Description; Hydraulic Clutch - GMC G Service Manual

7C-2 CLUTCH
CLUTCH
The principal components on a clutch are the driven
plate, pressure plate, diaphragm-type spring and a release
bearing.
The driven plate is splined on the transmission clutch
shaft so that it can move back and forth when the clutch is
disengaged, and can turn the shaft when the clutch is
engaged. The driven plate has friction pads riveted to both
sides and a flexible center with springs to absorb vibration.
The pressure plate has a machined surface that fits
against the driven plate and a diaphragm-type spring
mounted in a cover on the pressure plate. The spring holds
the pressure plate and driven plate together against the
engine flywheel when the clutch is engaged.
The release bearing is a ball-thrust bearing on a sleeve
that pushes in on the center of the diaphragm spring,
releasing pressure on the pressure plate and driven plate to
disengage the clutch.
Before repairing the clutch, check the transmission and
shift linkage, and the engine mounts to be sure the problem
is in the clutch.
LINKAGE
1. Check the clutch rods for bending and damage.
2. Check for worn swivels and loose or damaged mount­
ing brackets.
3. Check the clutch lever for bending, wear and
damage.
• E Je sure there is some clearance between the
clutch lever and the mounting brackets and ball
studs.
4. Lubricate the clutch linkage.
CLUTCH PEDAL
1. Check the bushings for dirt, wear, and damage.
2. Check the clutch release.
• Hold the clutch pedal 12.7 mm (1/2 in.) above
the floor mat with the engine running and the
parking brake on.

DESCRIPTION

HYDRAULIC CONTROLS — R/V MODELS
The hydraulic clutch has a master cylinder with a sepa­
rate reservoir. The clutch pedal moves the master cylinder
push rod and a secondary cylinder at the clutch housing
moves the clutch fork and the release bearing.
MECHANICAL CONTROLS — G- AND P-MODELS
G-models have a pull rod from the clutch pedal that
moves a cross lever. The cross lever moves the clutch fork
and the release bearing with an adjustable rod.
P-models have an upper pull rod from the clutch pedal to
a bell crank lever and a lower pull rod from the bell crank
lever to a cross lever. The cross lever moves the clutch fork
and the release bearing with an adjustable rod.
INSPECTION
1. Check the clutch fork for dirt, wear and damage.
2. Check the clutch fork for proper installation and
lubrication.
3. Check the release bearing and clearance between
the spring fingers and the transmission.
1. Check the hoses for cracks and wear
2. Check the cylinders for loose mounting screws and
signs of leakage.
3. Check the clutch pedal travel, it should be 210.8mm
(8.3 in).
4. Check the secondary pushrod travel at the clutch
fork, it should be at least 25.4mm (1.0 in).
5. Bleed the controls and repeat as needed.
CLUTCH CONTROLS
• Move the shift lever from first gear to reverse
gear and back several times.
• If the shift is smooth, the clutch is disengaging
fully.
• Adjust the clutch linkage and repeat, if needed.
RELEASE BEARING

HYDRAULIC CLUTCH