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


Chatter is grabbing or jerking during engagement. The most common cause is contamination of the disc friction material. Before removing the bell housing, inspect the area around it and the engine to locate and repair the source of oil leaks.

Avoid contamination of disc friction material by touching it with clean hands only. Prior to installation, clean the contact surfaces of the flywheel and the clutch pressure plate with an alcohol-based cleaner.

Lubricate input shaft splines with a small amount of high-temperature grease. Slide the disc onto the input shaft splines to distribute a thin film. Remove the disc and wipe away any excess lubricant prior to installation.

Check the release system for wear and damage. Worn or distorted components prevent the clutch from clamping the disc evenly, causing chatter. Check the transmission and the engine mounts, and examine the vehicle for damage that could contribute to vibration as the clutch is engaged.

Causes of Chatter
External Internal
  • Loose or broken engine or transmission mount
  • Misalignment of chassis and drive line components
  • Worn or damaged universal or constant velocity joints
  • Missing bell housing dowel pins
  • Loose transmission cross member
  • Loose rear leaf spring bushings or spring u-bolt nuts
  • Worn or bent fork
  • Bent or broken drive straps
  • Warped or grooved flywheel
  • Missing flywheel dowel pins
  • Wear or excessive lubrication of input shaft splines
  • Worn pilot bearing/bushing
  • Worn bearing retainer
  • Worn or damaged disc splines
  • Clutch distortion or bent drive straps
  • Oil- or grease-contaminated friction material
  • Improper bolting of the clutch

Chatter 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.


Contaminated Clutch

Related Symptoms: Slipping.
Cause: Leaking transmission or engine seal.

On high mileage vehicles, always replace the rear main bearing and the transmission input shaft seals.


Friction Material Contamination

Related Symptoms: Slipping.
Cause: Leaking transmission or engine seal, contamination of the friction material during installation.


Bent Clutch Cover

Related Symptoms: Release problems.
Cause: Damage prior to installation, misaligned flywheel dowel pins, improper installation of the clutch.


Excessive Lubrication

Related Symptoms: Slipping, release problems.
Cause: Excessive lubrication of the input shaft splines.

On startup, the excess lubrication spun off the input shaft onto the pressure plate.


Chatter Marks

Related Symptom: Release problems.
Cause: Incorrect installation of the clutch. The clutch was distorted when it was bolted to the flywheel incorrectly.

Chatter marks were caused by the uneven actuation of the diaphragm spring fingers. Heavy finger wear would be evident on the diaphragm spring fingers opposite the chatter marks.


Uneven Finger Wear

Related Symptoms: Incomplete release, noise.
Cause: Incorrect installation of the clutch. The clutch was distorted when it was bolted to the flywheel incorrectly.

The pressure plate side would have chatter marks on the side opposite the lighter finger wear.


Excessive Finger Wear

Related Symptoms: Slipping, noise
Cause: Excessive bearing preload caused by riding the clutch, incorrect release bearing installation, defective hydraulic release system or cable self-adjuster, insufficient free play causing the bearing to ride constantly on the diaphragm spring fingers.

The release bearing may seize or make noise before slipping is noticed.


Broken Hub

Related Symptoms: Noise, engagement problems.
Cause: Disc was not properly aligned and the transmission input shaft was forced into the hub, shoving the center of the hub out.

The abrasion marks on the leading edge of the disc splines indicate the input shaft was forced into the hub. Never force the transmission into the disc or use the bell housing bolts to pull a transmission into place.