Chevrolet 10 Series 1970, Service Manual

Page: 301 / 671

BRAKES 5-63
2. R eplace sam e number sp acers as rem oved and
in sta ll snap ring.
3. In stall brake shoes, snap rin gs, fla t hold down
w ashers and “ C ” w ash ers. C rim p “ C ” washers on
shoe guide studs.
4. In stall brake shoe return spring.
5. In stall cam r o lle r s . L u b ricate slots only.
6. Install w heel and brake drum assem bly, fron t wheel
bearin g, sp a cer and spindle nut. Tighten spindle nut
to 55 ft. lbs. torque and in s e rt c o tter pin. (T h e nut
m ay have to be backed o ff sligh tly to allow entrance
o f co tter pin.)
7. In stall rim and tir e assem bly, rim locks and wheel
nuts. Tighten nuts on opposite sid es altern a tely to
torque s p ecified in Section 3 under W heels and T ir e s .
NOTE: W heel nuts must be checked at the end
o f 500 m ile s to be certa in that rim locks and
nut have not loosened.
R ear
1. Make certain cam shaft is engaged p ro p e rly b efo re
in stallin g reta in er. Set brake shoes in place and
make certain pins and r o lle r s w ill engage p ro p er
location on cam . Do not in sta ll r o lle r s and pins at
this tim e. Install anchor pins, sp acer w ashers and
snap rings.
2. In stall brake shoe return springs.
3. P r y shoes apart and in sta ll brake shoe cam r o lle r s
and r o lle r pins. L u b ricate I.D. o f cam r o lle r s and
O.D. o f the r o lle r pins.
4. In stall r e a r wheel. In stall axle outer bearin g and
adjusting nut. Adjust bearin g as fo llo w s:
a. Tighten adjusting nut with T-handle wrench 12"
long each side, until wrench tight, at the same
tim e rotating hub to make sure a ll su rfaces are
in p ro p e r contact. Then loosen nut at lea st 45
d e g re e s , o r m ore i f n ecessa ry, until a lip o f the
nut lock w ill engage the n earest fla t on the nut.
b. Make sure wheel turns fr e e ly , then in sta ll nut
lock and locking nut. Tighten locking nut fir m ly .
Bend lip o f nut lock o v e r fla t o f locking nut.
c. A pply a rope o f smooth cup gre a s e around outer
bearing.
5. In stall axle shaft and secu re with “ sp lit w e d g e '’
locks and retaining nuts.
6. Install inner rim and tir e assem bly (make certa in
va lv e points toward the ou tside), rim sp a cer and
outer rim and tir e assem b ly making certa in tir e
va lv e is 180° away fro m inner tir e va lve.
7. Install rim locks and nuts. Tighten nuts a ltern ately
on opposite sides, to torque sp ecified in Section 3
under W heels and T ir e s .
NOTE: Nuts and rim locks must be torqued at
the end o f 100 m ile s , 500 m ile s , 1,000 m ile s and
e v e r y 1,000 m iles th e re a fte r to be certain they
have not loosened.
AIR BRAKE
Adjustm ent
The brake sh oe-to-dru m fre e p la y adjustment o f a ir
brakes is accom plished by means o f the slack adjuster
which is in corporated in the cam shaft le v e r .
With brakes relea sed , the angle fo rm e d by the push
rod and cam shaft le v e r must be g re a te r than 90° and
a ll units should be set at the same angle. With the brakes
applied, a fte r being adjusted, this angle should be ap ­
pro x im a tely 90°. The position of the push rod yoke on
the push rod should be adjusted i f n ecessary until these
conditions p re v a il. P ro p e r sh oe-to-d ru m freep la y may be
obtained by p erfo rm in g the follow in g procedu res:
Front and Rear
1. Using the p ro p er s iz e “ b ox” wrench o r deep socket
wrench, d epress the spring loaded c o lla r that locks
the slack adju ster adjusting nut in place (fig . 104).
2. Turn the adjusting nut until a uniform light drag is
fe lt on the w heels.
3. Back o ff on nut until wheel is just fr e e ; then back o ff
1/2 turn fo r facin g-to-d ru m running clearan ce. R e ­
peat this operation at a ll slack adjusters.
RESERVOIRS
A ir p ressu re r e s e r v o ir s are provid ed fo r the purpose
o f storin g a ir under p ressu re.
Drain cocks a re p rovided in the r e s e r v o ir s to drain o ff
condensed m oisture.
Removal
1. B leed a ll a ir out of brake system .
2. Disconnect a ir lin es and rem ove drain cock.
3. R em ove mounting bracket nuts and bolts and rem ove
re s e r v o ir .
Cleaning and Inspection
In m ost cases, m a jo r re p a irs on r e s e r v o ir s a re not
econ om ical o r p ra ctica l. If a r e s e r v o ir has been dam ­
aged so as to be unfit fo r s e rv ic e , always rep lace it with
a new one.
In exceptional cases w here the inside o f a r e s e r v o ir
has been coated with sludge that cannot be drained o ff it
can be rem oved with steam and hot w ater.
C A U TIO N : N e v e r plug up r e s e r v o ir and apply
steam as seriou s damage w ill resu lt. Under no
conditions should m ore than 150 psi (steam
p re s s u re ) be applied to r e s e r v o ir .
Testing
When testing fo r leakage, only w ater p ressu re should
be used. In this case only, higher than norm al p ressu res
may be exceeded but only fo r a m atter o f seconds.
Installation
1. Install r e s e r v o ir in p lace with mounting brack et nuts
and bolts. But do not tighten secu rely at this tim e.
2. Install drain cock and assem ble and s ecu rely tighten
a ll a ir p ressu re lin es.
3. Tighten r e s e r v o ir mounting bolts and nuts and make
certain r e s e r v o ir w ill not vib rate during s e r v ic e as
this w ill cause prem atu re p ressu re line fa ilu re .
DRAIN COCKS
The drain cock is a sim p le on -off va lve located on the
bottom o f the r e s e r v o ir .
Removal
Apply wrench to the hexagon portion o f the body only.
U nscrew and rem ove.
CHEVROLET TRUCK SERVICE MANUAL