Chevrolet CHEVY VAN G10 SERIES Service Manual page 283

G en e ra l D e s c r i p t i o n .................................................................9 -1 7
M a in te n an ce a n d A d ju s tm e n ts ............................................ 9 -1 7
A d ju stm en ts ...........................................................................9-1 7
P o w e r S teerin g G e a r ...................................................... 9 -1 7
P u m p B elt T e n s i o n .........................................................9-18
F lu id L evel ...........................................................................9 -1 8
The p o w e rin g steering gear is sim ila r
steering gears in general design and is overhauled in a like
m anner. The gear incorporates the recirculating ball system in
w hich steel balls act as a rolling thread betw een the steering
w orm shaft and rack-piston. The rack-piston n u t is geared to
the sector o f the p itm an shaft. The valve is contained in the
gear housing thus elim inating the need for separately m ounted
valve and cylinder assemblies.
Variable ratio steering is faster nearer th e corners, requiring
fewer turns o f the steering wheel to move the fro n t wheels
from stop to stop, while steering effo rt is n o t increased. It also
provides more precise control and b etter response in m an­
euvering, particularly in sharp rapid turns and in parking.
Variable ratio steering is accom plished b y a pitm an shaft
sector incorporating a short to o th on eith er side o f a long
center to o th , rath er th an a sector w ith three teeth o f equal
length as in the constant ratio gear (fig. 28). C om panion
changes are also made in the rack-piston teeth.
H ydraulic pressure is provided by an engine-driven vane-
type pum p which is bracket m ounted to the left side o f the
MAINTENANCE AND ADJUSTMENTS
ADJUSTMENTS
Power Steering Gear
The over-center adjustm ent (fig. 29) is the only pow er
steering gear adjustm ent w hich can be m ade o n the car.
However, in order to make this adjustm ent, it is also necessary
to check the com bined ball and th ru st bearing preload.
1. Remove the pitm an shaft n u t. Mark the relation o f the
pitm an arm to the pitm an shaft. Disconnect the pitm an
arm from the pitm an shaft using Puller Tool J-6632
(fig- !)•
2. Loosen th e pitm an shaft adjusting screw lo ck nu t and
th read the adjusting screw out to the limit o f its travel
through the side cover.
3. D isconnect the b attery ground cable.
4. Remove th e horn b u tto n .
5. Turn the steering wheel through its full travel, then
locate th e wheel at its center o f travel.
POWER STEERING
P ag e
B leeding H y d ra u lic S ystem ............................................9 -1 8
H y d ra u lic System C heck s .............................................. 9-18
C o m p o n en t R e p la c e m e n t a n d R e p a i r s ..........................9 -1 9
P o w er S teering G e a r ........................................................... 9 -1 9
GENERAL DESCRIPTION
to o th e r po w e r
engine. Pressure is delivered from the pum p through tw o hoses
to the variable ratio steering gear.
6
7.
8
9.
P ow er S teering P u m p .........................................................9 -2 0
P o w er S teering H o s e s .........................................................9 -2 0
P IT M A N S H A F T SECTOR
RACK PISTON
CONSTANT RATIO
Fig. 2 8 —Pitm an Shaft Sector Teeth
. Check the com bined ball and th rust bearing preload with
an inch-pound torque wrench on the steering shaft n u t
by rotating through the center o f travel (approxim ately
1/4 tu rn in each direction). N ote the highest reading.
Tighten the p itm an shaft adjusting screw and check
torque at steering shaft n u t until over-center preload and
to ta l steering gear preload falls w ithin specifications.
Refer to torque specifications at rear o f m anual for
correct torque values.
. Install horn b u tto n and connect the b attery ground
cable.
C onnect the pitm an arm to the pitm an shaft, lining up
th e marks made at removal.
C A U T IO N : The pitman arm to pitman shaft fast­
ener is an im portant attaching part in th at it could
affect the performance o f vital components and
systems, and/or could result in major repair ex­
pense. It must be replaced w ith one of the same part
STEERING 9-17
P ag e
VARIABLE RATIO
C H E V Y V A N SHOP M A N U A L