Schaeffler Group USA Inc.
AUTOMOTIVE AFTERMARKET
Noise
Proper lubrication during clutch installation can reduce the chances of noise problems down the road.
Squeals and growls are usually caused by worn or seized bearings. Chirping noises are usually caused by vibration somewhere in the release system.
Determine the source of bearing noise by setting the parking brake, putting the vehicle in neutral and starting the engine. Refer to the chart below to determine the source of the noise.
| | NOISE | SOURCE | |
| Growling or grinding when the clutch is engaged. | Transmission input shaft bearing | ||
| Squealing when the pedal is actuated and held. | Pilot bearing or pilot bushing | ||
| Chirping that intensifies when the pedal is slowly actuated. | Release bearing | ||
| Chirping while idling in neutral that disappears when the pedal is slowly actuated. | Fork/pivot ball contact point | ||
| Causes of Noise | |
| External | Internal |
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The photographs below of damaged clutch system components represent common failures. Compare them with the products you remove from the vehicle to assist in your diagnosis. The damage you see may be more pronounced or more subtle than these examples.
Worn Splines
Related Symptom: Harsh engagement, chatter.
Cause: Worn pilot bearing, worn input shaft, misalignment between the engine and transmission.
Check for misalignment on high-mileage vehicles and those in which the engine or transmission was replaced.
Broken Cover Plate
Related Symptom: No release.
Cause: Driver abuse over-torquing the disc, lugging the engine, high RPM engagement, harsh downshifting, vehicle suspension or engine modifications.
Worn Grooves
Related Symptoms: Slipping, chatter.
Cause: Excessive bearing preload caused by riding the clutch, incorrect release system adjustment, defective hydraulic release system.
Broken Torsion Damper
Related Symptoms: Harsh engagement, no release.
Cause: High RPM engagement abusing the torsion damper and causing the springs to fracture and dislodge from the retainer plate.
A no-release condition will result if the springs lodge in other clutch system components.
Worn Stop Pins
Related Symptom: Chatter.
Cause: Driving in high gear at low RPMs, causing the disc torsion damper to contact the stop pins, high RPM engagement, excessive vehicle loading.
Worn Bearing Retainer
Related Symptoms: Hard pedal, incomplete release.
Cause: Incorrect release system adjustment, worn fork or fork pivot points, insufficient lubrication of the bearing retainer, worn ball stud causing the fork to apply uneven pressure to the release bearing.
For the clutch to function properly, the bearing retainer must have a smooth surface and be exactly parallel to the input shaft.
Embedded Friction Material
Related Symptoms: No release or engagement.
Cause: Harsh downshifting, high RPM engagement, engine over-revving caused by missing a gear.
The disc friction material burst when the clutch was disengaged, lodging friction material between clutch system component parts.
Melted Fingers
Related Symptoms: No release, extreme noise, slipping.
Cause: Worn bearing retainer, incorrect release bearing installation, worn or bent fork.
The release bearing seized and stopped rotating. The contact marks on the diaphragm fingers were caused by abrasion and heat from constant contact with the bearing. The release bearing would be melted, blue and/or destroyed.
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Call our Technical Hotline at 800.274.5001 for appplication, installation and diagnostic questions.
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