wheel alignment NISSAN ALMERA N16 2003 Electronic Repair Manual

NJMA0036
Shown below are Pre-delivery Inspection Items required for the new vehicle. It is recommended that
necessary items other than those listed here be added, paying due regard tothe conditions in each
country.
Perform applicable items on each model. Consult text of this section for specifications.
UNDER HOOD — engine off
Radiator coolant level and coolant hose connections for leaks
Battery fluid level, specific gravity and conditions of battery terminals
Drive belts tension
Fuel filter for water or dusts (Diesel only), and fuel lines and connections for leaks
Engine oil level and oil leaks
Clutch and brake reservoir fluid level and fluid lines for leaks
Windshield and rear window washer and headlamp cleaner reservoir fluid level
Power steering reservoir fluid level and hose connections for leaks
ON INSIDE AND OUTSIDE
Remove front spring/strut spacer (If applicable)
Operation of all instruments, gauges, lights and accessories
Operation of horn(s), wiper and washer
Steering lock for operation
Check air conditioner for gas leaks
Front and rear seats, and seat belts for operation
All moldings, trims and fittings for fit and alignment
All windows for operation and alignment
Hood, trunk lid, door panels for fit and alignment
Latches, keys and locks for operation
Weatherstrips for adhesion and fit
Headlamp aiming
Tighten wheel nuts (Inc. inner nuts if applicable)
Tire pressure (Inc. spare tire)
Check front wheels for toe-in
Install clock/voltmeter/room lamp fuse (If applicable)
Install deodorizing filter to air conditioner (If applicable)
Remove wiper blade protectors (If applicable)
UNDER BODY
Manual transmission/transaxle, transfer and differential gear oil level
Brake and fuel lines and oil/fluid reservoirs for leaks
Tighten bolts and nuts of steering linkage and gear box, suspension, propeller shafts and drive shafts
Tighten rear body bolts and nuts (Models with wooden bed only)
ROAD TEST
Clutch operation
Parking brake operation
Service brake operation
Automatic transmission/transaxle shift timing and kickdown
Steering control and returnability
Engine performance
Squeaks and rattles
ENGINE OPERATING AND HOT
Adjust idle speed
Automatic transmission/transaxle fluid level
Engine idling and stop knob operation (Diesel only)
FINAL INSPECTION
Install necessary parts (outside mirror, wheel covers, seat belts, mat, carpet or mud flaps)
Inspect for interior and exterior metal and paint damage
Check for spare tire, jack, tools (wheel chock), and literature
Wash, clean interior and exterior
: Not applicable to this model
PRE-DELIVERY INSPECTION ITEMS
MA-2

Chassis and Body MaintenanceNJMA0005S05Abbreviations: I = Inspect and correct or replace as necessary, R = Replace, L = Lubricate.
MAINTENANCE OPERATIONMAINTENANCE INTERVAL
Reference page Perform either at number of kilome-
ters (miles) or months, whichever
comes first.kmx1,000
(Miles x
1,000)
Months1
(0.6)
—10
(6)
620
(12)
1230
(18)
1840
(24)
2450
(30)
3060
(36)
3670
(42)
4280
(48)
48
Underhood and under vehicle
Brake, clutch & automatic transaxle
fluid (For level & leaks)★IIIIIIII BR-7,AT-13
Brake fluid★R R BR-18
Brake booster vacuum hoses, con-
nections & check valveI I BR-22
Power steering fluid & lines (For
level & leaks)I*1 I I*1 I I*1 I I*1 I ST-7
Brake, clutch & exhaust systemsIIIIIIIIBR-7, FE-10,
FE-26
Manual transaxle gear oil (For level
& leaks)I*1 I I*1 I I*1 I I*1 I MT-15, MT-14
Steering gear & linkage, axle & sus-
pension parts & drive shafts★I*2IIIIST-7,SU-6,SU-7
Outside and inside
Wheel alignment (If necessary,
rotate & balance wheels)IIIISU-7,SU-14
Brake pads, rotors & other brake
components★IIIIIIII BR-27,BR-31
Brake linings, drums & other brake
components★IIIIBR-7
Lock, hinges & hood latch★L*1 L L*1 L L*1 L L*1 L BT-7, BT-16
Seat belts, buckles, retractors,
anchors & adjusterIIIIRS-4
Foot brake, parking brake & clutch
(For free play, stroke & operation)I*1 I I*1 I I*1 I I*1 I BR-12, BR-43, CL-5
Ventilation air filter★Replace every 12,000 km (7,500 miles) or 12 months HA-95 or ATC-128
Supplemental air bag systemsSee NOTE
(1)RS-25
NOTE:
(1) Inspect at the first 10 years, and then every 2 years.
★Maintenance items with “★” should be performed more frequently according to “Maintenance Under Severe Driving Con-
ditions”.
*1: Models except for Australia
*2: Models without three way catalystGI
EM
LC
EC
FE
CL
MT
AT
AX
SU
BR
ST
RS
BT
HA
SC
EL
IDX
PERIODIC MAINTENANCE (EXCEPT FOR EUROPE)
Chassis and Body Maintenance
MA-5

