipitation
hardened. The thrust bearing is placed
at the
fifth
main bearing from the front
to minimize both engine overall length
and crankshaft rear end movements.
FEM analysis has been used to op-
timize the crankshaft and the vibration
damper in combination with the en-
gine block under simulated dynamic
conditions, thus giving long service
life and good comfort.
The main and big end bearing surfaces
are induction hardened, with press-
rolled fillet radii for maximum fatigue
strength. The crankshaft nose in-
corporates two sets of splines, to drive
the oil pump and the vibration damper
hub. Theses splines, and the end
thread, are all rolled in a single opera-
tion, thus combining high strength
with cost-effective production. The
bearing surfaces are finally ground in
a data controlled point measurement
grinding machine, which stops ma-
chining automatically once the correct
dimensions have been obtained.
The main bearing shells are alumin-
ium while big-end shells are lead-
bronze.
Figure 10
Figure 9
Connecting rods and
pistons
Figure 9
The connecting rods are forged from
vandium alloy steel with an effective
length of 139.5 mm. High strength is
achieved through a precipitation hard-
ening process. The rods have a 1$0
degree thrust face against the crank-
shaft by virtue of the fact that the
bearing caps are 0.7 mm narrower
than the big end of the rods.
To achieve exact radial control be-
tween con rods and con rod caps,
these parts have ground serrated joints
employing yield-point tightening
bolts without nuts.
The connecting rod small and big
end weight is controlled and kept
within very narrow tolerances by
means of a special machining opera-
tion in order to minimize engine vi-
bration.
The pistons are made of aluminium
with cast-in steel expansion control.
The piston ring package consists of
two compression rings and one oil
scraper ring.
Camshaft drive Figure 10
Camshafts and water pump are driven
by the vibration damper hub on the
crankshaft by a toothed belt. For op-
timal engine performance it is nec-
essary to ensure extreme accuracy in
camshaft timing during assembly.
This is achieved by fixing the crank-
shaft and camshaft positions with spe-
cial locking tools while the drive is
fitted and adjusted. The belt is auto-
matically tensioned by means of a
spring-loaded piston assembly which
is hydraulically damped, to maintain
constant tension and compensate for
wear and temperature variations.
