Chevrolet 1977 light duty truck Service Manual page 194

2. Draw a graphic
representative o f the fra m e angle (either " u p " in rear or
"d ow n" in rear).
3. D eterm ine the caster angle from the alignment
equipm ent and draw a line that is representative o f the
caster reading.
4. To determine an
re ad in g " with various fra m e angles and caster readings,
one of the following rules applies:
a. A DOWN IN REAR" frame angle must be
SUBTRACTED from a POSITIVEcaster reading.
b. An UP IN REAR" fram e angle must be
ADDED to a POSITIVE caster reading.
c. A "DOWN IN REAR" fram e angle must be
ADDED to a NEGATIVE caster reading.
d. An "U P IN REAR" fram e angle must be
SUBTRACTED from a NEGATIVE caster reading.
How to Adjust Caster
5. Add or subtract as necessary to arrive at the
corrected caster angle.
6. Measure dim ension " A " (bum p stop bracket to
fram e) and check the specifications for that dimension.
7. Correct the actual caster angle, as arrived at in
Step 4, as necessary to keep within the specifications by
" B " IS LESS T H A N " A " W H E N W H E ELS T O E -IN
Fig. 3A-3-Toe-In A d justm ent
as in Fig. 3A-4 that is
"actual (corrected) caster
a dding or subtracting shims from the front or rear bolt
on the upper control arm shaft, shown in Figure 3A-2.
Camber
1. D eterm ine the cam ber angle from the align­
ment equipment.
2. Add or subtract shims from both the front and
rear bolts to affect a change.
Toe-In
1. D etermine the wheel toe-in from the alignment
equipment.
2. Change the length of both tie rod sleeves to
affect a toe change.
Toe-in can be increased or decreased by changing
the length o f the tie rods. A threaded sleeve is provided
for this purpose.
W hen the tie rods are mounted ahead o f the
steering knuckle they must be decreased in length in
order to increase toe-in. W hen the tie rods are mounted
behind the steering knuckle they must be lengthened in
order to increase toe-in.
See Section 3B for proper tie rod clamp orientation
and positioning.