Subaru impreza 2002 Service Manual
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Subaru impreza 2002 Service Manual

Subaru impreza 2002 Service Manual

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2002 IMPREZA SERVICE MANUAL
NEW CAR INFORMATION SECTION
FOREWORD
This manual has been prepared to provide information
for the construction, operation and other technical de-
tails of SUBARU vehicles.
Read this manual thoroughly and make the most of it
to give better service to your customers and improve
your knowledge of vehicle maintenance.
All information, illustration and specifications con-
tained in this manual are based on the latest product
information available at the time of publication ap-
proval.
FUJI HEAVY INDUSTRIES LTD.
QUICK REFERENCE INDEX
Specifications
Fuel Injection (Fuel System)
Emission Control
(Aux. Emission Control Devices)
Intake (Induction)
Mechanical
Control System
Manual Transmission
and Differential
Clutch
Front Suspension
Rear Suspension
Differentials
Drive Shaft System
ABS
Brakes
Instrumentation/Driver Info
SPC
FU (TURBO)
EC (TURBO)
IN (TURBO)
ME (TURBO)
CS
6MT
CL
FS
RS
DI
DS
ABS
BR
IDI
W1841GE

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Summary of Contents for Subaru impreza 2002

  • Page 1 ME (TURBO) This manual has been prepared to provide information for the construction, operation and other technical de- tails of SUBARU vehicles. Control System Read this manual thoroughly and make the most of it to give better service to your customers and improve Manual Transmission your knowledge of vehicle maintenance.
  • Page 2 All right reserved. This book may not be reproduced or copied, in whole or in part, without the written permis- sion of FUJI HEAVY INDUSTRIES LTD., TOKYO JA- SUBARU, are trademarks of FUJI HEAVY INDUSTRIES LTD.  Copyright 2001 FUJI HEAVY INDUSTRIES LTD.
  • Page 3 SPECIFICATIONS Page 1. Impreza ................
  • Page 4 IMPREZA Specifications 1. Impreza A: DIMENSIONS Model Sedan Wagon OUTBACK Overall length mm (in) 4,405 (173.4) Overall width mm (in) 1,730 (68.1) 1,695 (66.7) 1,710 (67.3) 1,730 (68.1) Overall height (at CW) mm (in) 1,465 (57.7), 1,475 (58.1), 1,440 (56.7) 1,440 (56.7) 1,485 (58.5)L4 1,495 (58.9)L4...
  • Page 5 IMPREZA Specifications C: ELECTRICAL Model Non-Turbo 1.6 L Turbo 2.0 L 2.5 L 2.0 L MT: 10° ± Ignition timing at idling speed BTDC/rpm 10°/700 5° ± 10°/700 10° ± 10°/700 12° ± 10°/750 12° ± 10°/700 AT: 15° ± 10°/700 Spark plug Type and...
  • Page 6 IMPREZA Specifications D: TRANSMISSION Model Non-Turbo 1.6 L Turbo 2.0 L 2.5 L 2.0 L Transmission type Clutch type DSPD DSPD DSPD DSPD DSPD Gear ratio 3.454, 3.454 2.785 3.454 2.785 2.785 3.454 2.785 3.636 3.166L1 1.947, 2.062 1.545 2.062 1.545 1.545 2.062...
  • Page 7 IMPREZA Specifications F: SUSPENSION Front Macpherson strut type, Independent, Coil spring Rear Dual-link type, Independent, Coil spring G: BRAKE Model 1.6 L Non-Turbo 2.0 L, 2.5 L Turbo 2.0 L, STi Service brake system Dual circuit hydraulic with vacuum suspended power unit Front Ventilated disc brake Rear...
  • Page 8 IMPREZA Specifications J: WEIGHT 1. LHD VEHICLE Sedan Option codeL1 Model 1.6 L Curb weight (C.W.) Front kgf (lb) (1,609) (1,654) (1,654) (1,698) (1,654) (1,698) (1,631) (1,676) Rear kgf (lb) (1,146) (1,146) (1,146) (1,146) (1,146) (1,146) (1,179) (1,179) Total kgf (lb) 1,250 1,270 1,270...
  • Page 9 IMPREZA Specifications Option codeL1 Model 2.0 L Curb weight (C.W.) Front kgf (lb) (1,643) (1,698) (1,687) (1,742) (1,676) (1,753) (1,653) (1,720) Rear kgf (lb) (1,179) (1,168) (1,168) (1,157) (1,157) (1,168) (1,213) (1,202) Total kgf (lb) 1,280 1,300 1,295 1,315 1,285 1,325 1,300 1,325...
