Chevrolet 1977 light duty truck Service Manual page 193

a procedure for determ ining the presence o f a tire lead
problem.
FRONT ALIGNMENT REQUIREMENTS
Satisfactory vehicle operation m ay occur over a wide
range o f front end wheel alignm ent settings. N ev erthe­
less, should settings vary beyond certain tolerances,
readjustm ents o f alignment is advisable. The specifica­
tions stated in column 1 of the chart in the specifications
section o f this m anual should be used by owners, dealers
and rep airm en as guidelines in vehicle diagnosis either
for repairs under the new vehicle w arranty or for
m a in te n a n c e service at
specifications provide an acceptable all-around operating
range in that they prevent abn orm al tire w ear caused by
wheel alignment.
G overnm en tal Periodic M otor Vehicle Inspection
p rog ram s usually include wheel alignment am ong items
that are inspected. To provide useful in form ation for
such inspections, the specifications stated in column 2 of
the wheel alignm ent chart are given and these are well
w ithin the range o f safe vehicle operation.
In the event the actual settings are beyond the
specifications set forth in column 1 or 2 (whichever is
applicable), or w henever for other reasons the alignment
is being reset, the specifications given in column 3 of the
wheel alignm ent chart should be used.
N OTE: It is good practice
a lignm ent to specifications while the vehicle is in
its
norm ally loaded
consistently operated
have toe-in adjusted with th e truck under heavy
load. This procedure should result in longer tire
life.
CASTER
A D D S H IM S HERE
T O IN C R E A S E C A S TE R
FR A M E
> S U B T R A C T S H IM S HERE
' - T O IN C R E A S E C A STE R
c u s to m e r 's request. These
to set front end
condition. Trucks which are
with heavy loads should
PIVOT SHAFT OUTBOARD OF FRAME
A L IG N M E N T A D J U S T M E N T S
N O TE: A norm al shim pack will leave at least two
(2) threads of the bolt exposed beyond the nut. If
two (2) threads cannot be obtained, check for
dam aged control arms and related parts. The
difference between front and rear shim packs must
not exceed .30 inches. Front shim pack must be at
least .24 inches.
Access to Shim Packs
G 10 -2 0 Models, C IO Models with 3 / 4 " Nut:
W ith vehicle on front end rack, jack at fram e and
raise the wheel off the ground. This will allow the upper
control arm to pivot down far enough to use a socket on
the nuts and perm it shim removal.
G 3 0 Models, C 20 and 30 Models with 7 / 8 " Nut:
Remove the upper control arm bumper; then follow
the same procedure as above. Reinstall the upper control
arm b u m p e r w hen alignm ent is completed.
Caster
All caster specifications are given assuming a fram e
angle o f zero. Therefore, it will be necessary to know the
angle o f the fram e (whether " u p " in rear or "d ow n " in
rear) before a corrected
determined. C am b e r and toe can be read "as is" from
the alignment equipment.
How to Determ ine Caster (Fig. 3A -4)
I. With the vehicle on a level surface, determ ine
the frame angle "B " in Fig. 3A-4, using a bubble
protractor or inclinometer.
FORWARD
caster rea d in g
CAMBER
can be