GMC 1989 Light Duty Truck Repair Manual page 326

BRAKES
5 - 8
24. Body
25. Spring
28. Secondary Piston
30. Primary Piston Assembly
31. Snap Ring
Figure 15— Cast Iron Master Cylinder
Components
A stained or discolored cylinder bore with crocus
cloth.
Inspect
L9
Diaphragm for cuts, cracks, or a swollen condition.
Cylinder bore for scoring or corrosion. If corrosion is
present, replace the cylinder. Do not attempt to hone
the bore.
+ «-
Install or C onnect (Figure 19)
• Lubricate all the seals and cylinder bore with clean
brake fluid.
1. Secondary spring (48).
2. Secondary piston assembly (49).
3. Piston return spring (50).
26. Spring Retainer
27. Primary Seal
28. Secondary Piston
29. Secondary Seals
Figure 16— S econ d ary Piston A ssem bly
4. Primary piston assembly (51) and snap ring (52).
• The prim ary piston m ust be depressed to
5. O-ring (55) and springs (47).
6
. Valve poppets (46) and com pensating valve seals
(45).
F-04397
• Depress and hold the prim ary piston assembly
7. Reservoir (44).
N O TIC E: See " N o tic e " on p a g e 5-1 o f this
section.
8 . Bolts (54).
• Bolts to 18 N-m (13 ft. lbs.).
9. Diaphragm (42) into the cover (41).
10. Cover (41).
F-04398
install the snap ring.
with a smooth rounded end tool.
T ighten
Figure 18— Installing Tube S eats