GMC 4000 Series Service Manual page 465

Sec. 7D
Page 454
CLUTCH CONTROLS
1 Bleeder Valve
2 Fluid Entry Port
3 Cylinder Body
4 Push Rod Boot
Figure 14— Clutch Slave Cylinder
MASTER CYLINDER REPLACEMENT
Instructions for replacing
cylinders are the same as for brake master cylin­
ders as described in " HYDRAULIC BRAKES"
(SEC. 5C).
After installing clutch
bleed system and adjust push rod as described
previously under " Bleeding Hydraulic System"
and " Master Cylinder
Adjustment."
1 Clutch R elease Fork
2 Wedge
3 Adjustment Nut
4 Slave Cylinder Push
Rod
5 Push Rod Boot
6 Slave Cylinder 10 Adjustment Nut
A ssem bly
Figure 1 5 — Clutch Slave Cylinder Installed ITypical)
G M C S E R V I C E M A N U A L
5 Push Rod
6 Piston Retaining Ring
7 Piston
8 Piston Seals .'
t o o s
clutch master
master cylinder,
Push Rod Check and
7 Hydraulic Line From
M aster Cylinder
8 Slave Cylinder
Bleeder Valve
9 R elease Fork
Return Spring
Lock Nut
T-3087
CLUTCH SLAVE CYLINDER
The clutch slave cylinder (fig. 14) mounted
at side of clutch assembly (fig. 15) activates the
mechanical clutch release fork to disengage clutch
when cylinder is pressurized.
REMOVAL (Refer to Fig. 15)
1. Remove return spring from clutch release
fork.
2. Disconnect fluid line at slave cylinder.
3. Remove bolts retaining slave cylinder,
then remove cylinder assem bly and mounting
spacers (if used).
DISASSEMBLY (Refer to Fig. 14)
1. Remove cylinder push rod (5) and push rod
boot (4) from cylinder.
2. Remove piston retaining ring (6) from
slave cylinder.
CAUTION: Use extreme care while remov­
ing retaining ring to prevent damage to the bore
of the cylinder body (3).
3. Remove piston assembly (7) with seals (8)
from cylinder body (3).
NOTE: Piston can be jarred from body or
sm all amount of air pressure at line fitting will
force piston from bore. Use caution to prevent
damage to the piston.
4. If seals are found in good shape, they need
not be removed.
INSPECTION (Refer to Fig. 14)
1. Inspect slave cylinder bore, making sure
that it is smooth. A scored or damaged cylinder
body (3) must be replaced.
NOTE: Burrs at the bore side of inlet port
can be removed by honing or by use of crocus
cloth.
2. Check piston seals
Swelling of seals could be due to use of improper
brake fluid.
3. Check fit of the piston in the cylinder bore,
using a feeler gauge. This clearance should be
from 0.002" to 0.004".
ASSEMBLY (Refer to Fig. 14)
1. Install seals (8) into grooves of piston
(7) with lips of seals positioned to fluid end of
piston.
2. Dip piston and seals into clean brake fluid
then carefully install piston assembly into bore
of cylinder. Refer to figure 14 for proper position
of piston in cylinder.
3. Install retaining ring (6) into groove at
open end of cylinder.
4. Install boot (4) over push rod (5) and in­
stall rod and boot to slave cylinder.
(8) if removed.