  • Page 10 IMPREZA Specifications Wagon Option codeL1 Model 1.6 L Curb weight (C.W.) Front kgf (lb) (1,620) (1,654) (1,664) (1,698) (1,664) (1,698) (1,642) (1,676) Rear kgf (lb) (1,202) (1,202) (1,202) (1,202) (1,202) (1,202) (1,235) (1,235) Total kgf (lb) 1,280 1,295 1,300 1,315 1,300 1,315 1,305...
  • Page 11 IMPREZA Specifications Option codeL1 Model 2.0 L Curb weight (C.W.) Front kgf (lb) (1,664) (1,698) (1,709) (1,742) (1,720) (1,753) (1,676) (1,720) Rear kgf (lb) (1,257) (1,246) (1,246) (1,235) (1,257) (1,246) (1,279) (1,268) Total kgf (lb) 1,325 1,335 1,340 1,350 1,350 1,360 1,340 1,355...
  • Page 12 IMPREZA Specifications 2. RHD VEHICLE Sedan Option codeL1 Model 1.6 L Curb weight (C.W.) Front kgf (lb) 735 (1,621) 755 (1,665) 750 (1,654) 770 (1,698) Rear kgf (lb) 520 (1,146) 520 (1,146) 520 (1,146) 520 (1,146) Total kgf (lb) 1,255 (2,767) 1,275 (2,811) 1,270 (2,800) 1,290 (2,844)
  • Page 13 IMPREZA Specifications Option codeL1 Model 2.0 L 2.0 L 2.0 L Turbo 2.5 L Turbo Unladen mass (U. M.) Front kgf (lb) (1,654) (1,709) (1,830) (1,885) (1,720) (1,775) (1,973) Rear kgf (lb) (1,179) (1,168) (1,235) (1,224) (1,191) (1,179) (1,268) Total kgf (lb) 1,285 1,305...
  • Page 14 IMPREZA Specifications Wagon Option codeL1 Model 1.6 L Curb weight (C.W.) Front kgf (lb) 740 (1,631) 755 (1,664) 755 (1,664) 770 (1,698) Rear kgf (lb) 545 (1,202) 545 (1,202) 545 (1,202) 545 (1,202) Total kgf (lb) 1,285 (2,833) 1,300 (2,866) 1,300 (2,866) 1,315 (2,900) Maximum permissible...
  • Page 15 IMPREZA Specifications Option codeL1 Model 2.0 L 2.0 L Turbo OUTBACK Unladen mass (U. M.) Front kgf (lb) (1,676) (1,709) (1,653) (1,687) (1,819) (1,874) Rear kgf (lb) (1,257) (1,246) (1,257) (1,257) (1,290) (1,290) Total kgf (lb) 1,330 1,340 1,320 1,335 1,410 1,435 (2,932)
  • Page 16 IMPREZA Specifications MEMO SPC-14...
  • Page 17 FUEL INJECTION (TURBO) (FUEL SYSTEM) Page 1. General 2. Air Line ................3.
  • Page 18 AIR LINE Fuel Injection (Fuel System) 2. Air Line G: TUMBLE GENERATOR VALVES 2. STi MODEL The STi model’s engine is not provided with a tumble generation control function. Although it is fitted with a tumble generator housing, there are no sensor and valve actuator on the housing. FU-2...
  • Page 19 SENSORS AND SWITCHES Fuel Injection (Fuel System) 4. Sensors and Switches D: EXHAUST GAS TEMPERATURE SENSOR 2. STi MODEL The STi model is not provided with an exhaust gas temperature sensor. I: VARIABLE VALVE TIMING CAMSHAFT POSITION SENSORS NOTE: The variable valve timing camshaft position sensors are installed only on the STi model’s engine. The variable valve timing camshaft position sensors are installed one each on the rear ends of the right and left bank cylinder heads.
  • Page 20 CONTROL SYSTEM Fuel Injection (Fuel System) 5. Control System B: INPUT AND OUTPUT SIGNALS Signal Unit Function Pressure sensor Detects the amount of intake air (Measures the absolute pressure). Mass air flow and intake air tempera- Detects the temperature and amount of intake air. ture sensor Throttle position sensor Detects the throttle valve position.
  • Page 21 (TURBO) Page 1. System Overview ..............2.
  • Page 22 SYSTEM OVERVIEW Emission Control (Aux. Emission Control Devices) 1. System Overview There are three emission control systems which are as follows: Crankcase emission control system Exhaust emission control system Three-way catalyst system Air/fuel (A/F) control system Ignition control system Evaporative emission control system NOTE: The STi model is not provided with a precatalytic converter.
  • Page 23 (TURBO) INTAKE (INDUCTION) Page 1. Intake System 2. Turbocharger System ............. . .

