Assignment One

The clutch lets the driver control power flow between the engine and the transmission or transaxle. One- to disconnect the engine from the transmission/transaxle to permit the engine to remain running when the vehicle is stopped and to permit the transmission/transaxle to be shifted. Two –to connect and transmit engine torque to the transmission/transaxle. Three- to damper and absorb engine impulses and drive train vibration. Four- to provide a smooth engagement and disengagement between the engine and the transmission/transaxle.

Consists of a clutch disc, throwout bearing(release bearing), pressure plate spring(s), flywheel , and pressure plate, pilot bearing (or bushing), input shaft of the transmission/transaxle, front bearing retainer(also called the quill).

Summarize: When the clutch pedal is up, the clutch is engaged. When the clutch pedal is down, the clutch is disengaged.

A hydraulic clutch linkage, is made of a master cylinder and a slave cylinder. The other parts are throwout(release) bearing, clutch cover, bleeder valve, clutch fork, flexible hose, and clutch pedal. Movement of the clutch pedal creates hydraulic pressure in the master cylinder, which actuates the slave cylinder. The slave cylinder then moves the clutch fork. Levers and rods to transfer motion from the clutch pedal to the clutch fork. Its performed by, pushing the pedal down, a pushrod shoves on the bell crank and the bell crank reverses the forward movement of the clutch pedal. The other end of the bell crank is connected to the release rod. The release rod transfers bell crank movement to the clutch fork. It also provides a method of adjustment for the clutch. Cable operation is uses a steel cable inside a flexible housing to transfer pedal movement to the clutch fork.

Is made up of a circular metal plate attached to a reinforced, splined hub. Friction material is riveted to both sides of the clutch disc-one side touches the flywheel of the engine and the other side touches the friction surface of the pressure plate. The clutch facings are made of molded or woven asbestos riveted or bonded to the clutch disc. Woven materials are softer and help cushion clutch engagement, but they may not last as long as molded material. The thickness of the disc assembly must be uniform and its friction facings must be smooth, although not necessarily flat and true. The facing or disc, or both, are purposely warped to encourage “soft” engagement. Clutch friction material may contain paper, cotton, and bits of copper or brass wire with resin holding the mixture together. And is clamped between the engine flywheel and the pressure plate

Diaphragm spring style is the most commonly used, one large, round, spring-steel spring is used to apply even force on the clutch disc. These tend to be smaller assemblies, weight less, and have fewer parts then the coil spring assemblies. The one-piece diaphragm spring does the job of all the release levers and coil springs in a coil spring clutch. The spring is bent or dished and has pie-shaped segments running from the outer edge to the center. Its mounted in the pressure plate with the outer edge touching the back of the pressure plate face. The outer rim of the diaphragm is secured to the pressure plate and is pivoted on rings (pivot rings) approximately 1 inch from the outer edge

The pressure plate, like the flywheel, is usually made of nodular cast iron. A smooth, machined area on one side forms the friction disc contact surface. Its round, metallic devices containing springs and fingers, or levers, and controlled by the release fork connected to the shifter. It bolts to and revolves with the flywheel. It is spring-loaded device that can either engage or disengage the clutch disc and the flywheel.

Smooth out or dampens engine power pulses. Absorbs some of the heat created by clutch operation. Provides the connection point for the starter motor to crank the engine. Provides the application surface for the clutch friction disc.

High-performance vehicle and vehicles equipped with diesel engines use them. It’s used to dampen engine vibrations and keep them from being transmitted to the passenger compartment through the transmission and shift linkage. Consist of two separate flywheels attached with damper springs, friction material, and ball bearings to allow some movement between the primary and secondary flywheel. Uses fluid or lubricant, typically silicone-based, which helps absorb vibration and transmit torque. The two flywheels twist out of phase with each other by up to about 60 degrees to absorb torsional oscillations.

Depending on the length of the input shaft, it may also need a pilot bearing or bushing to support it at the engine end. On a rear-wheel-drive vehicle with a flat flywheel, have a much longer transmission input shaft. The pilot bearing or bushings, which is pressed into this bore, supports the engine end of the input shaft and provides a low friction surface for the shaft to ride on. Which will allow the shaft and friction disc perfectly aligned with the flywheel and pressure plate. Pilot bearing and bushings rotates with the crankshaft when the engine is running, that allows lower friction between these two moving parts. Pilot bushings are usually sintered metal sleeve pressed into the bore in the crankshaft flange. Not used on front wheel drive vehicles with a stepped flywheel, compact clutch assembly.

