Hummer H3. Manual — part 927

Fig. 33: View Of Clutch Disc
Courtesy of GENERAL MOTORS CORP.

The clutch disc or driven member, is a critical component in the service life of the clutch system.
The disc provides smooth engagement and dampens engine vibrations. Mounted to the
transmission input shaft, between the flywheel and the clutch pressure plate, the disc slides on the
input shaft forward and backward. The disc is splined to the input shaft and cannot rotate without
rotating the input shaft. The critical parts of the clutch disc are the hub flange (3) and the torsion
springs (2). The hub flange (3) is located between the cover plate (4) and a retainer plate (6) and
splined to fit the input shaft. The torsion springs (2), in the dampener assembly, smooth the
engagement and dampen vibrations. Friction material (1) is riveted to numerous components,
called marcels or cushion segments (5). Waves in marcels soften engagement.

2007 Hummer H3

2007 TRANSMISSION Clutch - H3

Fig. 34: Locating Flywheel Weights (Manual Transmission)
Courtesy of GENERAL MOTORS CORP.

Bolted to the end of the crankshaft, the flywheel provides the mounting surface for the clutch.
During engagement, the disc is clamped against the flywheel by the pressure plate. The flywheel
acts as a heat sink, dissipating heat and moving it away from the clutch pressure plate and disc

2007 Hummer H3

2007 TRANSMISSION Clutch - H3

friction material. The flywheel must provide a smooth, flat surface in order for the clutch to
operate properly.

Fig. 35: View Of Pilot Bearing/Bushing
Courtesy of GENERAL MOTORS CORP.

A pilot bearing or bushing, is located in the end of the crankshaft. The pilot bearing supports the
end of the input shaft and centers the disc on the flywheel. The pilot bearing is a sintered bronze
bushing. A small and relatively inexpensive component, the pilot bearing or bushing should
always be replaced during clutch installation. The variety of conditions caused by a worn or
defective bearing or bushing is not worth the risk of having to remove the bell housing and
transmission to replace this small part.

2007 Hummer H3

2007 TRANSMISSION Clutch - H3

Fig. 36: View Of Clutch Pedal Reserve
Courtesy of GENERAL MOTORS CORP.

In order for the clutch to be completely disengaged and allow proper shifting of the transmission,
clutch pedal reserve is required. Clutch pedal reserve is the movement of the pedal from the down
stop or the floor (1), to where the clutch begins transmitting torque (2); it should be a minimum

2007 Hummer H3

2007 TRANSMISSION Clutch - H3