  • Page 24: Turbocharger System

    TURBOCHARGER SYSTEM Intake (Induction) 2. Turbocharger System I: INTERCOOLER WATER SPRAY Water is sprayed from the nozzle in the intercooler duct to cool down the intercooler with water spray when the intake air temperature becomes high so that the air temperature is lowered and air intake efficiency is increased.

  • Page 25: Table Of Contents

    (TURBO) MECHANICAL Page 1. General 2. Timing Belt 3. Automatic Belt Tension Adjuster 4. Belt Cover 5. Camshaft ................6.

  • Page 26: Camshaft

    CAMSHAFT Mechanical 5. Camshaft The DOHC engine uses four camshafts in all; intake and exhaust camshafts on each of the right and left banks. The cam lobe noses are finished by “chill” treatment to increase wear resistance and anti-scuffing properties. Each camshaft is supported at its three journals and held in position by three camshaft caps.

  • Page 27: Cylinder Head

    CYLINDER HEAD Mechanical 6. Cylinder Head The cylinder head is made of aluminium die casting. Each combustion chamber in the cylinder head is a compact, pentroof design. The spark plug is located at the center of the combustion chamber, which contributes to creation of a wide “squish area”...

  • Page 28: Cylinder Block

    CYLINDER BLOCK Mechanical 7. Cylinder Block With all the engines except that for the STi model, the cylinder block is made of aluminum die casting. Its open-deck design provides it with such advantageous features as relatively small weight, high rigidity and excellent cooling efficiency. With the engine for the STi model that generates increased torque outputs, the cylinder block uses a semi-closed deck design which can hold the cylinder liners with higher rigidity.

  • Page 29: Piston

    PISTON Mechanical 9. Piston The pistons are of a slipper skirt design for reduced weight and friction. The oil control ring groove utilizes a thermal design. The piston pin is offset either downward (Nos. 1 and 3 pistons) or upward (Nos. 2 and 4 pistons). The piston head has recesses to prevent interference with the intake and exhaust valves.
  • Page 30 VARIABLE VALVE TIMING SYSTEM Mechanical 11. Variable Valve Timing System The STi model’s engine has the variable valve timing system, which adjusts the opening and clos- ing timings of the intake valves optimally by continuously changing the phase angle of the cam- shaft sprocket relative to the camshaft.

  • Page 31: Variable Valve Timing System

    VARIABLE VALVE TIMING SYSTEM Mechanical B: PHASE ANGLE RETARDS In response to a retard signal from the ECM, the oil flow control valve moves its spool such that hydraulic pressure is applied to the retard chamber in the camshaft sprocket. The sprocket is then turned in the direction in which its phase angle retards relative to the camshaft.
  • Page 32 VARIABLE VALVE TIMING SYSTEM Mechanical C: A CERTAIN PHASE ANGLE IS RETAINED When the ECM issues a signal to keep the phase angle unchanged, the oil flow control valve moves its spool to the position at which the hydraulic pressures to/from both the chambers are blocked. The pressures in the chambers are thus maintained, so the phase angle does not change and the intake valves’...
  • Page 33 SODIUM-FILLED EXHAUST VALVES Mechanical 12. Sodium-filled Exhaust Valves The STi model’s engine uses sodium-filled exhaust valves. Each exhaust valve contains pure sodium in its hollow stem. Sodium has high thermal conductivity. The entrapped sodium will liquefy at high temperatures and move inside the stem as the valve is operated.

