Yamaha TDM850 User Manual page 97

2*58 Engine, clutch and transmission
32.4 Note the letter on each fork denoting its position
2 Remove the transmission output shaft (see
Section 30, Step 2).
3 If not already done when removing the
gearchange mechanism
components), remove the selector drum
retainer plate and the stopper arm return
spring, noting how the plate locates against
the flats on the selector fork shaft ends (see
Section 19).
4 Before removing the selector forks, note
that each fork is lettered for identification. The
right-hand fork has an 'R', the centre fork a
'C, and the left-hand fork an '!_' (see
illustration). These letters face the right-hand
side of the engine. If no letters are visible,
mark them yourself using a felt pen.
5 Support the selector forks and withdraw the
shafts from the casing, then remove the forks
(see illustrations 32.13b and a). Once
removed from the case, slide the forks back
onto their shafts in their correct order and way
round. On 1991 to 1995 TDM models and XTZ
models, note the spring fitted on the outside
of the left-hand fork.
6 Withdraw the selector drum from the
right-hand side of the casing (see illus-
tration 32.12).
32.13a Fit the centre fork (C) into the groove in the input shaft
pinion and locate the guide pin in its groove in the drum, then
slide in the shaft
Inspection
7 Inspect the selector forks for any signs of
wear or damage, especially around the fork
(external
ends where they engage with the groove in
the pinion. Check that each fork fits correctly
in its pinion groove. Check closely to see if the
forks are bent. If the forks are in any way
damaged they must be renewed.
8 Check that the forks fit correctly on their
shaft. They should move freely with a light fit
but no appreciable freeplay. Check that the
fork shaft holes in the casing are not worn or
damaged.
9 The selector fork shaft can be checked for
trueness by rolling it along a flat surface. A
bent shaft will cause difficulty in selecting
gears and make the gearchange action heavy.
Renew the shaft if it is bent.
10 Inspect the selector drum grooves and
selector fork guide pins for signs of wear or
damage. If either component shows signs of
wear or damage the selector(s) and drum
must be renewed.
11 Check that the selector drum bearing
rotates freely and has no sign of freeplay
between it and the casing. Renew the bearing
32.12 Slide the drum into the casing
if necessary (see Tools and Workshop Tips
(Section 5) in the Reference Section). Also
check that the neutral switch contact plunger
in the other end of the drum is free to move in
and out under spring pressure. If required,
remove the screw securing the contact plate
and remove the plunger and spring for
inspection or renewal (see Chapter 9).
Installation
12 Slide the selector drum into position in the
crankcase and position it so that the neutral
contact is against the neutral switch (see
illustration).
13 Refer to Step 4 for the correct location of
each fork (see illustration 32.4). Lubricate the
selector fork shafts with clean engine oil and
slide them into the crankcase, with the cut
end of the upper (single fork) shaft facing the
right-hand side, and the spring (where fitted)
in the lower shaft end facing the left-hand
side. Slide each shaft through its fork(s) and
into its bore, locating the guide pin on the end
of each fork into its groove in the drum as you
do (see illustrations).
14 Locate the stopper arm spring, then install
the selector drum retainer plate, making sure
32.13b Slide the shaft into the casing and through each fork in
turn - note the spring (arrowed)
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