Chevrolet 10 Series 1970, Service Manual

Page: 524 / 671

STEERING 9-16
brake sh oe-to-d ru m clearan ce; see Hydraulic B rake
Adjustm ent, Sec. 5.
4. W ith wheel and drum assem bly rem oved , steerin g
arm retaining bolt heads a re a ccessib le and rem oval
o f steerin g arm fro m veh icle m ay be accom plished
by rem ovin g retaining nuts.
Installation
1. P la c e steerin g arm in position on veh icle and in stall
retaining bolts. Note that lon ger bolt is in stalled in
fo rw a rd hole.
2. In stall nuts and torque to sp ecification s.
3. P ack wheel bearin gs using a high quality wheel
b earin g lubricant. In sta ll b earin gs and wheel-hub-
brake drum assem bly rem oved p reviou sly.
4. In stall keyed washer and spindle nut. P ro c e e d as
outlined under "F ro n t W heel B earin gs - A dju st" in
Section 3.
5. In stall tie rod b all stud and i f used, steerin g con­
necting rod b all stud, in steerin g arm . Be sure that
the dust c o v e r is in place on b all stud.
6. In stall castellated nut on b all stud, tighten to sp eci­
fication s and in stall c o tter pin.
7. R em ove v e h icle fro m hoist.
8. F ollow in g direction s given in Section 3 to check c o r ­
nering wheel relationship and toe-in ; c o r r e c t as
requ ired .
POWER STEERING
INDEX
Page
General D e s c r i p t i o n .......................................... ................ 9-16
Hydraulic System Checks ................................................
Maintenance and Adjustments .......................... ................
9-16
Component Replacement and R e p a i r s ................................
Pow er Steering Gear A d ju s t m e n t ................ ................
9-16 Pow er Steering P u m p .......................................................
Bleeding Hydraulic S y s te m ............................. ................ 9-17 Pow er Steering G e a r ..........................................................
Fluid L e v e l .......................................................
Pow er C y lin d e r ...................................................................
Pump B elt T e n s io n ..........................................
Pow er Steering H o s e s ......................................................
GENERAL DESCRIPTION
T ru ck pow er steerin g installations are divided into two
ca te g o rie s ; the Conventional System and the In tegral G ear
System . With both system s, hydraulic p ressu re is p ro ­
vided by an en gin e-driven vane-type pump.
W ith the Conventional System (40-60 S e rie s ), hydraulic
p re s s u re is d e liv e re d fro m the pump, through two hoses
to a control v a lv e which senses pow er requirem ent and
supplies the needed hydraulic p ressu re through two addi­
tional hoses to the pow er cylinder. The control v a lve is
a ro ta ry -ty p e va lv e which is mounted d ire c tly to the
s te e rin g g e a r assem bly so that the steerin g shaft, va lve,
w orm sh aft and rack-piston nut are in -lin e.
W ith the In tegral G ear System (10-30 S e rie s ), hydraulic
p re s s u re is d e liv e re d fro m the pump, through two hoses
to the ste e rin g gea r. In the in tegral pow er s teerin g gear,
the steerin g shaft, hydraulic va lv e , w orm and rack-piston
a re a ll in line and within a single housing, making a com ­
pact sp ace-savin g assem bly. With this system there is
no need fo r a separately mounted control va lv e o r pow er
cylin der.
A ll 40-60 S e rie s m odels use a pow er steerin g o il
c o o le r mounted at the fron t of the veh icle.
MAINTENANCE AND ADJUSTMENTS
POWER STEERING GEAR ADJUSTMENT
Sector lash adjustment is the only pow er steerin g gea r
adjustment that can be made on the vehicle. H ow ever, in
o r d e r to make this adjustment, it is also n ecessary to
check the combined valve drag and w orm bearin g preload.
1. Rem ove steerin g connecting rod fro m pitman arm .
2. Loosen s e c to r lash adjusting s c re w locknut and back
o ff adjusting s c re w to the lim it of its tra v e l.
3. D isconnect battery ground w ire and rem ove horn
button cap.
4. Turn the steerin g wheel through its fu ll tra v e l, then
locate wheel at center of its tra v e l.
5. Check combined valve drag and worm bearing p r e ­
load, with an inch-pound torque wrench on the s te e r ­
ing shaft nut, by rotating through the cen ter of tra v e l
(approxim ately 10° in each d irection ). Note the
highest reading.
CHEVROLET TRUCK SERVICE MANUAL