Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 465

CL-35

Clutch Switch

CLUTCH SYSTEM

(3) Check that the switch is turned on and off in

Dimension L.

Dimension L:

5 — 6.5 mm (0.2 — 0.26 in)

D: ADJUSTMENT

1) Loosen the lock nut of clutch start switch.

2) Fully depress the clutch pedal and hold it.

3) Adjust the gap of the clutch pedal plate and the

clutch switch to be 1.1 — 2.1 mm (0.04 — 0.08 in).

4) Tighten the lock nut.
Tightening torque:

8 N·m (0.8 kgf-m, 5.9 ft-lb)

(A) ON
(B) OFF

(A) Lock nut
(B) Clutch start switch

(A) Plate
(B) Clutch start switch

(C) 1.1 — 2.1 mm (0.04 — 0.08 in)

CL-00799

L

(B)

(A)

(A)

(B)

CL-00105

(A)

(B)

(C)

CL-00104

CL-36

General Diagnostic Table

CLUTCH SYSTEM

12.General Diagnostic Table

A: INSPECTION

1. CLUTCH

Symptoms

Possible cause

Corrective action

1. Clutch slippage.
It is hard to perceive clutch slippage in
the early stage, but pay attention to the
following symptoms.
• Engine speeds up when shifting.
• High-speed driving is not possible;
especially rapid acceleration is not possi-
ble and vehicle speed does not increase
in proportion to the increase in engine
speed.
• Power drops particularly when ascend-
ing a slope, and there is a burning smell
of the clutch plate.
• Method of testing: Park the vehicle and
fully apply the parking brake. Disengage
the clutch and shift the transmission gear
into the 1st. Gradually increase the
engine speed while gradually allowing the
clutch to engage. The clutch function is
satisfactory if the engine stalls. However,
the clutch is slipping if the vehicle does
not move forward and the engine does
not stall.

(a) Oil on the clutch face

Replace.

(b) Worn clutch face

Replace.

(c) Deteriorated diaphragm spring

Replace.

(d) Warped pressure plate or flywheel

Repair or replace.

(e) Defective release bearing holder

Repair or replace.

2. Clutch drags.
As a symptom of this trouble, a harsh
scratching noise occurs and control
becomes difficult when shifting gears.
The symptom becomes more apparent
when shifting into the 1st gear. However,
because most trouble of this sort is due to
a defective synchronization mechanism,
perform the following tests.
• Method of testing: <Ref. to CL-37,
DIAGNOSTIC DIAGRAM OF CLUTCH
DRAG, INSPECTION, General Diagnos-
tic Table.>
The problem is caused by insufficient dis-
engagement of the clutch if an abnormal
noise occurs during this test.

(a) Worn or rusty clutch disc hub spline

Replace the clutch disc.

(b) Excessive deflection of clutch disc
face

Repair or replace.

(c) Crankshaft pilot needle bearing stick-
ing

Replace.

(d) Cracked clutch disc face

Replace.

(e) Stuck clutch disc (smeared by oil or
water)

Replace.

3. Clutch chatters.
Clutch chattering is an unpleasant vibra-
tion to the whole vehicle when the vehicle
is just started with clutch partially
engaged.

(a) Adhesion of oil on the clutch face

Replace the clutch disc.

(b) Weak or broken damper spring

Replace the clutch disc.

(c) Poor contact of the disc surface or
excessively worn disc

Replace the faulty clutch disc.

(d) Warped pressure plate or flywheel

Repair or replace.

(e) Loose disc rivets

Replace the clutch disc.

(f) Loose engine mounting

Retighten or replace mounting.

(g) Loose pitching stopper

Retighten or replace the pitching stopper.

CL-37

General Diagnostic Table

CLUTCH SYSTEM

2. CLUTCH PEDAL

3. DIAGNOSTIC DIAGRAM OF CLUTCH DRAG

4. Noisy clutch
Examine whether the noise is generated
when the clutch is disengaged, engaged,
or partially engaged.

(a) Broken, worn or insufficiently lubri-
cated release bearing

Replace the release bearing.

(b) Insufficient lubrication of the pilot
bearing

Replace the pilot bearing.

(c) Loose clutch disc hub

Replace the clutch disc.

(d) Loose damper spring retainer

Replace the clutch disc.

(e) Deteriorated or broken damper spring Replace the clutch disc.

5. Clutch grabs suddenly.
When starting the vehicle with the clutch
partially engaged, the clutch engages
suddenly and the vehicle jumps instead
of making a smooth start.

(a) Grease or oil on facing

Replace the clutch disc.

(b) Deteriorated cushioning spring

Replace the clutch disc.

(c) Worn or rusted spline of clutch disc or
main shaft

Take off rust, apply grease or replace
clutch disc or main shaft.

(d) Deteriorated or broken damper spring Replace the clutch disc.
(e) Loose engine mounting

Retighten or replace mounting.

(f) Deteriorated diaphragm spring

Replace.

Symptoms

Corrective action

Insufficient pedal play

Adjust the free play of the pedal.

Insufficient clutch pedal free play

Adjust the free play of the pedal.

Excessively worn and damaged pedal shaft and/or bushing

Replace the bushing or shaft with a new part.

Step

Check

Yes

No

1

CHECK GEAR NOISE.
1) Start the engine.
2) While idling the engine, step on the clutch
pedal and quickly shift from neutral to reverse.

Is there any abnormal noise
from the transmission gear?

Go to step

2.

Clutch is normal.

2

CHECK GEAR NOISE.
Depress the clutch pedal at idle and shift from
neutral to reverse within 0.5 — 1.0 second.

Is there any abnormal noise
from the transmission gear?

Go to step

3.

Defective trans-
mission or exces-
sive clutch drag
torque. Inspect
pilot bearing,
clutch disc, trans-
mission and clutch
disc hub spline.

3

CHECK GEAR NOISE.
1) Depress the clutch pedal at idle and shift
from neutral to reverse within 0.5 — 1.0 second.
2) While stepping on the clutch pedal, shift
from neutral to reverse, reverse to neutral sev-
eral times.

Is there any abnormal noise
from the transmission gear?

Inadequate clutch
disengage. Inspect
the clutch disc,
clutch cover, clutch
release, and clutch
pedal free play.

Clutch and fly-
wheel seizure.
Inspect the clutch
disc and the spline
of the clutch disc
hub.

Symptoms

Possible cause

Corrective action

CL-38

General Diagnostic Table

CLUTCH SYSTEM