1995 ISUZU TROOPER Workshop Manual

DIAGNOSIS 3-9
TIRE DIAGNOSIS
• Hard cornering • Incorrect wheel alignment • Heavy acceleration
from a
stop • Under inflation
• Tire unevenly worn
• Lack of rotation • Over inflation
Fig. 3-1
IRREGULAR AND PREMATURE WEAR
(Fig. 3-1)
Irregular and/or premature wear has many causes.
Some of them are incorrect inflation pressures, lack of
tire rotation, poor driving habits or improper wheel
alignment. Incorrect inflation
is common cause of tire
premature wear.
NOTE:
Due to their design, radial tires tend to wear faster in
the
shoulder area, particularly on the front tires. This
makes
regular rotation especially necessary. After
rotation,
be 'Sure to check wheel nut torque, and set tire
pressures.
TIRE ROTATION (Fig. 3-2)
Tire rotation is recommended to equalize wear for
longer tire life.
Acceptable rotation patterns
Fig. 3-2
Spare tire
If the following conditions are noted, rotate the tires:
• Front tire wear is different from rear.
• Uneven wear exists across the tread of any tire.
• Left and right front tire wear is unequal.
•
Left and right rear tire wear is unequal.
Check wheel alignment if the following conditions are
noted:
• Left and right front tire wear is unequal.
•
Wear is uneven across the tread of any front tire.
• Front tire treads have a scuffed appearance with
"feather" edges on one side of the tread ribs or
blocks.
TREAD WEAR INDICATORS (Fig. 3-3)
The original equipment tires have built-in tread wear
indicators to show when tires need replacement.
These indicators may appear as wide bands. When the
indicators appear in
two or more grooves at three
locations, tire replacement is recommended.
Fig. 3-3
Tread wear
indicators

3-10 DIAGNOSIS
RADIAL TIRE WADDLE (Fig. 3-4)
Fig. 3-4
Waddle is side-to-side
movement at the front and/or
rear of the car. It can be caused by the steel belt not
being straight within the tire, or by excessive lateral
runout of the tire or wheel. It is most noticeable at low
speed, about 8 to 48 km/h (5 to 30 mph). It may also
cause
rough ride at 80 to 113 km/h (50 to 70 mph).
The car can be road tested
to see which end of the car
has
the faulty tire. If the tire causing the waddle is on
the rear, the rear end
of the car will "waddle". From
the
driver's seat, it feels as if someone is pushing on
the side
of the car.
If the faulty tire is on the front, the waddle is more
easily seen. The front sheet metal appears to be
moving back and forth. It feels as if the driver's seat
is
the pivot point in the car.
Another more time-consuming method of
determining the faulty tire is substituting tire and
wheel assemblies
that are known to be good. Follow
these steps:
1. Drive the car to determine if the waddle is
coming from the front or rear.
2. Install tire and wheel assemblies known to be
good (from a similar car) in place ofthose on the
end
of the car which is waddling. If the waddle
cannot be isolated to front or rear, start with the
rear tires.
3. Road test again. If improvement is noted, install
the original tire and wheel assemblies one at a
time until the faulty tire is found. If no
improvement is noted, install tires known to be
good in place of all four. Then, install the originals
one at a
time until the faulty tire is found.
RADIAL TIRE LEAD/PULL (Fig. 3-5)
"Lead/Pull" is vehicle deviation from a straight path,
on a level road
with no pressure on the steering
wheel.
Lead is usually caused by:
1. Poorly manufactured radial tires.
2. Uneven brake adjustment.
3. Wheel alignment.
The
way in which a tire is built can produce lead in a
car.
An example of this is placement of the belt. Off­
center belts on radial tires can cause the tire to
develop a side force while rolling straight down the
road and the tire will tend to roll like a cone.
The
"Radial Tire Lead/Pull Correction" chart (Fig. 3-5)
should be used to make sure that front wheel
alignment is not mistaken for tire lead.
Rear
tires will not cause lead/pull.
II

