Check the driven disc damper springs and the condition of the splines on the driven disc hub. When oiling the friction linings, replace the driven disk.
Check the condition of the friction linings. Measure the distance from the working surfaces of the pads to the heads of the rivets, if the size is less than 0.3 mm, the disk must be replaced.
Check the runout of the working surfaces of the friction linings. Put the driven disk on the mandrel or on the drive shaft of the gearbox, install it in the measuring centers and fix the indicator so that its tip rests on the outer side of the working surface of the lining (see fig. 160). Slowly turn the driven disk and read the indicator readings. If the runout exceeds 0.5 mm, the disc can be carefully straightened with forceps. In case of other malfunctions, the disk must be replaced.
Pic. 160. Measurement of the runout of the clutch disc.
Check the spline connection of the clutch disc and the gearbox input shaft. Put the driven disk on the splines of the shaft and, taking the outer edge of the disk with your thumb and forefinger, shake the disk in two directions. The gap should not exceed 0.4 mm. The reason for the increased clearance is usually the wear of the splines on the bushing of the driven disk. When replacing a disk, it is obligatory when buying an indicator for which engine the disk is intended.
Check the inner ends of the diaphragm spring for wear. In case of deep development, it is necessary to replace the clutch assembly.
The spread in height of the ends of the diaphragm spring should not exceed 0.5 mm. Straightening is allowed by bending the individual ends of the spring. If the bearing surfaces of the spring are worn more than 0.3 mm, the clutch must be replaced.
Check the flatness of the working surface of the pressure plate, as shown in fig. 161, use a feeler gauge to determine the gap. If the gap is more than 0.3 mm, the clutch must be replaced.
Pic. 161. Checking the wear of the working surface of the clutch pressure plate.