Clutch — General information and component condition check (Opel Astra G)

Design of the clutch and its drive components



All models equipped with a manual transmission use a single-plate dry clutch with a diaphragm spring. The hub of the friction (driven) disk is equipped with longitudinal splines that engage with the splines of the transmission primary shaft journal. The friction and pressure plates of the clutch are held in contact with each other by the force developed by the diaphragm spring of the pressure plate. The design of the clutch and its drive - see the illustration Design of the clutch and its drive components.

(Original posted on the website: opelbook.ru)

The clutch is released hydraulically. The release drive consists of a clutch pedal, a main hydraulic cylinder with a reservoir, connecting lines and a slave cylinder combined with a release bearing, mounted directly on the input shaft of the gearbox (see illustration Design of the clutch and its drive components).



When the pedal is depressed, the hydraulic pressure in the system tract increases, which is then applied to the release bearing mounted in the slave cylinder. The bearing, under the influence of hydraulic force, is pressed against the petals of the diaphragm spring of the pressure plate in the clutch basket. By bending, the spring interrupts the contact of the pressure and driven disks, releasing the latter.

When servicing a clutch, in addition to replacing components that are obviously damaged, it is necessary to perform some initial checks (it is assumed that the gearbox is in good condition):

• First of all, you should check the fluid level in the clutch master cylinder (see Chapter Routine maintenance). If necessary, make adjustments by adding the required amount of hydraulic fluid and carefully inspect the system for signs of leaks. When emptying the master cylinder reservoir, it is necessary to remove air locks from the hydraulic circuit (see Bleeding air from the hydraulic circuit of the clutch release drive), then check the proper functioning of the clutch.
• To estimate the clutch shift time, start the engine at normal idle speed. Make sure the transmission is in neutral and release the clutch pedal. Now depress the clutch pedal and wait a few seconds before engaging reverse gear. The shift should not produce any grinding or other abnormal noises, which would most likely indicate a faulty driven disc or clutch basket assembly.
• To check that the clutch is fully disengaged, apply the parking brake and start the engine. Keeping the clutch pedal about 13 mm above the floor, shift the gearbox between first and reverse gears. If there is any interference when shifting the lever, this indicates a faulty clutch release mechanism component. Check the stroke of the clutch slave cylinder pusher. When the pedal is fully depressed, the pusher should extend noticeably; otherwise, check the hydraulic fluid level in the master cylinder.
• Perform a visual inspection of the condition of the axle bushings at the top of the clutch pedal. Make sure there are no signs of jamming or excessive axle play.