For 1990-2009 cars

## Clutch System Description and Operation SWBRHD

### Description and Operation - Up to 17 Sep 2007

#### Tremec 6-Speed

(1) | Clutch Pilot Bearing
(2) | Engine Flywheel
(3) | Clutch Driven Plate
(4) | Clutch Pressure Plate
(5) | Clutch Concentric Actuator Cylinder

#### Aisin AY6

(1) | Engine Flywheel
(2) | Clutch Driven Plate
(3) | Clutch Pressure Plate
(4) | Clutch Concentric Actuator Cylinder

The following are the principal components of the clutch system:

• | The driving members; attached to the engine and turning with the engine

• | The driven member; attached to the driveline and transmission and turning with the driveline and transmission

• | The operating members; including the spring, the clutch hydraulic system, and the clutch pedal linkages, required to apply and release the pressure, which holds the driving and driven members in contact with each other

### Clutch Driving Members

The clutch driving members consist of two, flat surface, iron plates. One of these surfaces is a heavy flat ring, with one side machined, known as the clutch driven plate and the other is the rear face of the engine flywheel. This is a dual mass flywheel that is designed to absorb engine vibrations before they are transmitted to the driveline, where they can create gear rattle. This is achieved by splitting the conventional flywheel into two sections: a primary section, which bolts to the crankshaft, and a secondary section, onto which the clutch is bolted. The primary section of the flywheel contains springs to isolate the engine vibrations. A small amount of fore aft looseness between the primary and secondary sections is normal. It is also normal for the secondary section to have a rotating travel of 25-50 mm (1-2 in) measured near the flywheel ring gear, while the primary section stays stationary.

### Clutch Driven Members (V6)

The driven member, clutch driven plate, has a splined hub that freely slides lengthwise along the splines of the transmission input shaft, which also drives the shaft through these same splines. Suitable friction facings are attached to each side of the plate by rivets.

In order to make the clutch engagement as smooth as possible and eliminate chatter; the steel segments driving the splined hub are slightly waved, which causes the contact pressure on the facings to rise gradually as the waved springs flatten out.

### Clutch Operating Members

The driving member and the driven member are held in contact by spring pressure. This pressure is exerted by a one-piece conical or diaphragm spring.

A diaphragm spring is a conical piece of spring steel that has been specially stamped to give it greater flexibility. The diaphragm is positioned between the cover and the pressure plate so that the diaphragm spring is nearly flat when the clutch is in the engaged position.

The pressure of the inner rim of the spring on the pressure plate decreases as the flat position is passed. The inner rim of the diaphragm bears on the pressure plate and is pivoted on a ring on the outer edge of the pressure plate. The application of a pulling load on the inner section of the pressure plate will cause the inner rim to move away from the flywheel and allow the pressure plate to move away from the clutch disc, thereby releasing or disengaging the clutch.

The clutch release bearing is moved by the actuator assembly to move the release levers which move the pressure plate to the rear, thus separating the clutch disc from the flywheel when the clutch pedal is depressed by the driver. A piston return spring in the actuator cylinder preloads the clutch linkage and assures a small load on the release bearing with the actuator assembly at all times. As the clutch disc wears, the diaphragm spring fingers move forward forcing the release bearing, actuator assembly, and pushrod to move. This movement forces the actuator cylinder piston to move forward in its bore, consuming hydraulic fluid from the master cylinder reservoir, thereby providing the SELF-ADJUSTING feature of the hydraulic clutch linkage system.

### Hydraulic Clutch Description

The clutch hydraulic system consists of a master cylinder and an actuator cylinder. When pressure is applied to the clutch pedal, pedal depressed, the pushrod contacts the plunger and pushes it down the bore of the master cylinder. In the first 0.8 mm (0.031 in) of movement, the recuperation seal closes the port to the fluid reservoir tank, and as the plunger continues to move down the bore of the cylinder, the fluid is forced through the outlet line to the actuator cylinder mounted to the driveline support assembly. As fluid is pushed down the pipe from the master cylinder, this in turn forces the piston in the actuator cylinder outward. As the actuator cylinder piston moves forward, it forces the release bearing to disengage the clutch pressure plate from the clutch disc. On the return stroke, pedal released, 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 opens the port to the fluid reservoir, allowing an unrestricted flow of fluid between system and reservoir. This systems has a clutch pedal hold down assist spring. Its purpose is to keep the clutch pedal depressed. This reduces driver fatigue during stop and go traffic.

