6.6L Clutch

The 6.6L clutch system is described as the following:

• Size - 302 mm (12 in)
• Clutch pressure plate - Diaphragm spring plate, self adjusting
• Clutch disc - No damper spring style
• Hydraulic system - 6 speed

Fig 1: 5 Speed Transmission Hydraulic Clutch System

Courtesy of GENERAL MOTORS CORP.

The reservoir, which is part of the master cylinder, supplies the fluid at the front of the master cylinder through the center feed port (1). The center feed ports allow the flow of fluid from the reservoir to the cylinder when the pedal is in the complete returned position. The master cylinder uses a spring (3) to return the piston (2) to the clutch engagement position. A bleeder screw (4) is located at the clutch actuator cylinder for bleeding the hydraulic system.

Fig 2: 6 Speed Transmission Hydraulic Clutch System

Courtesy of GENERAL MOTORS CORP.

The reservoir, mounted on the front of the master cylinder, supplies low pressure (3) fluid to the master cylinder by a hose to the rear of the master cylinder, through a compensation port (1). The compensation port (1), a small groove in the nylon bore of the master cylinder, is closed from the high pressure (4) fluid by the seals on the piston (2) after the clutch pedal is depressed 8 mm (0.31 in). When the clutch pedal is in the full upright position, the port is opened to allow air to return to the reservoir, or to allow fluid from the reservoir to fill the cylinder bore. The piston in the master cylinder is connected to the pedal pushrod. The clutch pedal has a spring for returning the piston to the clutch engagement position. The system is bled by pumping the pedal, self-bleeding, or by the vacuum pump method on the reservoir.

Fig 3: Clutch Pedal Reserve

Courtesy of GENERAL MOTORS CORP.

Clutch pedal reserve is necessary in order for the clutch to be completely disengaged and allow proper shifting of the transmission. Clutch pedal reserve is the movement of the pedal after the clutch has fully released. The distance from clutch full release (2) to pedal fully down (1) is the clutch reserve dimension, typically 25-38 mm (1.0-1.5 in).

In order to test to determine if the clutch is properly releasing, and the hydraulic system is functioning properly:

1. Depress the clutch pedal fully to disengage the clutch.
2. Shift into a low gear, either 1st or reverse.
3. Slowly shift out of the gear, only to disengage the synchronizer sleeve from the speed gear engagement teeth.
4. Let up on the pedal, to engage the clutch.
5. Depress the clutch pedal and shift back into gear.

If the clutch is releasing properly, you should be able to engage the gear without grinding after 4 to 5 seconds, which is the time for the clutch disc to quit spinning.