  • Page 34: Sodium-Filled Exhaust Valves

    SODIUM-FILLED EXHAUST VALVES Mechanical MEMO ME-10...
  • Page 35 CONTROL SYSTEM Page 1. Gear Shift Lever 2. Select Lever 3. Dual Range Selector Lever 4. 6MT Gear Shift lever ..............
  • Page 36 6MT GEAR SHIFT LEVER Control System 4. 6MT Gear Shift Lever A: GENERAL The six-speed manual transmission’s control system has a gear shift lever specially designed for the use with it. The gearshift lever is complete with a parallel-link gear shift mechanism as is the case with the five-speed transmission’s gearshift lever.
  • Page 37 6MT GEAR SHIFT LEVER Control System B: OPERATION When shifting gear into reverse, the driver pulls the slider up (toward the knob). This causes the reverse check cable to move the reverse lever on the six-speed transmission to the lock release position.
  • Page 38 6MT GEAR SHIFT LEVER Control System MEMO CS-4...
  • Page 39 MANUAL TRANSMISSION AND DIFFERENTIAL Page 1. General ................2.
  • Page 40 The oil pump incorporated in the transmission case ensures improved lubricating and cooling performance. An optional SURETRAC type limited slip differential has been introduced for the front differential. The center differential uses a viscous coupling of the type whose high performance has already been proven with the preceding SUBARU models. 6MT-2...

  • Page 41: General

    GENERAL Manual Transmission and Differential NF0598 (1) Main shaft (9) Transfer driven gear (17) 3rd driven gear (2) Reverse idler gear (10) Extesion case (18) 2nd driven gear (3) 1st drive gear (11) Transfer drive gear (19) Oil pan (4) 2nd drive gear (12) Center differential assembly (20) Oil strainer (5) 3rd drive gear...

  • Page 42: Triple-Cone Synchronizer

    TRIPLE-CONE SYNCHRONIZER Manual Transmission and Differential 2. Triple-Cone Synchronizer A: CONSTRUCTION The triple-cone synchronizer has three frictional interfaces - in addition to the two coaxial inter- faces between the synchronizer cone and the inner and outer balk rings (which are same as those with a double-cone synchronizer), it has a third frictional interface between the inner surface of the inner balk ring and the cone on the 2nd driven gear.

  • Page 43: Reverse Idler Gear Assembly (With Synchronizing Mechanism)

    REVERSE IDLER GEAR ASSEMBLY (WITH SYNCHRONIZING MECHANISM) Manual Transmission and Differential 3. Reverse Idler Gear Assembly (with Synchronizing Mechanism) A constant-mesh type reverse gearing is used in the six-speed manual transmission. The reverse idler gear assembly is provided with a double-cone synchronizer. Soon after disengagement of the clutch, the reverse gear remains rotating by an inertial force.
  • Page 44 REVERSE IDLER GEAR ASSEMBLY (WITH SYNCHRONIZING MECHANISM) Manual Transmission and Differential To prevent rattling noise that may occur with the constant-mesh type reverse gearing, No.1 re- verse idler gear is fitted with a subgear that has the same number of teeth as the No. 1 reverse idler gear.