CHASSIS AND BODY MAINTENANCE=NJMA0043S0102Abbreviations: R = Replace I = Inspect: Correct or replace if necessary
MAINTENANCE OPERATIONMAINTENANCE INTERVAL
Refer-
ence
pages Perform on a kilometer basis, but on
an annual basis when driving less than
15,000 km (9,000 miles) in a year.kmx1,000
(miles x 1,000)
Months15
(9)
1230
(18)
2445
(27)
3660
(36)
4875
(45)
6090
(54)
72105
(63)
84120
(72)
96
Underhood and under vehicle
Headlamp aimingIIIIIIIIEL-44
Wheel alignment (if necessary, balance
& rotate wheels)IIIIIIIISU-6/
SU-18
Brake pads, rotors & other brake com-
ponents★IIIIIIIIBR-27/
BR-28
Foot brake, parking brake & clutch (for
free play, stroke & operation)IIIIIIIIBR-12/
BR-44/
CL-9
Brake booster vacuum hoses,
connections, check valveIIIIBR-21
Brake & clutch, systems and fluid (for
level and leaks)IIIIIIIIBR-7
Brake fluid★RRRRBR-7
Power steering fluid and lines (for level
and leaks)IIIIIIIIST-7
Supplemental air bag systems See NOTE (1) RS-25
Ventilation air filter★RRRRHA-95 or
AT C - 1 2 8
Manual transaxle gear oil (check for
leakage. Use genuine NISSAN XZ
gear oil or exact equivalent)IIIIIIIIMT-14
MT-15
Automatic transaxle fluid (for level and
leaks)★IIIIIIIIAT-13
Steering gear & linkage, axle & sus-
pension parts, drive shafts, exhaust
system★IIIIST-7/
SU-6/
SU-18/
FE-10
NISSAN Mobility System See NOTE (2)IIIIIII —
Body corrosion See NOTE (3) BT-6
NOTE:
(1) Inspect after 10 years, then every 2 years.
(2) Check expiration date of the tyre sealant bottle. Replace if necessary.
(3) Inspect once per year.
★Maintenance items with “★” should be performed more frequently according to “Maintenance Under Severe Driving Con-
ditions”.
PERIODIC MAINTENANCE (FOR EUROPE)
Maintenance Schedule for Petrol Engines (Annual Mileage < 30,000 km/year) (Cont’d)
MA-8

CHASSIS AND BODY MAINTENANCE=NJMA0043S0202Abbreviations: R = Replace I = Inspect: Correct or replace if necessary
MAINTENANCE OPERATIONMAINTENANCE INTERVAL
Reference pages Perform on a kilometer basis, but on
an annual basis when driving less
than 20,000 km (12,000 miles) per
year.kmx1,000
(miles x 1,000)
Months20
(12)
1240
(24)
2460
(36)
3680
(48)
48100
(60)
60120
(72)
72
Underhood and under vehicle
Headlamp aimingIIIIII EL-44
Wheel alignment (if necessary, bal-
ance & rotate wheels)IIIIIISU-14
SU-7
Brake pads, rotors & other brake
components★IIIIIIBR-27
BR-28
Foot brake, parking brake & clutch
(for free play, stroke & operation)IIIIIIBR-12
BR-44
CL-9
Brake booster vacuum hoses,
connections, check valveI I I BR-21
Brake & clutch, systems and fluid
(for level and leaks)IIIIII BR-7
Brake fluid★R R R BR-7
Power steering fluid and lines (for
level and leaks)IIIIII ST-7
Supplemental air bag systems See NOTE (1) RS-25
Ventilation air filter★RRRRRR HA-95orATC-128
Manual transaxle gear oil (check for
leakage. Use genuine NISSAN XZ
gear oil or exact equivalent)IIIIIIMT-14
MT-15
Steering gear & linkage, axle & sus-
pension parts, drive shafts, exhaust
system★IIIST-7
SU-6
SU-18
FE-26
NISSAN Mobility System See NOTE (2)IIIII —
Body corrosion See NOTE (3) BT-6
NOTE:
(1) Inspect after 10 years, then every 2 years.
(2) Check expiration date of the tyre sealant bottle. Replace if necessary.
(3) Inspect once per year.
★Maintenance items with “★” should be performed more frequently according to “Maintenance Under Severe Driving Con-
ditions”.
PERIODIC MAINTENANCE (FOR EUROPE)
Maintenance Schedule for Diesel Engines (Annual Mileage < 30,000 km/year) (Cont’d)
MA-10

