Schaeffler Automotive Aftermarket USA


Up-to-date catalogs including complete product and technical information.

Clutch Catalog

Hub and Wheel Bearing Catalog


Call our Technical Hotline at 1.800.274.5001 for appplication, installation and diagnostic questions.
Our ASE-certified technicians are available from 8:00 am to 5:00 pm ET to answer your questions.

Clutch Diagnostics

Release Problems

When the clutch does not release completely, the disc continues to turn the input shaft and transmission gears. Common causes of incomplete release include excessive free play, air in the hydraulic system, binding or wear in release system components and a bent disc.

Movement of the master cylinder will also cause release problems. This is especially noticeable when the master cylinder is mounted to the firewall, and the firewall metal is not rigid enough to hold it in place during actuation. Any movement of the master cylinder reduces the force applied to the hydraulic piston inside, causing incomplete release.

Causes of Release Problems
External Internal
  • Contaminated hydraulic fluid
  • Incorrect release system adjustment
  • Air in the hydraulic release system
  • Defective or worn release system components
  • Defective or worn pedal bushings or brackets
  • Flexing of the firewall or any release component attachment point
  • Misalignment of clutch components
  • Corroded, damaged or improperly lubricated input shaft splines
  • Worn pilot bearing/bushing
  • Worn bearing retainer
  • Bent or worn release fork or pivot ball
  • Worn linkage components
  • Stretched release cable
  • Excessive or incorrect flywheel machining
  • Bent clutch drive straps
  • Bent or distorted disc
  • Improper transmission lubricant
  • Improper bolting of the clutch

Release Problems Pictorial

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.


Damaged Volkswagen Disc

Related Symptom: Noise.
Cause: Incorrect installation of the wire ring.

The wire ring was not properly seated during installation. After installation, the clutch must be cycled prior to start up to ensure the ring is fully seated under the tabs of the diaphragm spring.


Bent Clutch Drive Strap

Related Symptom: Chatter.
Cause: Excessive vehicle load, high-speed downshifting, lugging the engine, improper handling causing damage prior to installation.


Bent Disc

Related Symptom: Chatter.
Cause: Improperly supported transmission during installation, disc installed backwards.

Incorrect installation of the disc will result in interference between the disc and flywheel, causing clutch malfunction.


Burst Friction Material

Related Symptoms: Hard pedal, chatter.
Cause: Harsh downshifting, high RPM engagement, engine over-revving caused by missing a gear, coasting vehicle at a high speed with transmission in gear and clutch disengaged.

The clutch may have friction material embedded between the diaphragm spring and the cover.


Cracked Cable Housing

Related Symptoms: Hard pedal, chatter.
Cause: Incorrectly routed or pinched cable.

A number of problems can occur inside the cable housing, causing the cable to stick or bind. Always replace the cable on vehicles equipped with cable release systems.


Broken Segments

Related Symptom: Noise.
Cause: High RPM engagement, worn pilot bearing, worn transmission input shaft bearing, misalignment between the engine and transmission, improperly supported transmission during installation.

If the transmission jack is removed before the transmission is properly bolted to the engine, the weight will bend the input shaft, causing uneven engagement and partial release.


Flywheel Interference

Related Symptoms: Noise, problems with disengagement.
Cause: Excessive flywheel machining causing the disc to contact the flywheel mounting bolts, installing the disc backwards, failure to maintain proper flywheel step dimensions.

If the flywheel shows signs of extreme overheating and deep scoring, replace it.


Contact Marks

Related Symptoms: Excessive pedal free play, noise.
Cause: Incorrect release bearing installation.

The fork must be installed with the clip under the collar.

The fork was installed with the leaf-spring clip over the top of the release bearing collar, causing uneven force to be applied to the bearing.