  • Page 45: Shift And Select Mechanism

    SHIFT AND SELECT MECHANISM Manual Transmission and Differential 4. Shift and Select Mechanism Each of the shifter and fork rods has a detent mechanism using a plunger with a ball in it and is supported with a slidable ball bearing. The detent mechanisms give the driver distinctive detent feeling and the slidable ball bearings help reduce the shift lever operating force.
  • Page 46 SHIFT AND SELECT MECHANISM Manual Transmission and Differential A: MECHANISMS 1. SHIFT DETENT MECHANISM The shift detent mechanism allows the driver to distinctively feel the shift into a gear. The mecha- nism also prevents the transmission from jumping out of gear. The shift detent mechanism uses a plunger with a check ball in it.
  • Page 47 SHIFT AND SELECT MECHANISM Manual Transmission and Differential 2. SELECT RETURN MECHANISM The select return mechanism allows the shift lever to return to the neutral position. The neutral set spring pinches between its two arms the four pins on the No. 1 selector arm to hold the shift lever always in the neutral position.
  • Page 48 SHIFT AND SELECT MECHANISM Manual Transmission and Differential 3. INTERLOCK MECHANISM (DOUBLE-MESHING PREVENTION MECHANISM) The interlock mechanism makes it impossible to shift the transmission into two gears at once. When the interlock arm selects the shifter arm corresponding to the gear into which the driver is going to make a shift, the interlock blocks also move in the same select direction, preventing the other shifter arms from being selected.
  • Page 49 SHIFT AND SELECT MECHANISM Manual Transmission and Differential When “double meshing” is prevented NF0606 [A] Preventing 3rd and 5th double meshing [B] Preventing 6th and reverse double meshing (1) Interlock arm (5) 1st-2nd shifter arm (2) Interlock block (6) Reverse interlock block (3) 5th-6th shifter arm (7) Reverse shifter arm (4) 3rd-4th shifter arm...

  • Page 50: Reverse Check Mechanism

    REVERSE CHECK MECHANISM Manual Transmission and Differential 5. Reverse Check Mechanism The reverse check mechanism prevent the reverse gear from being accidentally engaged when the driver makes a shift into the 5th or 6th gear. This mechanism is provided with a fail-safe function which enable shifting into reverse if the reverse check cable should be broken.
  • Page 51 REVERSE CHECK MECHANISM Manual Transmission and Differential B: OPERATION 1. MAKING SHIFT INTO 5TH/6TH When the shift lever is moved into the 5th or 6th position, the No. 1 selector arm comes into contact with the reverse check plunger, trying to move the reverse check plug. However, one end of the plunger is in contact with the cam lobe on the reverse check shaft and the other end is held in the groove in the reverse check plug, so the selector arm cannot move in the reverse gear selecting direction.
  • Page 52 REVERSE CHECK MECHANISM Manual Transmission and Differential 2. MAKING SHIFT INTO REVERSE When making a shift into reverse, the driver lifts the slider on the shift lever. The upward movement of the slider causes, via the reverse check cable, the reverse check shaft to turn such that the cam lobe on the reverse check shaft becomes clear of the plunger.
  • Page 53 REVERSE CHECK MECHANISM Manual Transmission and Differential 3. FAIL-SAFE OPERATION Should the reverse check cable be broken, the reverse check shaft turns counterclockwise by a spring force, making the plunger get clear of the cam lobe of the reverse check shaft. The plunger can now move toward the reverse check shaft, allowing the selector arm to turn in the reverse selecting direction.

  • Page 54: Center Differential

    CENTER DIFFERENTIAL Manual Transmission and Differential 6. Center Differential A: CONSTRUCTION The center differential consists of a set of bevel gears and a viscous coupling. The center differential has the following two functions: distributing the engine torque to the front and rear wheel drive shafts and absorbing the difference in rotating speed between the front and rear wheels.
  • Page 55 CENTER DIFFERENTIAL Manual Transmission and Differential B: MECHANISM OF VISCOUS COUPLING The viscous coupling consists of a number of alternately arranged inner and outer plates and air- and-silicone oil mixture filled into a sealed space that is formed by the center differential case and the rear side gear of the differential gear set.
  • Page 56 CENTER DIFFERENTIAL Manual Transmission and Differential 1. TORQUE CHARACTERISTICS When a speed difference occurs between the center differential case and the rear side gear, a shear force is generated in the silicone oil placed between the outer and inner plates. The torque is then transmitted by the silicone oil between the center differential case and the rear side gear.
  • Page 57 CENTER DIFFERENTIAL Manual Transmission and Differential C: FUNCTION When there is no speed difference between the front and rear wheels, the center differential deliv- ers the engine torque to the front and rear wheels at a ratio of 50:50. When a rotating speed difference occurs between the front and rear wheels, the center differential operates to absorb it in a controlled way by the function of the viscous coupling.
  • Page 58 CENTER DIFFERENTIAL Manual Transmission and Differential 2. DURING TURNS AT LOW SPEEDS During turns at low speeds, rotating speed difference occurs between the front and rear wheels, as well as between the left and right wheels. More particularly, the front wheels rotate faster than the rear wheels.
  • Page 59 CENTER DIFFERENTIAL Manual Transmission and Differential 3. DRIVING ON ROUGH OR SLIPPERY ROADS When front wheels are on a slippery surface When the front wheels begin to spin, the resulting speed difference between the front and rear drive shafts causes the viscous coupling to generate significant amount of shear torque. As a re- sult, the torque distributed to the rear wheels becomes much larger than that distributed to the spinning front wheels.

