Pontiac FIREBIRD 1972 Service Manual page 1164

STEERING 9-1 1
DESCRIPTION
MANUAL STEERING GEAR
The ball nut, mounted on the worm, is driven through
steel balls which circulate in helical grooves in both the
The manual steering gear (Fig. 9-7) is of the recirculating
worm and nut. Ball return guides, akacned to the nut,
ball nut type with the steering shaft, worm shaft and worm
serve to recirculate the two sets of twenty-five balls each
in the grooves.
nut all in line, making a compact and easily serviced gear.
The steering shaft and worm shaft are separated with a
flexible coupling which permits removal of the gear as-
sembly or steering shaft (and column) independent of each
other.
The mechanical element of this steering gear is a low-
friction, high-efficiency recirculating ball system in which
steel balls act as a rolling thread between the steering
worm and nut. The nut is one piece and is geared to the
sector of the pitman shaft. Lash between the pitman shaft
and rack piston nut is maintained by an adjusting screw
which is retained in the end of the pitman shaft gear (Fig.
As the steering wheel is turned to the right, the nut moves
upward. When the wheel is turned to the left the nut
moves downward.
The teeth on the sector, which are forged as part of the
pitman shaft, and the ball nut are so designed that a
tighter fit exists between the two when the front wheels are
straight ahead. Proper engagement between the sector and
the ball nut is obtained by an adjusting screw which moves
the pitman shaft endwise, permitting desired engagement
of the tapered teeth of the ball nut and sector gear. The
worm bearing adjuster can be turned to provide proper
9- 8).
preloading of the upper and lower bearings.
W O R M B E A R I N G
ADJUSTER L O C K N U T
I
P I T M A N S H A F T
/
L O W E R B ~ A R I N G WORM'SHAFT B A L L NUT G U I ~ E
CLAMP 'BALL
RETURN GUIDE ATTACHING FLANGE
Fig. 9-7 Cross Section of Manual Steering Gear
POWER STEERING GEAR
DESCRIPTION
All series use a variable ratio power steering gear. Variable steering effort is not increased. It also provides more pre-
ratio steering is faster, requiring fewer turns of the steering cise control and better response in maneuvering, particu-
wheel to move the front wheels from stop to stop, while larly in sharp rapid turns and in parking.