GMC 4000 Series Service Manual page 205

Sec. 5A
Page 198
HYDRAULIC BRAKES
1
2 Brake Lining
3 Brake Shoe
4 Hole Cover
5 Starwheel Crank
6 Adjuster Spring
7 Starwheel
8 Bolt
9 Spring Washer
CLEANING AND INSPECTION
1. Clean all dirt out of brake drum. Inspect
drum for roughness, scoring, or out-of-round.
Recondition or replace drum as necessary. Refer
to "Brake Drums" in this section.
2. Clean all dirt out of anchor pin holes and
adjusting screw openings in anchor supports.
3. Inspect wheel bearings and oil seals as
directed in "REAR HUBS AND BEARINGS" (SEC.
4C) of this manual.
4. Inspect brake shoe return springs. If they
are broken, cracked, or weakened, replace with
new springs.
5. Inspect threads on adjusting screw s and
in adjusting wheels for wear or damage. Replace
as necessary.
6. Check all automatic adjuster components
and replace any which are worn or damaged. Re­
place springs if broken, cracked, or weakened.
7. Check wheel cylinders as instructed under
"Wheel Cylinder Repair" in this section. Replace
with new cylinders if necessary.
G M C S E R V I C E M A N U A L
11 Bleeder Valve
12 Wheel Cylinder Cover
13 Wheel Cylinder
14 Anchor Pin
15 Shoe Return Spring (Short)
16 Adjuster Crank
17 C-washer
18 Hold-down Washer
Figure 4 4 — Type "FR-3A" Rear Brake Components
ings should be replaced if worn down close to rivet
heads. Refer to "Brake Shoe Relining" in this
section.
BRAKE SHOE INSTALLATION
and thread in star wheel screw from the shoe side,
friction ring end toward the shoe. For new linings,
back off screw s, taking care to not jam star wheels.
SCREWS.
away portion of web) located in the adjuster slot
and the "heel" in the anchor pin slot of anchor sup­
ports.
down washer and hold-down nut. Tighten nut finger-
tight and then back off nut one turn and insert nut
lock wire.
20 Lock Wire
21 Shoe Return Spring (Long)
22 Crank Link (Long)
23 Starwheel Screw
24 Hold-down Bolt
25 Crank Link (Short)
26 Eccentric Screw
27 Eccentric
8. Examine brake shoe linings for wear. Lin­
1. Insert star wheels in anchor support slots
NOTE: DO NOT LUBRICATE STAR WHEEL
2. Position one brake shoe with its "toe" (cut­
3. Install brake shoe hold-down bolt, hold-
- 4 5 8 0
t