Pontiac Fiero 1988 Service Manual page 909

7C-2 HYDRAULIC CLUTCH
1 - CLUTCH HOUSING
(PART OF TRANSAXLE)
2 - INPUT SHAFT
3 - R E L E A S E BEARING
4 - COVER AND PRESSURE
PLATE ASM.
5 - DRIVEN DISC
6 - F L Y W H E E L
520017-7C
Figure 2 Clutch Cross Section
Operating Members
(Figure
4)
The clutch release system is operated by hydrau-
lic pressure and consists of the clutch pedal, clutch
master cylinder, clutch pipe and hose assembly,
clutch slave cylinder. Clutch fork lever, transmission
clutch shaft-and-fork assembly. The hydraulic clutch
system locates the clutch pedal and provides auto-
matic clutch adjustment. No adjustment of clutch
linkage or pedal position is required.
When pressure is applied to the clutch pedal to
release the clutch, hydraulic pressure is exerted
against the outer end of the clutch fork lever. As the
fork pivots on its shaft, the inner end pushes against
the release bearing. The bearing then pushes against
the diaphragm spring levers in the pressure plate
assembly, thereby releasing the clutch.
MASTER CYLINDER
(Figure 3)
The fluid reservoir tank is an integral part of the
cylinder. The operating principle is as follows:
When pressure is applied to the pedal, the push
rod contacts the plunger and pushes it up the bore of
the cylinder. In the first 1/32 in. of movement, the
center valve seal closes the port to the fluid tank and
as the plunger continues to move up the bore of the
cylinder, the fluid is forced through the outlet line to
the slave cylinder, mounted on the clutch housing.
On the return stroke, the plunger moves back as
a result of the return pressure of the clutch. Fluid
returns to the master cylinder and the final movement
of the plunger lifts the valve seal off the seat, allowing
an unrestricted flow of fluid between system and tank.
S L A V E CYLINDER
(Figure 6)
The cylinder is made with a threaded inlet port
which is connected to the master cylinder by a length
of pipe.
As fluid is pushed along the pipe from the mas-
ter cylinder to the slave cylinder, this in turn forces
the slave cylinder piston outward. A push rod con-
nects the slave cylinder and the clutch operating lever.
HYDRAULIC CLUTCH FLUID
CAUTION: Do not use mineral or
parafin base oils in the Clutch Hydraulic
System. These fluids will damage the
rubber parts in the cylinders.
FLUID
FLUID U N D E R P R E S S U R E
FLUID FLOW IN BOTH
D I R E C T I O N S
FLUID FLOW IN O N E
D I R E C T I O N
1 — O U T L E T
2 — V A L V E S E A L
3 — S P R I N G W A S H E R
4 — C E N T E R V A L V E
520021 7C
Figure 3 Master Cylinder Cross Section