CHASSIS AND BODY MAINTENANCE=NJMA0043S0402Abbreviations: R = Replace I = Inspect: Correct or replace if necessary
MAINTENANCE OPERATIONMAINTENANCE INTERVAL
Refer-
ence
pages Perform on a kilometer basis only.kmx1,000
(miles x 1,000)15
(9)30
(18)45
(27)60
(36)75
(45)90
(54)105
(63)120
(72)
Underhood and under vehicle
Headlamp aimingIIIIEL-44
Wheel alignment (if necessary, balance
& rotate wheels)IIIISU-6/
SU-18
Brake pads, rotors & other brake com-
ponents★IIIIBR-27
BR-28
Foot brake, parking brake & clutch (for
free play, stroke & operation)IIIIBR-12/
BR-44/
CL-9
Brake booster vacuum hoses,
connections, check valveI I BR-21
Brake & clutch, systems and fluid (for
level and leaks)IIIIBR-7
Brake fluid★R R BR-7
Power steering fluid and lines (for level
and leaks)IIIIST-7
Supplemental air bag systems See NOTE (1) RS-25
Ventilation air filter★RRRRHA-95 or
AT C - 1 2 8
Manual transaxle gear oil (check for
leakage. Use genuine NISSAN XZ
gear oil or exact equivalent)IIIIMT-14
MT-15
Automatic transaxle fluid (for level and
leaks)★IIIIAT-13
Steering gear and linkage, axle & sus-
pension parts, drive shafts, exhaust
system★IIST-7/
SU-6/
SU-18/
FE-10
NISSAN Mobility System See NOTE (2)IIIIIII —
Body corrosion See NOTE (3) BT-6
NOTE:
(1) Inspect after 10 years, then every 2 years.
(2) Check expiration date of the tyre sealant bottle. Replace if necessary.
(3) Inspect once per year.
★Maintenance items with “★” should be performed more frequently according to “Maintenance Under Severe Driving Con-
ditions”.
PERIODIC MAINTENANCE (FOR EUROPE)
Maintenance Schedule for Petrol Engines (Annual Mileage > 30,000 km/year) (Cont’d)
MA-14

CHASSIS AND BODY MAINTENANCE=NJMA0043S0502Abbreviations: R = Replace I = Inspect: Correct or replace if necessary
MAINTENANCE OPERATIONMAINTENANCE INTERVAL
Refer-
ence
pages Perform on a kilometer basis
only.kmx1,000
(miles x
1,000)10
(6)20
(12)30
(18)40
(24)50
(30)60
(36)70
(42)80
(48)90
(54)100
(60)11 0
(66)120
(72)
Underhood and under vehicle
Headlamp aiming I I I EL-44
Wheel alignment (if necessary,
balance & rotate wheels)IIISU-6
SU-18
Brake pads, rotors & other
brake components★IIIIIIBR-27
BR-28
Foot brake, parking brake &
clutch (for free play, stroke &
operation)IIIIIIBR-12
BR-44
CL-9
Brake booster vacuum hoses,
connections, check valveI I BR-21
Brake & clutch, systems and
fluid (for level and leaks)IIIIIIBR-7
Brake fluid★R R BR-7
Power steering fluid and lines
(for level and leaks)IIIIIIST-7
Supplemental air bag systemsSee NOTE
(1)RS-25
Ventilation air filter★RRRRRRHA-95
or ATC-
128
Manual transaxle gear oil
(check for leakage. Use genu-
ine NISSAN XZ gear oil or
exact equivalent)IIIMT-14
MT-15
Steering gear & linkage, axle &
suspension parts, drive shafts,
exhaust system★IIST-7
SU-6
SU-18
FE-26
NISSAN Mobility SystemSee NOTE
(2)IIIIIII —
Body corrosionSee NOTE
(3)BT-6
NOTE:
(1) Inspect after 10 years, then every 2 years.
(2) Check expiration date of the tyre sealant bottle. Replace if necessary.
(3) Inspect once per year.
★Maintenance items with “★” should be performed more frequently according to “Maintenance Under Severe Driving Con-
ditions”.
PERIODIC MAINTENANCE (FOR EUROPE)
Maintenance Schedule for Diesel Engines (Annual Mileage > 30,000 km/year) (Cont’d)
MA-16

