Chevrolet DB90 Series, Service Manual

Page: 43 / 242

S ec. 4B -37
REAR SPRINGS AND SUSPENSION
Figure
4 —A ir Suspension System
CONTROL ARM INSTALLATION
IMPORTANT: B efo re final torquing of control
a rm -to -fra m e bracket pivot b olts and nuts, the
rea r suspension should be at norm al ride height.
If connections a re tightened without fir s t obtaining
th is adjustment, a torsion al preload w ill be im ­
posed on rubber bushings when the fram e a ssu m es
norm al height relative to axle.
1. P osition D elrin lin e r s, one on top and one
at bottom of control arm . T h ese can be held in
p la ce with m asking tape w hile installing control
arm . TAPE MUST NOT BE BETWEEN BRACKET
AND LINER.
2. See that dowel pin hole is clean in control
arm and axle b racket. If previou sly rem oved, in­
s e r t dowel pin and r a ise control arm into position
at fram e bracket and lo o se ly in sta ll pivot bolt.
R a ise control arm , at axle, then lo o se ly in sta ll
anchor plate and attaching U -b olts and nuts.
3. Install b olts and nuts attaching bellow s sup­
port bracket to control arm and torque to "Speci­
fication s."
4. E stab lish v eh icle at norm al ride height by
jacking up fram e. R efer to dim ension "A" to "B"
in figure 4.
5. Initially tighten control arm pivot b olts and
U -bolt nuts.
6. Tighten both control arm s e ts c r e w s ap­
p roxim ately equal distance and torque to "Speci­
fication s."
7. Final torque control arm pivot bolts and
U -bolt nuts to "Specifications."
HM8721B SUSPENSION
DESCRIPTION
R ear sp rin gs are se m i-e lip tic type with com ­
bined au xiliary spring (fig. 5). A ll spring hangers
and b rack ets are bolted to the fram e. A uxiliary
sp rin g is mounted on top of main spring and con­
ta c ts sep arate b rackets bolted to fram e sid e rail.
Springs a re attached to axle housing with U -b o lts.
A sep arate spring seat is used between spring and
a xle and is held in p lace by the spring U -b o lts and
bottom plate. A sep arate radius rod eye bracket is
held in p lace at forw ard sid e of axle housing by the
sp rin g se a t, U -bolt and bottom p la te. A rubber
a x le bumper is bolted to fram e above axle housing.
R ear springs a re shackled at rear end as i l ­
lu strated in figure 6. Shackle stud is secu red in
sh ack le bracket by a nut and w asher, and shackle
is retained on stud by a clam p ring (nut) and clamp
bolt.
Radius rod front bracket is integral with sh a c­
kle bracket and in stallation at front bracket is
shown in figure 7. A ll sh ack les and shackle pins
a r e d rilled and equipped with lubrication fittin gs.
Radius rods a re mounted on rubber bushings and
require no lubrication.
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL SUPPLEMENT