User Guide
EXEDY Globalparts Corporation • 800.346.6091 • www.exedyusa.com
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EXEDY Globalparts Corporation • 800.346.6091 • www.exedyusa.com
30
Malfunctions of Clutch Discs
Malfunctions of Clutch Discs
PROBLEM:
Dierent number of spline on main drive to
those on clutch disc/diameter of spline incorrect.
SYMPTOM:
Unable to t clutch disc on main drive shaft.
CAUSE:
Careless tting practice. The right clutch disc
was not checked on main drive spline before
installation.
SOLUTION:
1. Always refer to EXEDY/Daikin packaging
instructions before installing clutch.
2. Try clutch disc on main drive for smooth sliding
before installation.
PROBLEM:
Noisy and cannot transfer power/splines
completely disintegrated.
SYMPTOM:
No drive.
CAUSE:
1. Clutch disc not tested on spline before
installation.
2. Missing spigot/pilot bearing or bushing.
SOLUTION:
1. Always check clutch disc for smooth sliding on
spline.
2. Check and replace spigot/pilot bearing of
bushing. (Mini UK and Europe: Check primary
gear for worn bushing; if worn replace).
PROBLEM:
Crashing in all gears/damaged and
burred splines.
SYMPTOM:
Dicult to disengage gears.
CAUSE:
Defective pilot bearing or bush. This causes
angular wear on the spline teeth, not allowing
the clutch disc to slide on the spline teeth. It also
causes the clutch disc to possibly stick on to the
ywheel or not separate from the clutch cover
pressure plate assembly. This results in poor
separation, no disengagement.
SOLUTION:
Fit new pilot bearing or bush.
PROBLEM:
Burst clutch disc/no transmitted power.
SYMPTOM:
Clutch slip.
CAUSE:
1. The clutch was engaged while coasting
downhill causing the facings to burst through
extreme shock.
2. Gear being shifted down when the vehicle engine is revving
lower than the transmission ratios, resulting in excessive RPM
at the driveline end. This is beyond the capacity of the burst
strength specications of the friction material.
3. Lock of free travel caused by faulty clutch slave cylinder
or air over hydraulic system (common in Japanese truck
applications). With a new clutch kit installed keeping in mind
the diaphragm tips/release lever tips are further down due to
the thickness of the new clutch disc. The slave cylinder piston
will now be operating further towards the end of the cylinder
where it has not worked for some time, depending on
adjustment and travel. This area in the cylinder may possibly
be corroded, again keeping in mind that brake uid is a
hygroscopic liquid, which is very absorbent of moisture and
moisture corrodes and could result in the piston jamming
and not returning, therefore, causing the release mechanism
to activate the clutch in a semi disengaged position.
The above corrosion problem would also apply to the air
canister in the air over hydraulic assist system. A partly
disengaged clutch generates extreme heat aecting the
clamp load of the diaphragm spring/coil spring ultimately
causing the friction material to burst. This is always indicated
by the blue and burnt coloring on the pressure plate cover
assembly casting and clutch disc. A strong burnt smell is also
noticeable.
4. Driver resting foot on clutch.
5. Lack of free travel and proper adjustment.
6. Wrong dierential speed selected to match with chosen
gear (trucks with 2 speed dierentials.)
SOLUTION:
1. Driver education for 1, 2, 4, and 6.
2. Check clutch release mechanism, air system
and hydraulics for 3.
3. Adjust clutch to manufacturer’s specications
for 5.
PROBLEM:
Damaged facing material.
CAUSE:
1. Clutch disc has been dropped possibly during
installation or;
2. Damaged in transit.
SOLUTION:
Always check before installation that
facing is intact. Replace clutch disc.