  • Page 60: Oil Pump

    OIL PUMP Manual Transmission and Differential 7. Oil Pump A: CONSTRUCTION The lubricating oil pump incorporated in the transmission case is of a trochoid type. The pump consists of an inner rotor having four teeth, outer rotor having five teeth, oil pump cover and oil pump driven gear, which are all located at the rear of the transmission case.

  • Page 61: Lubrication System

    LUBRICATION SYSTEM Manual Transmission and Differential 8. Lubrication System A forced lubrication system using an oil pump has been employed to ensure adequate supply of oil to the components of the six-speed transmission. The oil (gear oil) from the oil pump is distributed to the oil chamber, main shaft, drive pinion shaft, transfer gears, and other components.
  • Page 62 FRONT DIFFERENTIAL (SURETRAC TYPE LIMITED SLIP DIFFERENTIAL) Manual Transmission and Differential 9. Front Differential (SURETRAC Type Limited Slip Differential) A: OUTLINE The limited slip differential (LSD) automatically limits the differential action and distributes torque to the left and right wheels adequately to enhance driving stability when the left and right wheels are rotating at speeds different from each other during driving on a slippery road (muddy, snow- covered or slushy road) or cornering.

  • Page 63: Front Differential (Suretrac Type Limited Slip Differential)

    FRONT DIFFERENTIAL (SURETRAC TYPE LIMITED SLIP DIFFERENTIAL) Manual Transmission and Differential NF0578 (1) Cage (2) Cam follower (3) Face cam 6MT-25...
  • Page 64 FRONT DIFFERENTIAL (SURETRAC TYPE LIMITED SLIP DIFFERENTIAL) Manual Transmission and Differential C: OPERATION 1. WHEN RIGHT AND LEFT WHEELS ROTATE AT DIFFERENT SPEEDS If the left and right wheels move relative to each other in the direction of arrow Z and in the direction of arrow Y, respectively, the cam follower A is pushed by the slope B of the left face cam, moving to the right.
  • Page 65 FRONT DIFFERENTIAL (SURETRAC TYPE LIMITED SLIP DIFFERENTIAL) Manual Transmission and Differential 2. WHEN RIGHT AND LEFT WHEELS ROTATE AT THE SAME SPEED During normal straight-ahead driving where the right and left wheels rotate at the same speed, the cage and cam followers rotate together, just as in conventional differentials. As a result, driving torque is distributed equally to the right and left side gears.
  • Page 66 FRONT DIFFERENTIAL (SURETRAC TYPE LIMITED SLIP DIFFERENTIAL) Manual Transmission and Differential 3. WHEN TRACTION IS DIFFERENT BETWEEN RIGHT AND LEFT WHEELS For example, if the left wheel spins on a slippery surface and loses traction, the left face cam starts rotating at a speed faster than the right wheel.
  • Page 67 TRANSMISSION MOUNTING Manual Transmission and Differential 10. Transmission Mounting NF0628 (1) Pitching stopper (2) Cushion rubber (3) Cross member (4) Dynamic damper (Europe model) 6MT-29...

