Volvo Penta Aquamatic 250C Workshop Manual page 14

7. Then press on the bearings (9) and the bearing
boxes (25) on the gear (8).
NOTE: When compressing, protect the taper so that it
is not deformed.
8. Adjust start adjustment with the "Forward" gear.
Should the previously removed gears be used, it is
important that the "Forward" and "Reverse" gears are
not confused when fitting. For an outboard drive with
standard rotation, i.e. propeller with a left-hand thread,
the "Forward" gear is the lower gear. An outboard
drive with reversed rotation has the upper gear as
"Forward" gear.
9. In order to obtain a clear picture of the tooth con-
tact pattern, smear the teeth on the input gear and
meshing gear with a thin coating of marking paint.
10. First fit the "Forward" gear in the gear housing (1).
Start by inserting 0.2 mm (0.008") shims under the
bearing box (25).
11. Fit the attaching plate with part No. 884285 for the
upper gear housing in a vice.
12. Fit the upper gear housing on tool 884285 so that
the bearing coincides with the corresponding recess
in the tool.
13. Fit the input gear with 0.3 mm (0.012") shims un-
der the double bearing box (11).
NOTE: The guide pin in the double bearing box should
face downwards.
14. Fit the clamp ring together with sufficient shims so
that the ring actually presses in the double bearing
box (there must be clearance between the gear hous-
ing and the clamp ring).
15. Rotate the gear in its correct direction of rotation
(clockwise) while braking hard the gear at the same
time by pushing against the taper on the gear with a
suitable rod, see Fig. 6. The marking paint on the
gears is removed on the surfaces where they mesh
and this gives a picture of the tooth contact pattern
and its position.
16. Measure the backlash by using a rocker arm indi-
cator, see Fig. 7. The backlash should be 0.10–0.20
mm (0.0039–0.0079").
17. Remove the gear assembly and compare the con-
tact pattern on the teeth with the pattern shown in Fig.
8 which is on ideal pattern.
NOTE: The contact pattern is practically rectangular
and, on the driving side, should be on the centre of the
teeth vertically but rather more towards the toe than
the heel. If the input gear is moved from the outside
inwards, the contact pattern moves from a low posi-
tion to o high position on the gear. If the contact pat-
tern is too high on the gear teeth, the input gear
should be moved outwards and if it is too low, the in-
put gear should be moved inwards.
12
18. When the correct tooth contact and backlash have
been obtained for the "Forward" gear, adjust the "Re-
verse" gear in a corresponding way.
NOTE here that only the shims under the reverse gear
must be moved since otherwise it will alter the num-
ber of shims required under the "Forward" gear.
Fig. 6
Fig. 7
Fig. 8