While nothing can substitute perfectly for a careful examination and experience, it is nevertheless helpful to be aware of the symptoms which may accompany clutch problems so that they may be attacked in an orderly fashion. Some of these symptoms are:
For each of these symptoms, there is a logical sequence of possible causes and remedies. Once the causes are known, the remedies should be relatively obvious. It is for this reason that in the troubleshooting portion of this guide only the causes are discussed in any detail.EXCESSIVE CLUTCH NOISE
When the engine is idling and the foot is resting on the clutch pedal, there will be a high-pitched rubbing noise. Usual causes of release bearing failure are age of bearing, riding the clutch, insufficient pedal free-play, lack of lubricant in the bearing, and worn or out-of-true clutch release fingers.PILOT BEARING
Clutch shaft pilot bearing noises are heard only when the bearing is in operation; in other words, when the crankshaft speed is different from the speed of the clutch shaft-when the clutch is disengaged and the transmission is in gear. The noise made by the pilot bearing is a high-pitched squeal and the bearing, which is probably dry, should be replaced.TRANSMISSION PINION SHAFT BEARING
A rough or damaged input shaft bearing noise will be heard only when the clutch is engaged and the transmission is in any position. The noise is generally most noticeable when the transmission is in Neutral. The noise should diminish and completely disappear when the clutch is disengaged and the pinion gear of the transmission slows down and stops.TRANSMITTED ENGINE NOISES
When the correct amount of free-play is present in the clutch pedal, there should not be an unreasonable amount of noise transmitted to the passenger area via the clutch. Such noises, if they exist, are generally modified through a manipulation of the clutch pedal. Such problems rarely exist in the Volkswagen because of the relatively great distance between the clutch pedal and the engine compartment.CLUTCH LINKAGE NOISE
Noise in the clutch linkage is generally a clicking or snapping sound heard or felt in the pedal itself when the pedal is moved completely up or down. If the noise is heard to occur within the center tunnel of the passenger compartment, there is a strong possibility that lubrication is needed at the pivot point just inside the tunnel. In this case, the pedal cluster (throttle, brake and clutch) must be removed by means of the two mounting bolts, and the pivot point lubricated with a high quality grease such as lithium-base type. If such grease is not used to lubricate this point, it will be a matter of only a few weeks before lubrication is again required.CLUTCH CHATTER OR GRAB
The cause of clutch chatter or grab is generally located within the clutch assembly and can be corrected only by removal of the engine and the clutch from the vehicle. To diagnose, perform the following procedure:
- Check to ensure that the clutch linkage is in adjustment and not grinding. If necessary, the linkage should be adjusted, aligned and lubricated.
- Check for defective, worn, or loose engine and/or transmission mounts. If necessary, such mounts must be tightened or replaced.
- Check the attaching bolts on the clutch pressure plate for looseness. Also tighten or replace loose bolts on the transmission and clutch housings.
- Check freedom of movement of the clutch release bearing. Free it up or replace it as necessary.
- Check the clutch and flywheel for oil or grease. The trouble may also be caused by oil or grease on the friction disc or pressure plate.
- Check the friction disc for warpage, and ensure that the disc hub is not binding on the splines of the transmission input shaft.
- Check the disc and pressure plate for breakage.
- Examine the pressure plate and cover plate assembly for cracks or heat discoloration.
This condition is generally most noticeable when the car is started from a standing stop or when the gears are shifted quickly and the clutch disengaged quickly for fast acceleration. This treatment of the clutch may well be the cause of clutch slippage sooner or later, for no clutch is designed to withstand such mistreatment for long. One way of testing for clutch slippage is to apply the parking brake with the car on a level surface, start the engine and put the transmission into second gear. With the foot brake also applied, accelerate the engine slightly and release the clutch pedal. If the clutch is in good condition, it will grip and the engine will stall. If, however, the clutch is heard to slip, the cause may be one or more of the following:
In applying the clutch slippage test, it should be remembered that this test is most severe. In other words, one should not apply this test every other day in order to determine whether one's clutch is slipping. After not too many of these tests, it is practically guaranteed that the clutch will slip if it wasn't slipping before.CLUTCH DRAG OR FAILURE TO RELEASE
Clutch drag is the condition that takes place when the clutch pedal is fully depressed and the clutch disc is not completely released. The clutch disc does not come fully to rest, but continues to be rotated due to the rotation of the engine. Dragging of the clutch generally causes difficult shifting and clashing of the gears, especially when shifting in the lower gears. Possible causes of clutch drag are:
CLUTCH PEDAL PULSATION
This condition is evident when, with a slight pressure applied to the pedal, and the engine running, the pedal is felt to vibrate or pulsate with every revolution of the engine. When the pedal is pushed down further, the pulsation is no longer evident. Clutch pedal pulsation may be caused by any of the following:
LOW CLUTCH-FACING LIFE
When low clutch-facing life is experienced, the first thing to look for is the presence of improper driving habits on the part of the operator(s) of the vehicle. These are the most likely reasons why the lining is not lasting as long as it should. The possible causes of low clutch facing life are:
GEAR LOCK UP OR HARD SHIFTING
The causes of this condition are similar to those that cause the Clutch Drag or Failure to Release condition, and should be diagnosed in the same manner. If, however, the elimination of all possible causes as listed in this section does not serve to locate the cause of the problem, it is most likely that the problem lies in the shifting assembly, the transaxle cover, or in the transaxle itself. In the latter case, it will be necessary to dismantle the transaxle and correct the cause of the trouble.A HARD CLUTCH PEDAL
The presence of this condition is evidenced by a clutch pedal that requires an abnormal amount of pedal pressure in order to disengage the clutch. Possible causes are: