Servicing - wsm STW37 Workshop Manual

STW34, STW37, STW40, WSM

[4] SERVICING

Backlash between Clutch Disc and Clutch Shaft
1. Mount the clutch disc onto the propeller shaft.
2. Hold the propeller shaft so that it does not rotate.
3. Slightly move the disc and measure the displacement around
disc edge.
4. If the measurement exceeds the allowable limit, replace clutch
disc.
Displacement around
Allowable limit
disc edge
Clutch Disc Wear
1. Measure the depth from clutch disc surface to the top of rivet at
least 10 points with a depth gauge.
2. If the depth is less than the allowable limit, replace the disc.
3. If oil is sticking to clutch disc, or disc surface is carbonized,
replace the clutch disc.
Disc surface to rivet top
Allowable limit
(Depth)
Pressure Plate Flatness
1. Place a straightedge on the pressure plate and measure
clearance with a feeler gauge at several points.
2. If the clearance exceeds the allowable limit, replace it.
3. When the pressure plate is worn around its outside and its
inside surface only is in contact with the straightedge, replace
even if the clearance is within allowable limit.
Clearance between
pressure plate and Allowable limit
straightedge
A: Inside
Checking Pressure Plate Assembly and Flywheel
1. Wash the disassembling parts except clutch disc with a suitable
cleaning solvent to remove dirt and grease before making
inspection and adjustment.
2. Inspect the friction surface of pressure plate and flywheel for
scoring or roughness.
• Slight roughness may be smoothed by using fine emery
cloth.
• If these parts have deep scores or grooves on their surface,
they should be replaced.
3. Inspect the surface of diaphragm spring for wear.
If excessive wear is found, replace the clutch cover assembly.
4. Inspect thrust rings (wire ring) for wear or damage.
As these parts are invisible from outside, shake pressure plate
assembly up and down to listen for chattering noise, or lightly
hammer on rivets for a slightly cracked noise. Any of these
noises indicates need of replace as a complete assembly.
Diaphragm spring mutual
Allowable limit
difference
2-S31
CLUTCH
2.0 mm
0.079 in.
9Y1211109CLS0007US0
0.3 mm
0.012 in.
9Y1211109CLS0008US0
0.2 mm
0.008 in.
B: Outside
9Y1211109CLS0009US0
0.5 mm
0.020 in.
9Y1211109CLS0010US0
KiSC issued 11, 2014 A