  • Page 68: Transmission Mounting

    TRANSMISSION MOUNTING Manual Transmission and Differential MEMO 6MT-30...
  • Page 69 CLUTCH Page 1. Outline 2. Operation 3. Cross Sectional View ..............4.
  • Page 70 CROSS SECTIONAL VIEW Clutch 3. Cross Sectional View E: STi MODEL NF0621 (1) Spring bracket (5) Flywheel (9) Ball bearing (2) Spring (6) Clutch cover (10) Release bearing (3) Release lever (7) Clutch disc (4) Operating cylinder (8) Transmission main shaft CL-2...
  • Page 71 FLUID CONTROL SYSTEM (STi MODEL) Clutch 7. Fluid Control System (STi Model) The clutch operating cylinder incorporates a temperature sensitive orifice unit which controls the clutch engaging speed depending on the fluid temperature to ensure smooth standing starts irre- spective of atmospheric temperatures. A: CONSTRUCTION The orifice unit consists of an orifice retainer, an orifice valve, and two springs that support the ori- fice valve.
  • Page 72 FLUID CONTROL SYSTEM (STi MODEL) Clutch B: OPERATION The No. 1 spring is made of a shape memory alloy that contracts and loses the tension when the temperature is low. When the temperature is high, the orifice valve is kept in a raised position by the No. 1 spring, so the fluid passage is narrow.
  • Page 73 FRONT SUSPENSION Page 1. Front Suspension ..............

  • Page 74: Front Suspension

    FRONT SUSPENSION Front Suspension 1. Front Suspension A: OUTLINE 1. STi MODEL The struts are of an upside-down type, which can provide increased rigidity. They also improve the steering stability. FS-2...
  • Page 75 FRONT SUSPENSION Front Suspension B: CONSTRUCTION 3. UPSIDE-DOWN-TYPE STRUTS (STi MODEL) Compared with a conventional suspension strut, the upside-down-type strut has a shock absorber with its top and bottom reversed. This arrangement is advantageous in increasing rigidity as it al- lows the diameter of the damping tube (which corresponds to the piston rod in the conventional arrangement) to be increased to an almost same diameter as the strut’s outer tube diameter.
  • Page 76 FRONT SUSPENSION Front Suspension MEMO FS-4...
  • Page 77 REAR SUSPENSION Page 1. Rear Suspension ..............

