Isuzu N-Series. Service manual - part 109

SERVICE INFORMATION 00-9

Excessive Tire Wear

1. Improper tire pressure.

1. Properly inflate to recommended pres-

sure.

2. Incorrect tire/wheel usage.

2. Install correct tire/wheel combination.

3. Defective shock absorbers.

3. Repair or replace.

4. Front end out of alignment.

4. Align front end.

5. Loose, worn or damaged steering link-

age, joints, suspension components, 
bushing and ball joints.

5. Inspect, repair or replace as required.

Dual Tires Rubbing

Insufficient wheel spacing.

Check tire and wheel sizes.

PROBLEM

POSSIBLE CAUSE

CORRECTION

00-10 SERVICE INFORMATION

MAIN DATA AND SPECIFICATIONS

Front End Alignment

Power Steering Unit

Wishbone 

Suspension

NHR Rigid

NKR Rigid

NPR

NQR

NPS

Steering Angle

Inner

(deg.)

38.0

°

37.5

°

38.5

°

(7.00-15 

Tire) 

47.5

°

(7.00-16 

Tire) 

42.5

°

(7.50-16 

Tire) 

37.5

°

35.5

°

(7.00-16 

Tire)

42.5

°

(7.50-16 

Tire) 

36.5

°

(8.25-16 

Tire) 

Outer

(deg.)

35.0

°

33.0

°

29.5

°

(7.00-15 

Tire) 

35.0

°

(7.00-16 

Tire) 

32.7

°

(7.50-16 

Tire) 

29.8

°

27.9

°

(7.00-16 

Tire)

32.7

°

(7.50-16 

Tire) 

30.0

°

(8.25-16 

Tire)

Wheel Alignment

Toe-in

mm (in.)

−2−2 (−0.08−0.08)

Camber

(deg.)

0

°15′±45′

1

°15′±45′

0

°15′±45′

0

°15′±45′

0

°15′±45′

0

°15′±45′

Caster

(deg.)

1

°00′±1°

1

°30′±1°

3

°00′±1°

2

°45′±1°

2

°45′±1°

2

°00′±1°

King Pin Incli-
nation

(deg.)

9

°45′±30′

7

°15′

12

°00′

12

°00′

12

°00′

7

°15′

Right Hand Drive

Left Hand Drive

Type

Integral rotary valve type

Number of Ball

28

Gear Ratio

22.6 NKR (Indep)

22.6 NKR (Rigid)

18.8 — 20.9 NPR, NQR, NPS (Rigid)

Ball Screw Lead

mm (in.)

9.172 (0.361) NHR, NKR (Rigid)

9.922 (0.391) NPR, NQR, NPS

9.922 (0.391) NKR (Indep)

Torsion Bar Spring Constant

N

⋅cm/deg (kg⋅cm/deg.)

15.7 (16.0)

Valve Operating Angle

(deg.)

±7°

Regulated Oil Pressure

kPa (kg/cm

2

/psi)

NHR, NKR

10,297 (105/1,439)

NPR, NQR, NPS

11,287 (115/1,635)

Regulated Oil Flow Volume
(minimum)

liter/min (US gal/min / UK

gal/min)

8 (2.11/1.76)

SERVICE INFORMATION 00-11

Power Steering Oil Pump Unit

Tandem Hydraulic Pump

Manual Steering Unit

4J Series Engine

4H Series Engine

Type

Vane type

Theoretical Delivery

(cm

3

/rev)

7.2

8.1

Regulated Oil Flow volume

(liter/min)

8.5 — 6.5

8.0 — 6.5

Regulated Oil Pressure

kPa (kg/cm

2

/psi)

NHR, NKR

10,297 (105/1,493)

10,297 (105/1,493)

NPR, NPS

10,787 (110/1,564)

NQR

11,278 (115/1,635)

Maximum Allowable Speed

(r.p.m)

6,500

6,500

Hydraulic Booster Pump

Power Steering Pump

Type

Vane type

Theoretical Delivery

(cm

3

/rev)

13

8.4

Regulated Oil Flow volume

(liter/min)

8.0

8.0 — 6.5

Regulated Oil Pressure

kPa (kg/cm

2

/psi)

11,770 (120/1,706)

10,790 (110/1,564)

Maximum Allowable Speed

(r.p.m)

6,500

NHR, NKR

NPR, NQR

Type

Recirculating ball type

Sector Shaft Outside Diameter

mm (in.)

34.295

38.1

Number of Ball

28 

× 2

50 

× 2

Gear Ratio

24.5 — 28.5

27.7 — 31.7

00-12 SERVICE INFORMATION

SERVICE STANDARD

ITEMS

SERVICE STANDARD

SERVICE LIMIT

Power Steering

Sector Shaft Outside Diameter

mm (in)

RHD&LHD

39,975 (1.574)

Play between Sector Shaft and 
Bearing

mm (in)

RHD

—

0.12 (0.0047)

LHD

—

0.20 (0.0080)

Backlash between Sector 
Shaft and Ball Nut

mm (in)

RHD&LHD

0.12 (0.0047)

Steering Wheel Free Play

mm (in)

10 — 50 (0.4 — 2.0)

Power Steering Fluid Pressure
(at idling engine speed)

kPa (kg/cm

2

/psi)

NQR without HBB

11,278 (115/1,635)

NPR/NPS/NQR with HBB

10,787 (110/1,564)

except Above Models

10,297 (105/1,493)

Manual Steering

Sector Shaft Outside Diameter

mm (in)

NHR, NKR

34.925 (1.375)

34.825 (1.371)

NPR, NQR

38.100 (1.500)

38.000 (1.496)

Play between Sector Shaft and 
Needle Bearing

mm (in)

—

0.2 (0.008)

Ball Nut Axial Play

mm (in)

—

0.1 (0.004)

Worm Shaft Starting

Torque

N

⋅m (kg⋅m/lb⋅ft)

(Without Sector Shaft)

NHR, NKR

0.34 — 0.64 (0.035 — 0.065/

0.25 — 0.47)

NPR, NQR

0.29 — 0.69 (0.030 — 0.070/

0.22 — 0.51)

(With Sector Shaft)

NHR, NKR

0.54 — 1.03 (0.055 — 0.105/

0.40 — 0.76)

NPR, NQR

0.98 (0.1/0.72) or less

Backlash between Sector 
Shaft and Ball Nut

mm (in)

NHR, NKR

0.2 (0.0079) or less

NPR, NQR

0.5 (0.0197) or less

Steering Wheel Free Play

mm (in)

10 — 30 (0.4 — 1.2)

Suspension

Spring Pin Outside Diameter

mm (in)

25 (0.98)

24.7 (0.019)