4. Improper adjustment of the pressure plate release lever. (Some pressure plates require this adjustment before the part is installed.)
To correct clutch dragging, adjust the free travel. Make this adjustment according to the manufacturer's specifications. If the problem is not corrected with this adjustment, you may need to remove the clutch for repairs or replacement.
Because of heat generation, slipping of the clutch (while it is engaged) can severely damage the clutch disk facings. The contact surfaces on the pressure plate and the flywheel may also be damaged. If a clutch is allowed to continue to slip, complete clutch failure may result. Clutch slipping is most obvious when you are just starting out from a dead stop or upon sudden acceleration in a low gear. Slipping will be very noticeable in a vehicle with a heavy load.
Causes of clutch slippage include incorrect clutch pedal free travel, binding in the clutch linkage, and "riding the clutch." If the free travel is insufficient, there is a tendency for the release bearing to contact the release levers, even though the operator's foot is off the clutch pedal. As a result, the clutch disk may not be clamped tightly between the flywheel and the pressure plate. Readjustment of the pedal free travel will solve this problem. If you do not adjust the free travel at once, the release bearing, as well as the clutch disk, will wear rapidly.
If a binding condition exists in the clutch linkage, the pedal will be reluctant to return when it is released. So again, you may encounter clutch slippage. To solve this problem, "free up" the linkage that is binding by simply lubricating or aligning the clutch linkage. If this fails to correct the problem, you may have to remove the clutch for further inspection and repair.
"Riding the clutch" is an operator problem whereby the operator steadily drives with a foot on the clutch pedal. As a result, the pedal may be partially depressed and cause clutch slippage. If this form of operator abuse is suspected, contact the transportation supervisor. The problem should be corrected through proper operator training.
Occasionally, you may encounter a clutch that grabs or chatters, no matter how evenly or gradually you try to engage it. If the linkage operates satisfactorily and the engine and clutch mountings are not loose, you may have to remove the clutch assembly from the vehicle to cure the trouble. The probable causes are loose, glazed, oily, or greasy disk facings; binding of the disk on the clutch shaft; broken or otherwise defective pressure plate springs; or a broken or otherwise defective pressure plate.
A careful inspection of all clutch parts should reveal any defective items. In any case, replace any damaged parts and rebuild the clutch as specified by the manufacturer. In most cases, it is best that you install the clutch as a unit which includes replacing the clutch disk, pressure plate, release bearing, pilot bearing and resurfacing the flywheel. Replacing the complete assembly prevents the need for rework
A noisy clutch may be caused by a number of conditions. Most of these conditions can be corrected only after you have removed the assembly from the vehicle. Start your inspection by noting whether or not the noise occurs when the clutch is engaged or disengaged. Do this with the engine idling since the noise is likely to be most apparent at this time.
To begin with, when you have the clutch disengaged, you may discover that the noise coming from the clutch is due to lack of lubrication or to defects in the assembly. For instance, a dry or binding release bearing is likely to squeal when it is placed in operation. If it does, you will usually need to replace the bearing. On some vehicles, however, provisions are made for lubricating this bearing. If so, you can generally lubricate or replace the bearing without removing the clutch assembly. Still, you may need to remove the transmission and the lower cover from the flywheel housing to get to the bearing. However, it usually pays for you to go a little further and inspect the entire clutch assembly if you must remove the transmission for any reason.
Noise may also come from a worn or dry pilot bearing. Such a bearing tends to "whine" when it is out of grease. This noise usually occurs when the vehicle is stationary, with the engine running, the transmission in gear, and the clutch disengaged. To remedy this, replace the bearing and make sure it is properly lubricated if it is not a prepacked bearing.
Still other clutch noises may occur when you have the clutch disengaged. Any one of several conditions can be responsible for noisy operation. For example, the clutch disk may be loose on the transmission shaft (diskContinue Reading