NJCL0004
NVH Troubleshooting Chart
NJCL0004S01
Use the chart below to help you find the cause of the symptom. The numbers indicate the order of the inspec-
tion. If necessary, repair or replace these parts.CLUTCH
NJCL0004S0101
Reference page
CL-9
CL-10
CL-11
CL-14
Refer to EM-67, “Removal and Installation” (QG engine model) and
EM-63, “Removal and Installation” (YD engine model).
CL-17 (RS5F30A, RS5F70A), CL-20 (RS5F50A)
CL-22
CL-22
CL-22
CL-22
CL-22
CL-22
CL-22
CL-22
CL-23
CL-23
CL-23
CL-23
SUSPECTED PARTS
(Possible cause)
CLUTCH PEDAL (Free play out of adjustment)
CLUTCH LINE (Air in line)
MASTER CYLINDER PISTON CUP (Damaged)
OPERATING CYLINDER PISTON CUP (Damaged)
ENGINE MOUNTING (Loose)
RELEASE BEARING (Worn, dirty or damaged)
CLUTCH DISC (Out of true)
CLUTCH DISC (Runout is excessive)
CLUTCH DISC (Lining broken)
CLUTCH DISC (Dirty or burned)
CLUTCH DISC (Oily)
CLUTCH DISC (Worn out)
CLUTCH DISC (Hardened)
CLUTCH DISC (Lack of spline grease)
DIAPHRAGM SPRING (Damaged)
DIAPHRAGM SPRING (Out of tip alignment)
PRESSURE PLATE (Distortion)
FLYWHEEL (Distortion)
SymptomClutch grabs/chatters———— 1 —— 2 —— 2 2 2 —— 2 ——
Clutch pedal spongy — 1 2 2 ——————————————
Clutch noisy———— — 1 ————————————
Clutch slips 1 — — — —————— 2 2 —— 3 — 4 5
Clutch does not disen-
gage1234 ——55555——5667—
—: Not applicable
NOISE, VIBRATION AND HARSHNESS (NVH) TROUBLESHOOTING
NVH Troubleshooting Chart
CL-4

SBR686C
Precautions
PRECAUTIONSNJAX0001When installing rubber parts, final tightening must be car-
ried out under unladen condition* with tires on ground.
*: Fuel, radiator coolant and engine oil full. Spare tire, jack,
hand tools and mats in designated positions.
After installing removed suspension parts, check wheel
alignment and adjust if necessary.
Use flare nut wrench when removing or installing brake
tubes.
Always torque brake lines when installing.
Preparation
SPECIAL SERVICE TOOLSNJAX0002
Tool number
Tool nameDescription
HT72520000
Ball joint remover
NT146
Removing tie-rod outer end and lower ball joint
KV38106800
Differential side oil seal
protector
NT147
Installing drive shaft
KV38106800
COMMERCIAL SERVICE TOOLSNJAX0003
Tool name Description
1 Flare nut crowfoot
2 Torque wrench
NT360
Removing and installing each brake piping
a: 10 mm (0.39 in)
FRONT AXLE
Precautions
AX-2

