Car clutch parts

How to detect clutch malfunction

The clutch is diagnosed in two stages. For the start, the system is tested with the engine off. Repeatedly push the pedal, check its travel smoothness, and listen to the sound. Extraneous sounds, such as squeaks and knocks, indicate failure. In the same stage, measure the working travel of the pedal. The optimal value should be 130 to 150 mm, depending on the model of the vehicle. Exact values are available in the technical documentation to the vehicle.

The next stage of diagnostics is performed with the engine idling. First, engage the reverse gear and listen. Abnormal sounds like crunching and crackling are the evidence of damaged clutch driven plate or clutch pressure plate. If the reverse gear cannot be engaged, it means that components of the system are badly damaged or worn, and need repair.

Watch the mechanism operation when driving. You may notice that the clutch requires diagnostics by the following symptoms:

• strong vibration;
• jerks during operation;
• incomplete clutch engagement and disengagement;
• extraneous sounds.

The reasons of clutch malfunction

The main reason of premature mechanism wear is severe non-compliance with the vehicle operation rules, namely, sudden starts at high RPM or holding the foot on the clutch pedal while driving. Poor quality components or components that have been used longer than their service life become faulty most often.

Often clutch failure is caused by malfunctions in its operating mechanism. Mechanical clutch controls are prone to damages like cable breakage, jamming or stretching, as well as linkage damage. Hydraulic actuators are characterized by faults like clogging and leakage of the working fluid due to damaged sealing elements. Oiling of the clutch driven plate lining occurs due to excessive amount of oil on the input shaft of the transmission or on the crankshaft bearing, as well as due to damaged oil seals in the engine and transmission.

Also, serviceability of the clutch is affected by the quality of maintenance and observance of its schedule. Incorrect adjustment of individual components of the system often has serious consequences, up to the loss of control over the vehicle.

Repairing and replacing the clutch

The component should be repaired and replaced at a service station. Clutch replacement involves the following:

1. dismantle the gearbox;
2. insert the aligner into the hole in the driven clutch plate hub;
3. take off the cover, the pressure plate and the driven plate;
4. check absence of cracks on the driven plate;
5. inspect the friction lining (if the heads of the rivets are sunk into the lining surface by less than 0.2 cm, the driven plate is to be replaced);
6. check the driven plate run-out (it should not exceed 0.5 mm, and no warping should be detected);
7. check the state of the flywheel and the pressure plate (replace if necessary);
8. replace the cover and plate if riveted joints between the parts are loosened or the seat rings of the clutch pressure spring are damaged;
9. before replacing the component, check the driven plate free movement along the gearbox input shaft splines (if the movement is impeded, the component is to be replaced or repaired);
10. install the aligner into the splines of the plate;
11. install the clutch onto the flywheel by the 3 centering pins, and fasten the component in place.