Chevrolet 70 1969 Series, Shop Manual

Page: 123 / 913

FRONT SUSPENSION 3A-4
N O T L E V E L the frame angle (fig. 2) must be de­
termined and added to the caster angle to obtain a
true caster reading.
1. Position vehicle on a smooth level surface.
2. Using a bubble protractor (fig. 2), measure
the frame angle (FA). Frame angle is the degree
of tilt in the frame from the level position. Neg­
ative frame angle is when the frame is high (above
level) in the rear. Positive frame angle is when the
frame is low (below level) in the rear.
3. Determine the caster angle for the left
wheel using the alignment equipment.
4. Add the frame angle (FA) found in step 2
to the left wheel caster reading found in step 3 to
determine the "corrected caster" for left wheel.
To determine "corrected caster" with various
frame and caster readings the following rules
apply:
(a) Negative frame angle must be added to
positive caster reading.
(b) Positive frame angle must be subtracted
from positive caster reading.
(c) Negative frame angle must be subtracted
from negative caster reading.
(d) Positive frame angle must be added to
negative caster reading.
Example: An HV-70 with power steering has
a left wheel caster reading of 2°
positive, but the frame angle is neg­
ative (high in the rear) 1/2°; there­
fore, 1/2° negative frame angle plus
2° positive caster gives 2-1/2°
positive as the "corrected caster"
for that wheel. Referring to "Speci­
fications," we find that 2-1/2° posi­
tive caster is within the specified
setting.
5. Repeat steps 2 through 4for the right wheel.
6. If the caster is not within specifications,
caster can be corrected by adding or removing
caster shims between the axle and spring.
KING PIN INCLINATION
King pin inclination is the amount that top of
king pin is inclined toward center of vehicle. King
pins are inclined (B, fig. 1), to decrease friction
between tires and road when turning. Precision
instruments must be used to check king pin inclin­
ation when axle is installed in vehicle. When axle
is removed, check can be made on bench as follows:
Referring to figure 3, place two uniform blocks
on flat surface and rest spring seats on blocks.
Using a square and protractor as shown, project
the proper degree line (see "Specifications") from
center reference point of protractor to upper end
of square. Place square on bench adjacent to axle
king pin. Measure distance from king pin at top
and bottom to scribed line on square. If a differ­
ence is noted, axle is sprung. To determine degree
of distortion, subtract smaller reading fronrfarger.
Straightening of axle center to correct king pin in­
clination will also change the camber. Recheck
camber after correcting king pin inclination. If
axle is bent or twisted, refer to " F R O N T A X L E "
(SEC. 3B) for corrective information.
Figure 3 — Checking King Pin Inclinition
Using Square and Protractor
FRONT END ALIGNMENT SPECIFICATIONS
Truck Models
H V , JV-70,
HM-80
TV-70
H V , JV-70
H M , JM-80
TV-70
TM-80
Axle Model F070
F070 F090 F090 F090
Camber (Degrees).................
Caster (Degrees)....................
King Pin Inclination (Degrees) .
Toe-In—Inches.......................
L. + 1 1/2° ± 1/2°
R. + 1 1/2° ± 1/2°
+ 2 3/4° ± 1/2°
L. 7 1/6
R. 7 1/6°
1/8" to 1/4”
+ 1 1/2“ ± 1/2°
+ 1 1/2° ± 1/2°
+ 1 1/4° ± 1/2°
7 1/6°
7 1/6°
1/8" to 1/4"
+ 1/4“ ± 1/2°
- 1/4° ± 1/2°
+ 1° ± 1/2°
4 3 /4 “
6 1/4°
1/8" to 1/4"
+ 1/4° ± 1/2
- 1/4° ± 1/2°
+ 1 1/4“ ± 1/2°
5 3/4°
6 1/4°
1/8" to 1/4"
+ 1/4“ ± 1/2“
- 1/4° ± 1/2°
0 + 1/2
L. 5 3 /4 “
R. 6 1/4“
1/8" to 1/4”
Truck Models
TV-70 TM-80
H V , JV-70,
H M , JM-80
JM-80
Axle Model FI 10 F110 F120 F160
Caster (Degrees)..........................................
King Pin Inclination (Degrees)
+ 1/4“ ± 1/2“
- 1/4° ± 1/2°
+ 1 1/4° ± 1/2°
5 3/4°
6 1/4°
1/8" to 1/4"
+ 1/4“ ± 1/2“
- 1/4° ± 1/2°
0 + 1/2°
5 3/4°
6 1/4°
1/8" to 1/4”
L.S. + 1/4“ ± 1/2
R.S. - 1/4° ± 1/2°
1° + 1/2°
L. 5 3/4°
R. 6 1/4°
1/8” to 1/4"
+ 1“ ± 1/2“
+ 1° ± 1/2°
1“ + 1/2°
R. & L. 8“
1/8" to 1/4”
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK SH O P M A N U A L