Chevrolet 70 1969 Series, Shop Manual

Page: 267 / 913

BRAKES 5C-74
SECTION 5C
PARKING BRAKES
EXTERNAL CONTRACTING BAND TYPE BRAKE
External contracting band type parking brake
is mounted at rear of transmission (fig. 1).
Brake drum is attached to the transmission
output shaft flange in conjunction with the propeller
shaft universal joint flange. The band and lining
assembly is supported around the drum by a bracket
on the adjustment side and an anchor bar on the
stationary side. Both supports are attached to the
transmission case. The band contracts around the
drum when brake is applied.
Linkage connecting parking brake lever to
brake operating cams varies on different models,
however, adjustment is made at brake assembly
in same manner.
BAND T Y P E A D J U S T M E N T (Fig. 1)
1. Place hand lever in fully released position.
Disconnect brake rod or cablefrom operating cams
by removing cotter pin and clevis pin.
2. Remove lock wire from anchor adjusting
screw and turn anchor screw as necessary to ob­
tain 0.010" to 0.015" between lining and drum.
Install lock wire in anchor screw.
3. Loosen lock nut on locating bolt and tighten
adjusting nut on locating bolt until there is a clear­
ance of 0.020" between lower end of lining and
drum. Measure clearance about 1-1/2 inch from
end of lining. When correct clearance is obtained,
tighten lock nut on locating bolt.
4. Loosen lock nut on adjusting bolt and tighten
adjusting nut on adjusting bolt to obtain clearance
of 0.020" between upper end of lining and drum.
Measure clearance about 1-1/2 inch from end of
lining. Tighten lock nut on adjusting bolt.
5. Adjust end on brake rod so that clevis pin
may be freely inserted through operating cams and
rod end. Install clevis pin and cotter pin, then
tighten lock nut on rod end.
BR AK E BAND R E M O V A L (Fig. 1)
1. Disconnect brake rod or cable from oper­
ating cams. Remove clevis pin and operating cams
from upper end of adjusting bolt.
2. Remove nuts, washers, and tension spring
from lower end of adjusting bolt. Lift adjusting
bolt straight up out of brake band brackets and
support, stripping release springs and cam shoe
from bolt as bolt is removed.
3. Remove nuts from locating bolt, then re­
move bolt.
4. Remove lock wire from anchor screw, then
back screw out until clear of anchor bar.
5. Slide band and lining assembly straight to
rear off brake drum and anchor bar (fig. 1), re­
moving band and lining assembly off over propeller
shaft.
INSPECTION
1. Examine braking surface of drumf or rough­
ness or scoring. If drum is worn or damaged, it
must be replaced.
2. Inspect brake lining. If worn down close to
rivet heads, new lining must be installed.
3. Examine tension and release springs; re­
place if weak or broken.
B R AK E BAND IN S T A L L A T IO N (Fig. 1)
1. Place band and lining assembly over pro­
peller shaft. Place anchor screw spring in depres­
sion of anchor bar, and compress spring as band
1 Brake Band 11
2 Cam s 12
3 Links 13
4 Clevis Pins 14
5 C a m Shoe 15
6 Lock Nut 16
7 Adjusting Nut 17
8 Locating Bolt 18
9 Tension Spring 19
10 Washer 20
Adjusting Nut
Lock Nut
Lock Washer
Brake Lining
Release Springs
Brake Drum
Adjusting Bolt
Anchor Bar
Anchor Screw
Lock Wire
_______ TPM-9873
Figure 1 — Contracting Band (External) Parking Brake (Typical)
CHEVROLET SERIES 70-80 HEAVY DUTY TRUCK SH O P MANUAL