Schaeffler Group USA Inc.
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SERVICE HOTLINE
Call our Technical Hotline at 800.274.5001 for appplication, installation and diagnostic questions.
Our certified technicians are available from 8 am to 5 pm ET.
Slipping
Some slipping of the clutch is normal and necessary for smooth engagement; however, once the clutch is engaged, there should be no slipping. Excessive slipping causes tremendous heat that damages the clutch pressure plate and flywheel.
Normal wear is the most likely cause of slipping if the disc is worn down to the rivets and the clutch has high mileage. If a newly installed clutch is slipping, the most likely causes are oil or grease contamination, incorrect release system adjustment or improper flywheel machining of a stepped or cupped flywheel.
Slipping Diagnostic Procedure
Set the emergency brake and start the engine. Put the transmission in high gear and slowly release the clutch pedal.
- Engine immediately stalls: clutch is not slipping
- Engine continues to run with the clutch fully engaged: clutch is slipping excessively
- Engine slows but continues to run: clutch is slipping partially
Dual-mass Flywheels
If the vehicle is equipped with a dual-mass flywheel, the flywheel may be the cause of the slipping. Carefully examine the old clutch to rule out the flywheel as the source of the slipping. Indications include heat marks on the pressure plate, disintegrated disc friction material and contamination of the friction material from external leaks. If these symptoms are not evident, install a new flywheel.
| Causes of Slipping | |
| 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 Friction Material
Cause: If the clutch has high mileage, this wear is normal; however, if mileage is low, possible causes include riding the clutch, excessive vehicle loading, defective release system, improper release system adjustment, improperly machined flywheel, clutch components unsuited for the torque of a modified engine.
Overheated Pressure Plate
Related Symptom: Release problems.
Cause: Riding the clutch, defective release system, improper release system adjustment, clutch components unsuited for the torque of a modified engine.
The disc would have burnt friction material.
Friction Material Contact
Related Symptom: Chatter.
Cause: Flywheel not resurfaced or resurfaced improperly.
The flywheel must have a smooth, flat surface in order for the clutch to actuate properly.
Burnt Friction Material
Related Symptoms: Chatter, release problems.
Cause: Riding the clutch, defective release system, improper release system adjustment, clutch components unsuited for the torque of a modified engine, friction material contamination during installation.
Uneven Friction Material Wear
Cause: Riding the clutch, defective release system, improper release system adjustment, use of clutch components unsuited for the torque of a modified engine.
Pressure Plate Heat Rings
Related Symptoms: Chatter
Cause: Oil contamination, flywheel not resurfaced or resurfaced improperly, failure to maintain flywheel step/cup dimensions.
When resurfacing a stepped or cupped flywheel, be sure to machine the contact surfaces by equal amounts to maintain specified tolerances.
Grooves and Heat Marks
Related Symptoms: Release problems.
Cause: Riding the clutch, defective release system, improper release system adjustment, clutch components unsuited for the torque of a modified engine, improper resurfacing of a step/cup flywheel.
Contaminated Friction Material
Related Symptoms: Chatter.
Cause: Leaking transmission or engine seal, excessive lubrication.
Lubricate input shaft splines with a very small amount of high-temperature grease. Slide the disc on the splines to distribute a thin film. Remove the disc and wipe away any excess.
