2004 SUBARU IMPREZA WRX Owners Manual

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Maintenance and service
Brake booster
If the brake booster does not operate as described be-
low, have it checked by your SUBARU dealer.
1. With the engine off, depress the brake pedal sever-
al times, applying the same pedal force each time. The
distance the pedal travels should not vary.
2. With the brake pedal depressed, start the engine.
The pedal should move slightly down to the floor.
3. With the brake pedal depressed, stop the engine
and keep the pedal depressed for 30 seconds. The
pedal height should not change.
4. Start the engine again and run for about one minute
then turn it off. Depress the brake pedal several times
to check the brake booster. Brake booster operates
properly if the pedal stroke decreases with each de- pression.Brake pedal
Check the brake pedal free play and reserve distance
according to the maintenance schedule in the “War-
ranty and Maintenance Booklet”. !
Checking the brake pedal free play
1) 0.04 – 0.12 in (1.0 – 3.0 mm)
Stop the engine and firmly depress the brake pedal
several times. Lightly press the brake pedal down with
one finger to check the free play with a force of less
than 2 lb (10 N, 1 kg).
If the free play is not within proper specification, con-
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Maintenance and service
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tact your SUBARU dealer. !Checking the brake pedal reserve dis- tance
1) More than 2.56 in (65 mm)
Depress the pedal with a force of approximately 66 lb
(294 N, 30 kg) and measure the distance between the
upper surface of the pedal pad and the floor.
When the measurement is smaller than the specifica-
tion, or when the pedal does not operate smoothly,
contact with your SUBARU dealer.Clutch pedal (MT vehicles)
Check the clutch pedal free play and reserve distance
according to the maintenance schedule in the “War-
ranty and Maintenance Booklet”. ! Checking the clutch function
Check the clutch engagement and disengagement.
1. With the engine idling, check that there are no ab-
normal noises when the clutch pedal is depressed,
and that shifting into 1st or reverse feels smooth.
2. Start the vehicle by releasing the pedal slowly to
check that the engine and transmission smoothly cou-
ple without any sign of slippage.
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Maintenance and service
!
Checking the clutch pedal free play
1) 0.16 – 0.51 in (4.0 –13.0 mm)
Lightly press the clutch pedal down with your finger
until you feel resistance, and check the free play.
If the free play is not within proper specification, con-
tact your SUBARU dealer.Replacement of brake pad and lining
The front disc brakes and the right rear disc brake
have an audible wear indicators on the brake pads. If
the brake pads wear close to their service limit, the
wear indicator makes a very audible scraping noise
when the brake pedal is applied.
If you hear this scraping noise each time you apply the
brake pedal, have the brake pads serviced by your
SUBARU dealer as soon as possible.
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Maintenance and service
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If you continue to drive despite the scraping
noise from the audible brake pad wear indica-
tor, it will result in the need for costly brake ro-
tor repair or replacement.
! Breaking-in of new brake pads and lin- ings
When replacing the brake pad or lining, use only gen-
uine SUBARU parts. After replacement, the new parts
must be broken in as follows: ! Brake pad and lining
While maintaining a speed of 30 to 40 mph (50 to 65
km/h), step on the brake pedal lightly. Repeat this five
or more times. ! Parking brake lining
1. Drive the vehicle at a speed of about 22 mph (35 km/h).
2. With the parking brake release button pushed in,
pull the parking brake lever SLOWLY and GENTLY.
(Pulling with a force of approximately 33 lb [147 N, 15 kg].)
3. Drive the vehicle for about 220 yards (200 meters) in this condition.
4. Wait 5 to 10 minutes for the parking brake to cool
down. Repeat this procedure.
5. Check the parking brake stroke. If the parking
brake stroke is out of the specified range, adjust it by
turning the adjusting nut located on the parking brake
lever.
Parking brake stroke:
7 – 8 notches / 44 lb (196 N, 20 kg)
A safe location and situation should be select-ed for break-in driving.
Pulling the parking brake lever too forcefully
may cause the rear wheels to lock. To avoid
this, be certain to pull the lever up slowly and
gently.