SBR686C
Precautions
PRECAUTIONSNJAX0022When installing each rubber part, final tightening must be
carried out under unladen condition* with tires on ground.
*: Fuel, radiator coolant and engine oil full. Spare tire, jack,
hand tools and mats in designated positions.
Use flare nut wrench when removing or installing brake
tubes.
After installing removed suspension parts, check wheel
alignment.
Do not jack up at the trailing arm and lateral link.
Always torque brake lines when installing.
Preparation
SPECIAL SERVICE TOOLSNJAX0032
Tool number
Tool nameDescription
KV40104710
Drift
NT474
Install ABS sensor rotor
a: 76.3 mm (3.004 in) dia.
b: 67.9 mm (2.673 in) dia.
ST3072000
Drift
NT115
Install ABS sensor rotor
a: 77 mm (3.03 in) dia.
b: 55.5 mm (2.185 in) dia.
COMMERCIAL SERVICE TOOLSNJAX0024
Tool name Description
1 Flare nut crowfoot
2 Torque wrench
NT360
Removing and installing brake piping
a: 10 mm (0.39 in)
REAR AXLE
Precautions
AX-22

FRONT & REAR SUSPENSION
SECTION
SU
CONTENTS
FRONT SUSPENSION<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
110011>2
Precautions <0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
110011[..............2
PRECAUTIONS<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
11001100110011001100110011>2
Preparation <0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
110011[..............2
SPECIAL SERVICE TOOLS........................................2
COMMERCIAL SERVICE TOOLS................................2
Noise, Vibration and Harshness (NVH)
Troubleshooting ...........................................................4
NVH TROUBLESHOOTING CHART............................4
Components<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
1100110011[............5
On-vehicle Service.......................................................6
FRONT SUSPENSION PARTS...................................6
BALANCING WHEELS...............................................7
TIRE ROTATION<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
110011001100110011>7
FRONT WHEEL ALIGNMENT.....................................7
Coil Spring and Shock Absorber .................................9
COMPONENTS<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
11001100110011001100110011>9
REMOVAL AND INSTALLATION...............................10
DISASSEMBLY<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
1100110011001100110011>0
INSPECTION<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
1100110011001100110011001100110011>0
ASSEMBLY<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
110011001100110011001100110011001100110011[ 11
Stabilizer Bar ............................................................. 11
REMOVAL AND INSTALLATION............................... 11
Transverse Link and Lower Ball Joint .......................12
REMOVAL AND INSTALLATION...............................12
INSPECTION<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
1100110011001100110011001100110011>3
Service Data and Specifications (SDS).....................14
GENERAL SPECIFICATIONS (FRONT).....................14
FRONT WHEEL ALIGNMENT (UNLADEN*1).............14
LOWER BALL JOINT...............................................14
WHEELARCH HEIGHT (UNLADEN*1).......................15
WHEEL RUNOUT<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
110011>5
WHEEL BALANCE<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
11>5
REAR SUSPENSION<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
1100110011>6
Precautions <0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
110011[............16
PRECAUTIONS<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
110011001100110011>6
Preparation <0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
110011[............16
COMMERCIAL SERVICE TOOLS..............................16
Noise, Vibration and Harshness (NVH)
Troubleshooting .........................................................16
Components<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
1100110011[..........17
On-vehicle Service.....................................................18
REAR SUSPENSION PARTS...................................18
REAR WHEEL ALIGNMENT.....................................18
Removal and Installation ...........................................20
REMOVAL<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
11001100110011001100110011001100110011001100110011[21
INSTALLATION<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
1100110011001100110011>1
Coil Spring and Shock Absorber ...............................21
REMOVAL AND INSTALLATION...............................21
DISASSEMBLY<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
1100110011001100110011>2
INSPECTION<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
1100110011001100110011001100110011>2
ASSEMBLY<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
110011001100110011001100110011001100110011>2
Torsion Beam, Lateral Link and Control Rod ............23
DISASSEMBLY<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
1100110011001100110011>3
INSPECTION<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
1100110011001100110011001100110011>3
ASSEMBLY<0011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100110011001100
110011001100110011001100110011001100110011>3
Service Data and Specifications (SDS).....................25
GENERAL SPECIFICATIONS (REAR).......................25
REAR WHEEL ALIGNMENT (UNLADEN*).................25
GI
MA
EM
LC
EC
FE
CL
MT
AT
AX
BR
ST
RS
BT
HA
SC
EL
IDX