To replace a worn-out clutch slave disk, you must first remove the gearbox - this work requires solid knowledge and the use of special tools and devices. Therefore, the clutch must be replaced in a car repair shop.
Basic elements of the clutch
Flywheel.
It is installed on the end of the crankshaft and bolted to it.
Clutch slave disc.
It moves freely on the splines of the primary shaft of the gearbox and is clamped between the flywheel and the pressure plate by the force created by the central diaphragm spring. Friction linings are riveted on both sides of the driven disk. The driven clutch disk is connected to the hub through parts of the torsional vibration damper. The need for a torsional vibration damper is caused by the following.
When the vehicle speed changes abruptly, when driving over uneven roads, when the clutch is engaged abruptly, and due to uneven engine operation, dynamic loads arise in the vehicle transmission, causing the transmission shafts to twist (untwist). Uneven engine torque can cause significant overloads in the transmission due to the occurrence of torsional vibrations and resonance when the frequencies of the transmitted loads coincide with the frequencies of the transmission's natural vibrations. Elastic vibrations of the transmission lead not only to noise in the mechanisms and units, but also to dangerous vibrations, and sometimes to breakdowns of parts when the vibration amplitude increases significantly. The energy of torsional vibrations is absorbed by a damper.
The outer diameter of the clutch disc of the Ford Fiesta is 180 mm (Fiesta 1.8D – 210 mm).
Clutch release bearing -
(built into the clutch slave cylinder on all Fiesta models since 1996). It acts on the pressure plate spring and moves the pressure plate away from the driven clutch disc. As a result, the clutch disc is released from its clamped position and can rotate freely between the flywheel and the pressure plate, as a result of which the engine and gearbox are disconnected.
Automatic gap adjustment.
Fig. 12.2. Hydraulic clutch drive: 1 – pre-pressure valve; 2 – brake fluid reservoir; 3 – liquid supply hose; 4 – clutch master cylinder; 5 – pressure pipeline; 6 – clutch slave cylinder, combined with clutch release bearing (on all Fiesta vehicles since 1996)
Since 1996, all Fiesta cars have automatically adjusted the required clearance of the clutch pedal. If the clutch in your car begins to slip, then it is necessary to replace the driven clutch disc or check the functionality of the pre-pressure valve of the hydraulic clutch drive (Fig. 12.2).
TECHNICAL DICTIONARY
Clutch operation
Clutch clearance.
Until the clutch pedal is pressed, the clutch release bearing is located at a certain distance from the diaphragm spring of the pressure plate. As the vehicle mileage increases, the clutch clearance, similar to the wear of the driven clutch disc, becomes smaller: the diaphragm spring approaches the clutch release bearing. As soon as the bearing touches the diaphragm spring without clearance, the pressing force of the pressure plate decreases, which automatically reduces the friction force between the surfaces of the driven clutch disc, flywheel and clutch pressure plate. If the clearance is not adjusted, the clutch no longer transmits torque from the engine to the gearbox without slipping - the clutch slips.
Disengaging the clutch.
When the clutch pedal is pressed, the piston moves in the clutch master cylinder and compresses the fluid, which flows through the hose into the clutch slave cylinder. Under pressure, the piston moves out of the clutch slave cylinder and moves the bearing, which acts on the spring of the pressure plate and moves the pressure plate away from the driven clutch disc. As a result, the clutch disc is released from the clamped position and can rotate freely between the flywheel and the pressure plate, as a result of which the engine and gearbox are disconnected.
Engaging the clutch.
When the clutch pedal is released, the diaphragm spring again presses the pressure plate against the flywheel, and all clutch components form a strong, force-locking connection - torque is transmitted from the engine to the gearbox.
(Information for this article was taken from the website: «fordbook»)