### Description and Operation - After 17 Sept 2007

#### Tremec 6-Speed

(1) | Clutch Pilot Bearing
(2) | Engine Flywheel
(3) | Clutch Driven Plate
(4) | Clutch Pressure Plate
(5) | Clutch Actuator Cylinder

#### Aisin AY6

(1) | Engine Flywheel
(2) | Clutch Driven Plate
(3) | Clutch Pressure Plate
(4) | Clutch Actuator Cylinder

The following are the principal components of the clutch system:

• | The driving members; attached to the engine and turning with the engine.

• | The driven member; attached to the driveline and transmission and turning with the driveline and transmission.

• | The operating members; including the spring, the clutch hydraulic system, and the clutch pedal linkages, required to apply and release the pressure, which holds the driving and driven members in contact with each other.

### Clutch Driving Members

The clutch driving members consist of two, flat surface, iron plates. One of these surfaces is a heavy flat ring, with one side machined, known as the clutch driven plate and the other is the rear face of the engine flywheel. This is a dual mass flywheel that is designed to absorb engine vibrations before they are transmitted to the driveline, where they can create gear rattle. This is achieved by splitting the conventional flywheel into two sections: a primary section, which bolts to the crankshaft; and a secondary section, onto which the clutch is bolted. The primary section of the flywheel contains springs to isolate the engine vibrations. A small amount of fore aft looseness between the primary and secondary sections is normal. It is also normal for the secondary section to have a rotating travel of 25-50 mm (1-2 in) measured near the flywheel ring gear, while the primary section stays stationary.

### Clutch Driven Members (V6)

The driven member, clutch driven plate, has a splined hub that freely slides lengthwise along the splines of the transmission input shaft, which also drives the shaft through these same splines. Suitable friction facings are attached to each side of the plate by rivets.

In order to make the clutch engagement as smooth as possible and eliminate chatter; the steel segments driving the splined hub are slightly waved, which cause the contact pressure on the facings to rise gradually as the waved springs flatten out.

### Clutch Operating Members

The driving member and the driven member are held in contact by spring pressure. This pressure is exerted by a one-piece conical or diaphragm spring.

A diaphragm spring is a conical piece of spring steel that has been specially stamped to give it greater flexibility. The diaphragm is positioned between the cover and the pressure plate so that the diaphragm spring is nearly flat when the clutch is in the engaged position.

The pressure of the inner rim of the spring on the pressure plate decreases as the flat position is passed. The inner rim of the diaphragm bears on the pressure plate and is pivoted on a ring on the outer edge of the pressure plate. The application of a pulling load on the inner section of the pressure plate will cause the inner rim to move away from the flywheel and allow the pressure plate to move away from the clutch disc, thereby releasing or disengaging the clutch.

The clutch release bearing is moved by the actuator assembly to move the release levers which move the pressure plate to the rear, thus separating the clutch disc from the flywheel when the clutch pedal is depressed by the driver. A piston return spring in the actuator cylinder preloads the clutch linkage and assures a small load on the release bearing with the actuator assembly at all times. As the clutch disc wears, the diaphragm spring fingers move forward forcing the release bearing, actuator assembly, and pushrod to move. This movement forces the actuator cylinder piston to move forward in its bore, consuming hydraulic fluid from the master cylinder reservoir, thereby providing the SELF-ADJUSTING feature of the hydraulic clutch linkage system.

The electrical switch on the clutch pedal/bracket assembly has 3 functions. One function is a clutch interlock, ensuring the engine does not start unless the pedal is positioned on the floor. The second function is to cancel the cruise control system, if equipped, when the clutch pedal is depressed and the third function is to use the pedal position data to improve driveability.

### Hydraulic Clutch Description

The clutch hydraulic system consists of a master cylinder and an actuator cylinder. When pressure is applied to the clutch pedal, pedal depressed, the pushrod contacts the plunger and pushes it down the bore of the master cylinder. In the first 0.8 mm (0.031 in) of movement, the recuperation seal closes the port to the fluid reservoir tank, and as the plunger continues to move down the bore of the cylinder, the fluid is forced through the outlet line to the actuator cylinder mounted to the driveline support assembly. As fluid is pushed down the pipe from the master cylinder, this in turn forces the piston in the actuator cylinder outward. As the actuator cylinder piston moves forward, it forces the release bearing to disengage the clutch pressure plate from the clutch disc. On the return stroke, pedal released, 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 opens the port to the fluid reservoir, allowing an unrestricted flow of fluid between system and reservoir. This systems has a clutch pedal hold down assist spring. Its purpose is to keep the clutch pedal depressed. This reduces driver fatigue during stop and go traffic.