Buick LeSabre 1965 Service Manual page 431

7 - 4 DESCRIPTION CHASSIS SUSPENSION
of lower control arm by links
which have rubber grommets at
both ends to provide flexibility
at the connections and to prevent
rattle.
On the 49000, the lower control
arm assembly consists of two
stamped steel plates welded to-
gether. On the 45, 46, 48000 Se-
ries the l o w e r control arm
consists of a single stamped steel
plate formed to provide maximum
strength. The inner ends of the
lower control arms are bolted to
the frame front cross member
through rubber bushings. The
outer end of each arm is con-
nected to the steering knuckle
with a b a l l socket assembly
pressed in the lower control arm
and bolted to the steering knuckle.
The ball socket can be removed
in service with suitable tools.
To resist fore and ait movement
of the lower control arm in re-
lationship to the frame, two solid
steel brake reaction rods are po-
sitioned between the lower control
arms and front of the frame side
rails. The forward ends of the
rods are rubber mounted to hold
securely to the frame bracket.
The rearward end of the brake
reaction rod attaches to the lower
control arm with two bolts.
Special washers are used under
the bolts and nuts to aid in main-
taining r e q u i r e d torque. The
brake reaction rod must be prop-
erly installed and secured prior
to checking and adjusting caster
and camber.
The upper control arms consist of
a single stamped s t e e l plate
formed to p r o v i d e maximum
s t r e n g t h . Two r e p l a c e a b l e
hardened s t e e l bushings are
threaded into the inner end of
each assembly. Rubber seals are
installed on shafts to exclude dirt
and water from the bearing sur-
faces. Lubrication fittings are
provided at both bearing locations
on upper arm inner shafts. As in
the lower control arms, a ball
joint is positioned through the
outer end of each arm.
The steel forged steering knuckle
accommodates tapered r o l l e r
bearings in the front wheel hubs.
The brake shoe anchor pin is
rigidly bolted to the steering
knuckle. It is not adjustable.
During brake application two
forces act on the front suspen-
sion. When the brakes are ap-
plied, the torque is transmitted
to the backing plate and knuckle
assembly through the brake
shoes, which tends to rotate the
backing plate and knuckle assem-
bly forward. The weight of the
car is thrown forward tending to
move the front of the car down-
ward. This downward motion is
called "front-end dive". In order
to minimize "front-end dive", the
upper c o n t r o l arm shaft i s
mounted to the frame so that the
front end of the shaft is higher
than the rear end at an angle rel-
ative to that of the lower control
arm shaft. Thus, when the brak-
ing force is applied, the tendency
of the car's front end to dive
rotates the backing p l a t e and
spindle assembly in a rearward
d i r e c t i o n , while the braking
torque tends to rotate the backing
plate and spindle assembly in a
forward direction. Therefore, the
braking torque creates an upward
force nearly equal to the down-
ward (diving) force. In this man-
ner, ''front-end dive" is held to
a predetermined minimum. See
Figures 7-1 & 2.
b. Rear Wheel Suspension—
49000 Series
On the 49000 Series, the rear
wheels are not independently
sprung since they are mounted
on axle shafts incorporated into
the rear axle assembly. The rear
wheels are held in proper align-
ment with each other by the rigid
construction of the r e a r axle
housing and by a pair of lower
control arms. With the use of an
open-type drive line, driving and
braking forces are taken by these
control arms. The control arms
are connected to the frame at
their front ends, and to a bracket
welded to the axle housing at the
opposite ends. Both mounting
joints are pivoted through rubber
bushings. See Figure 7-3.
To prevent the axle housing from
rotating about the two lower con-
trol arms during braking and ac-
celeration and to adjust rear
universal joint angle, an adjust-
able, t h i r d c o n t r o l arm i s
mounted between the frame side
rails and axle housing to a brack-
et on the upper right side of the
housing. Adjustment is obtained
through a s e r i e s of vernier-
spaced holes in the two piece
arm. Because of the constant
velocity joints at the center and
rear of the 49000 propeller shaft,
the car is not sensitive to pinion
angle adjustment. If adjustment
is required, see paragraph 6-29.
Two coil type chassis springs are
mounted at an angle forward and
to center of car between the lower
control arm and the frame cross
member at top of kickup. Ride
control is provided by two identi-
cal double direct-acting shock
absorbers angle-mounted between
brackets attached to the axle
housing and to f r a m e c r o s s
member.
To maintain relative position of
the frame side rails and further
prevent rear axle sway, a track
bar is mounted between the track
bar frame bracket on the left and
frame side rail on the right.
Brackets for attaching the track
bar are located with the frame
bracket on the left and the axle
housing bracket on the right. The
track bar is rubber mounted at
each end. See Figure 7-3.
c. Rear Wheel Suspension—
45, 46, 48000 Series
On the 45, 46, and 48000, the rear
w h e e l s are not independently