Can also be called throw out release bearing or clutch release bearing. Is used to disengage the clutch by depressing a lever or spring, which removes the clamping force from the clutch disc. Is a collar assembly, which reduces friction between the pressure plate levers and the release fork. It’s where the fixed, stationary clutch operating system meets the rapidly spinning clutch assembly.

One complaint could be while shifting into higher gears, (clutch is engaged) the engine speed seems to either rise or not drop (clutch is slipping). Another clutch problem could be the transmission is difficult (or impossible) to shift into reverse or just to shift in general. Or the transmission will be difficult (or impossible) to shift into gears.

1. Hoist the vehicle safely and remove the driveshaft. 2. Disconnect the shift linkage, speedometer connections, and reverse light switch connection. 3. Support the transmission with a transmission jack and then remove the rear cross member and bell housing bolts. 4. Carefully move the transmission toward the rear. Make sure to level transmission to avoid causing damage to the pilot bearing or clutch components. To take the input shaft out to slide it over the spline of the clutch disc a little wiggle can help accomplish that task. 5. U can the lower the transmission but make sure u clear the clutch before lowering it, inspect before being reinstalled after the clutch assembly has been replaced. 6. Mark the pressure plate and flywheel if they are to be reused to be reinstalled in the same location to maintain assembly balance. 7. Remove the clutch pressure plate retaining bolts, and remove the clutch assembly including the release bearing, pressure plate, and clutch disc. 8. Clean and inspect the flywheel. 9. Replace and or lightly lubricate the pilot bearing/bushing. 10. Install the clutch disc and pressure plate using an aligning tool to center the clutch disc and then torque the pressure plate bolt s to factory specifications. 11. Inspect the clutch release lever and replace if necessary. 12. Attach the replacement release bearing and install the transmission and torque the retaining bolts to factory specifications. 13. Reconnect the clutch linkage and place the transmission into high gear and have someone depress the clutch pedal. U should be able to grasp the output shaft and be able to turn it with your hand. A little side note; the transmission output shaft should be easy to rotate however this can only happen if the clutch is fully disengaged with the clutch pedal held down. In addition, if the output shaft is difficult to rotate then u may want to check the clutch linkage and clutch is correctly assembled. 14. Reinstall the rear cross member and torque the retaining bolts to factory specification. 15. Reconnect the shift linkage, speedometer, and reverse light connections. 16. Install the driveshaft and torque the u-joint retaining fastener to factory specifications. 17. Lower the vehicle and test-drive it to verify correct clutch operation.

One style of clutch linkage is adjusted by simply pulling upward on the clutch pedal until it stops. Some cable-operated clutch linkage is adjusted either at the bulkhead (firewall) where the cable exits the passenger compartment. Levers and rods have to be adjusted at the release rod going to the release fork; the release rod is threaded so it can be increased to raise the clutch pedal, or shortened to lower the clutch pedal. All u have to do is loosen the release rod nuts on the threaded rod until you have reached the desired free pedal travel. A clutch cable adjustment may be required for the sole purpose to maintain the correct pedal height and free travel. The clutch cable will have an adjusting nut. So all u have to do is turn it, to increase clutch pedal free travel, turn the clutch cable housing nut to shorten the housing, and, to decrease clutch pedal free travel, turn the nut to lengthen the housing. Hydraulic clutch is self adjusting, but usually doesn’t need to be adjusted. The hydraulically operated clutch is adjusted by changing the length of the slave cylinder pushrod. To adjust a hydraulic clutch, simply turn the nut or nuts on the pushrod as needed.

Fill the master cylinder with DOT 3 brake fluid and open the bleeder valve at the slave cylinder. Gravity should force the brake fluid to flow downward, expelling any trapped air that may be in the system. When brake fluid starts to drip from the bleeder valve, close the bleeder valve and check the clutch for normal operation. Another alternative is called manual bleeding and should be repeated as necessary until the normal operation of the clutch returns. It’s done by depressing the clutch pedal slowly as an assistant opens the bleeder valve at the slave cylinder that will force any trapped air out of the system.