Chevrolet 70 1969 Series, Shop Manual

Page: 452 / 913

SECTION 9
STEERING SYSTEM
This group is divided into two separate sections as shown in the following index:
Section Subject Page No.
9A Mechanical Steering ......................................................... 9A-1
Steering Linkage ...................................................... 9A-5
Steering Wheel and Steering Column ...................... 9A-9
Mechanical Steering Gear R e p l a c e m e n t ................ 9A-15
9B Power S t e e r i n g ................................................................... 9A-17
Power Steering Gear and Control Valve ................ 9A-20
Trouble Shooting the Power Steering Gear ............. 9A-22
Power Steering Hydraulic Pump ............................. 9A-23
Trouble Shooting the Hydraulic P u m p ................... 9A-27
Power Steering Power C y l i n d e r ................................ 9A-28
Trouble Shooting the Power C y l i n d e r ....................... 9A-30
Tie Rod Anti-Rotation Bushing ................................ 9A-30
Oil C o o l e r ................................................................... 9A-31
Quick Reference Trouble Shooting C h a r t ................ 9A-32
SECTION 9A
MECHANICAL STEERING
Rotation of . the steering wheel is transmitted
to the front axle right and left steering arms from
the steering gear Pitman arm by linkage consist­
ing of rods and levers.
A recirculating ball bearing and sector nut
type steering gear, mounted on left frame side
rail forward of front wheels, is used on all vehicles
covered by this manual.
Steering gear assemblies, while similar in
construction, vary in size and mounting, depending
on truck model application. Refer to "Model Ap­
plication Chart” at end of this section for proper
steering gear application on each truck series.
The major differences in the steering gear
assemblies are described in the following text.
N O T E : Refer to "Steering Gear Adjustments"
later in this section for adjustment of Pitman shaft
lash, back-up adjuster, and worm thrust bearings.
The type 553-D and 554-D steering gear as­
semblies shown in figure 1 have an adjuster as­
sembly at shaft end of gear housing for adjustment
of worm thrust bearing; lip type oil seals at steer­
ing worm and Pitman shaft; shims for adjustment
of Pitman shaft lash, and bushings in gear housing
and side cover. A back-up adjuster is used on the
553-D-17 and 554-D-6 type steering gear to pre­
vent the worm shaft from flexing up and down.
The 568-D type steering gear assemblies shown
in figure 2 have needle bearings in the gear hous­
ing and side cover. Shims are provided between
the housing and end cover or housing and top cover
for adjustment of worm thrust bearings. Packing
and retainer is used in gear housing at Pitman
shaft end. "Stops" are countersunk at each end of
the worm portion of the shaft to prevent worm nut
from bottoming on extreme turns. A back-up ad­
juster is used to keep the worm shaft from flexing
up and down.
STEERING GEAR MAINTENANCE
The following maintenance operations may be
accomplished with the steering gear assembly in­
stalled in the vehicle.
1. At regular intervals, check and if neces­
sary tighten all steering gear mounting bolts,
Pitman arm nut, and gear housing upper cover and
side cover attaching bolts.
2. Lubricate the steering gear and related
linkage as described in L U B R IC A T ION (SEC. 0)
of this manual.
3. Adjust linkage and steering gear assembly
whenever looseness in steering gear indicates
adjustment is required. Refer to "Steering Gear
Adjustments" and "Steering Linkage" later in this
section.
STEERING GEAR ADJUSTMENTS
The steering gear assembly is designed to
provide adjustment to compensate for normal wear
at worm bearings, Pitman shaft, and mating parts.
Before adjustments are made to the steering
gear in an attempt to correct such conditions as
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK SH O P M A N U A L