Pontiac FIREBIRD 1972 Service Manual page 815

CLUTCH, MANUAL TRANSMISSIONS 7-3
I
Fig.
7-2
Cross Section of Typical Flat-Finger Clutch
Two variations of this design are the flat-finger type (Fig.
7-2) and the bent-finger type (Fig. 7-3). These diaphragm
spring clutches feature rate decreasing pedal effort, which
eliminates the need of an over-center spring assist. Pres-
sure plate spring pressure forces the driven plate against
the flywheel, thereby coupling the engine to the transmis-
sion.
The clutch release'mechanism consists of a ball thrust
bearing, appropriate levers and linkage to manually con-
trol the action of the bearing. The ball thrust bearing
(clutch release bearing) is piloted on a tubular support
which is concentric with and enclosing the transmission
main drive (clutch) gear. When pressure is applied to the
clutch pedal to release the clutch, the clutch fork pivots
on its ball socket. The inner end of the fork then pushes
the release bearing forward so that it presses against the
(Fig. 7-1). Pedal effort is transmitted by the pedal through
the countershaft and lever assembly to the clutch fork.
Several clutches are being used, depending on the engine
option. The clutches differ in diaphragm spring design,
damper spring calibration and driven disc diameter.
Clutch usages are shown in Fig. 7-4.
A clutch safety switch is standard on all models with
manual transmission. Designed to prevent cranking "in
gear", this switch will not permit the starter to operate
unless the clutch pedal is depressed far enough to com-
pletely disengage the clutch.
While the steering column lock requires that manual
transmission be in "Reverse" gear before removing the
ignition key, the clutch safety switch prevents engine
cranking "in gear" when the steering column is unlocked
inner ends of the clutch release levers, releasing the clutch while starting.
Fig. 7-3 Cross Section of Typical Bent-Finger Clutch