Buick LeSabre 1965 Service Manual page 438

CHASSIS SUSPENSION
TROUBLE DIAGNOSIS 7 - 1 1
attempt to improve riding condi-
tions that were actually standard,
or that erroneous methods were
used in judging the operating con-
dition of the units.
Before attempting to test shock
absorbers make sure that all at-
taching bolts and nuts are tight.
Tires should be uniformly inflated
to specified pressure (par. 1-2).
The chassis should be well lubri-
cated to make sure that suspen-
sion parts are free moving.
Test each front and rear shock
absorber in turn by quickly push-
ing down and then lifting up on the
end of the car bumper adjacent
to the unit being checked. Use the
same force as near as possible
on each test, and note the amount
of resistance provided by the
shock absorber on compression
and rebound. A little practice on
another car of the same model
which has satisfactory ride con-
trol will aid in judging the amount
of resistance that should exist.
Both front shock absorbers should
provide the same feeling of re-
sistance and both rear shock ab-
sorbers should do likewise. Any
noticeable variation between right
and left shock absorbers indicates
that one unit is not operating nor-
mally. Little or no resistance on
compression or rebound indicates
air in shock absorbers, internal
leakage due to wear, or that the
valve is held open by dirt. Ex-
cessive resistance indicates that
bleeder hole in valve is plugged
with dirt.
If there is any doubt about the
action of a shock absorber after
testing as described above, re-
move the unit from car. Mount
it vertically in vise with safe jaws
gripping the mounting eye firmly,
then move the piston rod up and
down by hand. There should be no
free movement in this test. Lack
of resistance to movement indi-
cates air in the shock absorber,
internal leakage due to wear, or
that the valve is held open by dirt.
A faulty shock absorber must be
replaced as it cannot be disas-
sembled for repairs.
In the test given above, the amount
of force that can be applied is not
sufficient to open a valve against
its spring pressure; therefore,
this test only checks the flow of
fluid through the valve bleeder
hole as well as any leakage due
to a valve being held open, or due
to internal wear of piston and
cylinder. Since it is unlikely that
the valve springs will weaken in
service, it may be assumed that
the shock absorber action is nor-
mal if it operates satisfactorily in
the test given above.
c. Loose Ball Joints
The upper ball stud is spring -
equipped and thus preloaded in
its socket at all times. This min-
imizes looseness at this point and
compensates for normal wear. If
the upper stud has any perceptible
lateral shake during testing, or if
it can be twisted in its socket
with the fingers, the upper ball
joint should be replaced.
The lower ball joint is not spring
loaded but firmly seated by the
weight of the car. With the chas-
sis spring load removed from the
ball joint, this ball joint may
show looseness. Such looseness
is probably due to normal operat-
ing clearance. The following test
procedure will accurately indi-
cate condition of ball joints:
1. Place jack under lower control
arm as far outboard as possible
and still have access to the lower
ball joint grease fitting. Be sure
the upper control arm does not
contact the rebound bumper when
the car is raised. Raise car until
front wheel clears the floor.
2. Remove lower ball joint grease
fitting and install Gauge J-21240.
3. Place a pry bar between floor
and tire and raise tire. This puts
a load on the ball joint.
4. Repeat procedure s e v e r a l
times and take maximum and
minimum gauge readings under
load and no load conditions.
5. Subtract minimum r e a d i n g
from maximum reading. If dif-
ference is more than .100", re-
place ball joint.
6. With car still supported as
above, attempt to move upper ball
joint from side to side in its
socket. If joint can be shaken
laterally or if it can be twisted
in its socket with the fingers,
need for replacement is indicated.
7 - 6 IMPROPER STEERING
ACTION
Steering action is dependent upon
the chassis suspension members
as well as the steering gear as-
sembly and tie rods. Improper
steering actions which are most
likely to be caused by chassis
suspension are covered in this
paragraph, while conditions most
likely to be caused by the steering
gear assembly or tie rods are
covered in paragraph 8-3.
a. Car Pulls or Leads
to One Side
(1) High crowned roads.
(2) Low or uneven tire pressure
(par. 1-2).
(3) Front tires of unequal diam-
eter due to wear.
(4) Brakes dragging on one side
(par. 9-8).
(5) Shock absorbers leaking or
inoperative (par. 7-5).
(6) Incorrect caster, camber, or
toe of front wheels (par. 7-18).
(7) Frame bent or broken.
b. Steering Affected by
Application of Brakes
(1) Oil or other foreign matter on
brake lining. See paragraph 9-6.
(2) Low or uneven tire pressure
(par. 1-2).