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Maintenance and service
Parking brake stroke
Check the parking brake stroke according to the main-
tenance schedule in the “Warranty and Maintenance
Booklet”. When the parking brake is properly adjusted,
braking power is fully applied by pulling the lever up
seven to eight notches gently but firmly (about 44 lb,
196 N, 20 kg). If the parking brake lever stroke is not
within the specified range, have the brake system
checked and adjusted at your SUBARU dealer.Tires and wheels !
Types of tires
You should be familiar with type of tires present on your vehicle.
The factory-fitted 17-inch tires on the WRX-STi are
summer tires. The factory-fitted tires on other versions
are all-season tires. The 17-inch tires that can be deal-
er-fitted on the WRX as an option are summer tires. ! All season tires
All season tires are designed to provide an adequate
measure of traction, handling and braking perfor-
mance in year-round driving including snowy and icy
road conditions. However all season tires do not offer
as much traction performance as winter (snow) tires in
heavy or loose snow or on icy roads.
All season tires are identified by “ALL SEASON” and/
or “M+S” (Mud & Snow) on the tire sidewall. ! Summer tires
Summer tires are high-speed capability tires best suit-
ed for highway driving under dry conditions.
Summer tires are inadequate for driving on slippery
roads such as on snow-covered or icy roads.
If you drive your vehicle on snow-covered or icy roads,
we strongly recommend the use of winter (snow) tires.
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Maintenance and service
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When installing winter tires, be sure to replace all four
tires. !Winter (snow) tires
Winter tires are best suited for driving on snow-cov-
ered and icy roads. However winter tires do not per-
form as well as summer tires and all season tires on
roads other than snow-covered and icy roads. ! Tire inspection
Check on a daily basis that the tires are free from se-
rious damage, nails, and stones. At the same time,
check the tires for abnormal wear.
Contact your SUBARU dealer immediately if you find
any problem.
NOTE " When the wheels and tires strike curbs or are
subjected to harsh treatment as when the vehicle
is driven on a rough surface, they can suffer dam-
age that cannot be seen with the naked eye. This
type of damage does not become evident until
time has passed. Try not to drive over curbs, pot-
holes or on other rough surfaces. If doing so is un-
avoidable, keep the vehicle’s speed down to a
walking pace or less, and approach the curbs as
squarely as possible. Also, make sure the tires are not pressed against the curb when you park the vehicle. "
If you feel unusual vibration while driving or find
it difficult to steer the vehicle in a straight line, one
of the tires and/or wheels may be damaged. Drive
slowly to the nearest authorized SUBARU dealer
and have the vehicle inspected. ! Tire pressures and wear
Maintaining the correct tire pressures helps to maxi-
mize the tires’ service lives and is essential for good
running performance. Check and, if necessary, adjust
the pressure of each tire (including the spare) at least
once a month (for example, during a fuel stop) and be-
fore any long journey.

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Maintenance and service
Check the tire pressures when the tires are cold. Use
a pressure gauge to adjust the tire pressures to the
values shown on the tire placard. The tire placard is lo-
cated on the door pillar on the driver’s side.
Driving even a short distance warms up the tires and
increases the tire pressures. Also, the tire pressures
are affected by the ambient temperature. It is best to
check tire pressure outdoors before driving the vehi-cle.
When a tire becomes warm, the air inside it expands,
causing the tire pressure to increase. Be careful not to
mistakenly release air from a warm tire to reduce its
pressure.
NOTE "
The air pressure in a tire increases by approxi-
mately 4.3 psi (30 kPa, 0.3 kg/cm 2
) when the tire
becomes warm. " The tires are considered cold when the vehicle
has been parked for at least three hours or has
been driven less than one mile (1.6 km).
Do not let air out of warm tires to adjust press-
rue. Doing so will result in low tire pressure.
Incorrect tire pressures detract from controllability and
ride comfort, and they cause the tires to wear abnor- mally.UGB510BA

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Maintenance and service
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"Correct tire pressure (tread worn evenly)
Roadholding is good, and steering is responsive. Roll-
ing resistance is low, so fuel consumption is also low- er. "
Abnormally low tire pressure (tread worn at
shoulders)
Rolling resistance is high, so fuel consumption is also
higher.
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