  • Page 78: Rear Suspension

    REAR SUSPENSION Rear Suspension 1. Rear Suspension A: OUTLINE 1. STi MODEL As is the case with the front suspension, the rear suspension uses upside-down struts. RS-2...
  • Page 79 DIFFERENTIALS Page 1. Rear Differential ..............2.
  • Page 80 REAR DIFFERENTIAL Differentials 1. Rear Differential B: T-TYPE 2. STi MODEL The drive gear is a hypoid gear with a nominal diameter of 180 mm (7.09 in). The drive pinion shaft is supported by three bearings. The bearing preload is adjusted by selecting a spacer and washer combination of a proper thickness.
  • Page 81 DRIVE SHAFT SYSTEM Page 1. Propeller Shaft ............... 2.
  • Page 82 PROPELLER SHAFT Drive Shaft System 1. Propeller Shaft C: STi MODEL The propeller shaft is of a two-piece design that uses three joints. NF0558 (1) Center bearing (A) Transmission side (B) Rear differential side DS-2...
  • Page 83 FRONT AXLE Drive Shaft System 2. Front Axle A: GENERAL 2. STi MODEL The inboard end of the axle shaft is connected to the transmission via a constant velocity joint (double offset joint: DOJ) which is flexible in the axial directions, while the outboard end is con- nected via a bell joint (BJ) to the wheel hub which is supported by a taper roller bearing located inside the axle housing.
  • Page 84 FRONT AXLE Drive Shaft System B: FRONT DRIVE SHAFT 2. STi MODEL A double offset joint (DOJ) is used on the differential side of each front drive shaft. The DOJ can be disassembled for maintenance. It provides a maximum operating angle of 25° and can be moved in the axial directions.
  • Page 85 REAR AXLE Drive Shaft System 3. Rear Axle C: AWD TURBO MODELS 2. STi MODEL The inboard end of each axle shaft is connected to the transmission via a double offset joint (DOJ) which can extend and retract in the axial directions. The outboard end is supported by taper roller bearings located inside the axle housing via a bell joint (BJ) which features a large operating angle.
  • Page 86 REAR AXLE Drive Shaft System D: REAR DRIVE SHAFT 3. TURBO MODELS (STi MODEL) A double offset joint (DOJ) is used on the differential side of each rear drive shaft. The DOJ can be disassembled for maintenance. It provides a maximum operating angle of 23° and can be moved in the axial directions.
  • Page 87 Page 1. Anti-lock Brake System (ABS) ........... . .
  • Page 88 ANTI-LOCK BRAKE SYSTEM (ABS) 1. Anti-lock Brake System (ABS) A: FEATURE The 5.3i type ABS used in the Impreza has a hydraulic control unit, an ABS control module, a valve relay and a motor relay integrated into a single unit (called “ABSCM & H/U”) for circuit sim- plicity and reduced weight.
  • Page 89 (ABSCM & H/U) (2) Diagnosis connector (6) G sensor (10) ABS sensor (3) Data link connector (7) Lateral G sensor (Only STi model) (11) Brake switch (for SUBARU select monitor) (4) ABS warning light (8) Tone wheel (12) Master cylinder ABS-3...
  • Page 90 D Whenever the ignition switch is placed at ON, the module performs a self diagnosis sequence. If anything wrong is detected, the module cuts off the system. D It communicates with the SUBARU select monitor. D When the ABS is active, the H/U changes fluid passages to the wheel cylin- H/U section ders in response to commands from the ABSCM.
  • Page 91 ANTI-LOCK BRAKE SYSTEM (ABS) NF0587 (1) ABS control module and hydraulic (11) Rear left outlet solenoid valve (21) Lateral G sensor (Only STi model) control unit (2) ABS control module section (12) Rear right inlet solenoid valve (22) Front left ABS sensor (3) Valve relay (13) Rear right outlet solenoid valve (23) Front right ABS sensor...
  • Page 92 ANTI-LOCK BRAKE SYSTEM (ABS) J: LATERAL G SENSOR (STi MODEL) The lateral G sensor senses variation in the lateral acceleration while the vehicle is making a turn. Its construction and operation are the same as those of the conventional G sensor, which converts changes in the piezoresistivity into changes in the output voltage to the ABSCM.
  • Page 93 BRAKES Page 1. Front and Rear Disc Brakes ............2.
  • Page 94 FRONT AND REAR DISC BRAKES Brakes 1. Front and Rear Disc Brakes C: STi MODEL The brakes of the STi model use Brembo’s 17-inch calipers and ventilated disc rotors that pro- vide improved braking performance. The brake calipers for the front brakes are of a four-pod-piston type, while those for the rear brakes are of a two-pod-piston type.
  • Page 95 INSTRUMENTATION/DRIVER INFO Page 1. Combination Meter ..............2.
  • Page 96 COMBINATION METER Instrumentation/Driver Info 1. Combination Meter A: WARNING AND INDICATOR LIGHTS 2. STi MODEL NF0592 (1) CHECK ENGINE warning light This light illuminates when a fault occurs in the MFI (Multiple point Fuel Injection) system. (2) Brake fluid level warning / parking brake indicator light This light illuminates when the fluid level in the brake reservoir tank lowers below the specified level and/or when the parking brake is applied.
  • Page 97 COMBINATION METER Instrumentation/Driver Info If everything is normal, the warning and indicator lights should be ON or OFF as shown below ac- cording to ignition switch positions. Warning/Indicator light Ignition switch position LOCK/ACC While engine is running (1) CHECK ENGINE (2) Brake fluid level / parking brake (3) AIRBAG (4) ABS...
  • Page 98 COMBINATION METER Instrumentation/Driver Info B: TELLTALE (GRAPHIC MONITOR) 2. STi MODEL NF0593 (1) Turn signal indicator light This light blinks in unison with the corresponding turn signal lights when the turn signal switch is operated. (2) REV indicator light This light illuminates when a preset engine speed is exceeded. (3) Seat belt warning light This light stays illuminated for about 6 seconds after the ignition switch has been turned ON if the driver’s seat belt is not fastened.
  • Page 99 COMBINATION METER Instrumentation/Driver Info If everything is normal, the telltales should be ON, OFF or in other states as shown below according to ignition switch positions. Telltale light Ignition switch position LOCK/ACC While engine is running (1) Turn signal Blink Blink Blink (2) REV...
  • Page 100 COMBINATION METER Instrumentation/Driver Info E: TACHOMETER 2. REV INDICATOR LIGHT The REV indicator light operates together with a buzzer when the engine starts operating at a speed exceeding the speed the driver has set as desired, giving him or her a warning. The light remains illuminated as long as the engine speed is above the set speed.

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