Buick LeSabre 1965 Service Manual page 466

8 - 2 MANUAL STEERING
STEERING GEAR, STEERING COLUMNS AND LINKAGE
b. Steering Gear Specifications (Cont'd)
Items Specifications
Number and Type of Worm Shaft Bearings 2 Ball Bearings
Worm and Nut Balls - No. and Diameter 50, 9/32"
Lash Adjusting Screw and Shim Clearance in Pitman Shaft 0 to .002"
Adjustments
Worm Bearing Preload
Torque at Worm or Steering Shaft 5 to 9 in.lbs.
Lbs. Pull at Steering Wheel Rim 62 to 1.2 lbs.
Pitman Shaft "Overcenter"
Torque at Worm or Steering Shaft 5 to 11 in. lbs. Higher than Worm Bearing Preload
Lbs. Pull at Steering Wheel Rim 1/2 to 1 lb. Higher than Worm Bearing Preload
Total "Overcenter" Pull Should Not Exceed 18 in. lbs. or 2.3 lbs.
8 - 2 DESCRIPTION OF
MANUAL STEERING
GEAR
The steering gear is the recir-
culating ball worm and nut type.
The worm on lower end of the
steering shaft and the ball nut
which is mounted on the worm
have mating spiral grooves in
which steel balls circulate to pro-
vide a low-friction drive between
worm and nut. See Figure 8-1.
Two sets of 25 balls are used,
with each set operating independ-
ently of the other. The circuit
through which each set of balls
circulates includes the grooves
in worm and ball nut and a ball
return guide attached to outer
surface of nut.
When the wheel and steering shaft
turn to the left the ball nut is
moved downward by the balls
which roll between the worm and
nut. As the balls reach the outer
surface of nut they enter the re-
turn guides which direct them
across and down into the ball nut,
where they e n t e r the circuit
again. When a right turn is made,
the ball nut moves upward and the
balls circulate in the reverse di-
rection. See Figure 8-1.
Teeth on the ball nut engage teeth
on a sector forged integral with
the pitman shaft. The teeth on the
ball nut are made so that a "high
point" or tighter fit exists be-
tween the ball nut and pitman shaft
WORM
BEARING
ADJUSTER
PITMAN SHAFT
SECTOR
WORM SHAFT
/ WORM
BEARING
WORM
SEAL
BALL NUT
GUIDE
Figure 8-1—Steering Gear Worm and Ball Nut
sector teeth when front wheels
are in the straight-ahead position.
The teeth of sector are slightly
tapered so that a proper lash may
be obtained by moving the pitman
shaft endways by means of a lash
adjuster screw which extends
through the gear housing side
cover. The head of a d j u s t e r
screw and a selectively fitted
shim fit snugly into a T-slot in
the end of the pitman shaft, so
that the screw also controls end
play of shaft. The screw is locked
by an external lock nut. See Fig-
ure 8-2.
The pitman shaft is carried by a
bushing in the steering gear hous-
ing and a bushing in the housing
SHIM
ADJUSTING SCREW
LOCK NUT
SIDE COVER
BUSHINGS
WORM
PITMAN SHAFT
SEAL
Figure 8-2—Steering Gear Pitman
Shaft and Ball Nut