DIAGNOSIS 3-11
I RADIAL TIRE LEAD/PULL CORRECTION CHART I
I INFLATE TIRES TO RECOMMENDED I
PRESSURE
I
ROAD TEST VEHICLE ON LEVEL
I UNCROWNED ROAD
I SWITCH FRONT TIRES SIDE TO SIDE I
AND ROAD TEST AGAIN
LEADS IN
SAME LEAD CORRECTED LEAD REVERSES
DIRECTION
IF ROUGHNESS RESULTS, DIRECTION
REPLACE TIRES.
PUT TIRES
BACK IN INSTALL KNOWN GOOD
ORIGINAL POSITION
TIRE ON
AND CHECK ALIGNMENT ONE FRONT SIDE
LEAD CORRECTED LEAD REMAINS. INSTALL
REPLACE TIRE
A KNOWN GOOD TIRE IN
PLACE OF OTHER FRONT TIRE
LEAD CORRECTED
REPLACE TIRE
Fig. 3-5

MEMO

FRONT END ALIGNMENT 3A-1
SECTION3A
FRONT END ALIGNMENT
CAUTION:
When fasteners are removed, always reinstall them at the same location from which they were removed. If
a fastener needs to be replaced, use the correct part number fastener for that application. If the correct part
number fastener is not available, a fastener of equal size and strength (or stronger) may be used. Fasteners
that are not reused, and those requiring thread locking compound will be called out. The correcttorque value
must be used when installing fasteners that require it. If the above conditions are not followed, parts or
system damage could result.
CONTENTS
General Description ................................ 3A-1
Camber Adjustment ............................. 3A-4
Definition of Terms .............................. 3A·2 Toe-in Adjustment ............................... 3A-5
On-Vehicle Service ................................. 3A-3 Maximum Steering Angle Adjustment ....... 3A-5
Inspection ......................................... 3A-3 Main Data and Specifications ..................... 3A-6
Trim Height Adjustment ........................ 3A-3 General Specifications .......................... 3A-6
Caster
Adjustment ............................... 3A-3 Torque Specifications ........................... 3A-6
GENERAL DESCRIPTION
"Front End Alignment" refers to the angular
relationship between the front wheels, the front
suspension attaching parts and the ground.
Proper front end alignment must be maintained in
order to insure efficient steering, good directional
stability and to prevent abnormal tire wear.
The
most important factors of front end alignment are
wheel toe-in, wheel camber and axle caster.

3A-2 FRONT END ALIGNMENT
DEFINITION OF TERMS
CAMBER (Fig. 3A-1)
Camber is the inward or outward tilting of the front
wheels from the vertical. When the wheels tilt outward
at the top, the camber is
positive(+). When the wheels
tilt inward at the top, the camber is negative(-). The
amount
of tilt measured in degrees from the vertical is
called the camber angle.
If camber is extreme or unequal between the wheels,
improper steering and excessive tire
wear will result.
Negative camber causes
wear on the inside of the tire,
while positive camber causes wear to the outside.
Left front view
Positive direction
Fig. 3A-1
CASTER (Fig. 3A-2)
Caster is the tilting of the wheel axis either forward or
backward from the vertical (when viewed from the side
of the vehicle). A backward tilt is positive(+) and a
forward tilt is
negative(-).
On the short and long arm type suspension you cannot
see a caster angle
without a special instrument, but if
you look straight down from the top of the upper
control arm to the ground, the
ball joints do not line up
(fore and aft) when a caster angle other than
0 degree is
present. With a positive angle, the lower
ball joint
would be slightly ahead (toward the front of the
vehicle)
of the upper ball joint center line .
• Front
Fig. 3A-2
TOE-IN (Fig. 3A-3)
Toe-in is the turning of the front wheels. The actual
amount of toe-in is normally a fraction of a degree.
Toe-in is measured
from the center of the tire treads or
from the inside of the tires. The purpose of toe-in is to
insure
parallel rolling of the front wheels and to offset
any
small deflections of the wheel support system
which occurs
when the vehicle is rolling forward.
lncorrecttoe-in results in excessive toe-in and unstable
steering. Toe-in is the last alignment to
be set in the
front end alignment procedure.
Fig. 3A-3
•