Throwout bearing, and Pilot bearing
12-01-2007, 01:16 PM
#4
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I've had both go bad in different set-ups. They both make a high-pitched and intermittant squeal. The pilot that went out in my TA only squealed when I shifted. The throw-out bearing that went out in my old Chevelle squealed all of the time and stopped when I shifted. If you have to go in there, might as well just do them both to be sure.
12-01-2007, 06:09 PM
#5
From this site http://www.carcare.org/Manual_Transm..._bearing.shtml
Pilot bearing
Description: The pilot bearing sits in a hole at the end of the engine�s crankshaft. Pilot bearings have three different designs: 1) roller bearing, 2) needle bearing, and 3) bronze bushing, which is actually more of bronze sleeve than a bearing. The bronze bushing and needle bearing are most common.
Purpose: The main purpose of the pilot bearing is to provide a low-friction support for the end of the transmission�s input shaft.
Maintenance Tips/Suggestions: The pilot bearing does not require routine maintenance, but should be replaced when clutch replacement becomes necessary. In some cases, pilot bearings can wear excessively when transmission-mounting bolts loosen. When this happens, the transmission�s input shaft moves around excessively and puts abnormal strain on the pilot bearing. If you suspect a problem with the pilot bearing or clutch, have it looked at immediately by a qualified technician. Putting it off will only make the problem worse.
Throw out bearing
Description: The throw-out bearing, or clutch release bearing as it's sometimes called, is located between the clutch fork and the pressure plate fingers. The throw-out bearing only operates when the clutch pedal is depressed; the bearing is not designed for continuous use.
Purpose: When the driver steps on the clutch pedal, the throw-out bearing applies force to the fingers of the spinning pressure plate to release the clutch. When the clutch pedal is released, the bearing sits idle and does not contact the pressure plate fingers.
Maintenance Tips/Suggestions: The classic symptom of a worn throw-out bearing is a whirring or growling sound when applying the clutch pedal, which goes away when releasing the pedal. Premature wear of the throw-out bearing can occur when there is insufficient clutch play, resulting in a throw-out bearing that spins continuously. If the bearing fails, it may seize and quickly wear the fingers of the pressure plate. The throw-out bearing does not require routine maintenance, but should be replaced when clutch replacement becomes necessary. Consult a professional technician to determine whether the throw-out bearing or other parts of the clutch assembly need replacement.
Pilot bearing
Description: The pilot bearing sits in a hole at the end of the engine�s crankshaft. Pilot bearings have three different designs: 1) roller bearing, 2) needle bearing, and 3) bronze bushing, which is actually more of bronze sleeve than a bearing. The bronze bushing and needle bearing are most common.
Purpose: The main purpose of the pilot bearing is to provide a low-friction support for the end of the transmission�s input shaft.
Maintenance Tips/Suggestions: The pilot bearing does not require routine maintenance, but should be replaced when clutch replacement becomes necessary. In some cases, pilot bearings can wear excessively when transmission-mounting bolts loosen. When this happens, the transmission�s input shaft moves around excessively and puts abnormal strain on the pilot bearing. If you suspect a problem with the pilot bearing or clutch, have it looked at immediately by a qualified technician. Putting it off will only make the problem worse.
Throw out bearing
Description: The throw-out bearing, or clutch release bearing as it's sometimes called, is located between the clutch fork and the pressure plate fingers. The throw-out bearing only operates when the clutch pedal is depressed; the bearing is not designed for continuous use.
Purpose: When the driver steps on the clutch pedal, the throw-out bearing applies force to the fingers of the spinning pressure plate to release the clutch. When the clutch pedal is released, the bearing sits idle and does not contact the pressure plate fingers.
Maintenance Tips/Suggestions: The classic symptom of a worn throw-out bearing is a whirring or growling sound when applying the clutch pedal, which goes away when releasing the pedal. Premature wear of the throw-out bearing can occur when there is insufficient clutch play, resulting in a throw-out bearing that spins continuously. If the bearing fails, it may seize and quickly wear the fingers of the pressure plate. The throw-out bearing does not require routine maintenance, but should be replaced when clutch replacement becomes necessary. Consult a professional technician to determine whether the throw-out bearing or other parts of the clutch assembly need replacement.
