Brake noise is the result of the linings and drum/rotor interacting with a given variable in the friction forces between these elements. This creates axial vibrations of the drum/rotor and component parts.

The following is a list of the most common specific causes of brake noise:
  • Poor lining-to-drum contact
  • Imbalanced braking condition
  • Type and condition of the suspension system
  • Brake drum design and weight:
    • Changing weight by machining on lathe
    • Machining with pointed tool
  • The condition of the brake component parts
  • The brake design
  • High friction materials used in light-duty applications
  • Linings contaminated with oil
  • Over-adjustment of component parts
    • Linings dragging against broken surface of drums
  • S-cams rotating reverse of wheel rotation
  • Shoes and lining rubbing drum wall
    • Return springs – broken, stretched or missing
    • Worn anchor pin
    • Worn anchor pin hole (shoe or spider)
    • Bent spider
    • Loose or bent camshaft
  • Linings loose on shoe
  • Camshaft bushings worn or need lubrication
  • Flat spots on cams or rollers
  • Brake chamber clevis pins worn or bent
  • Push rod and slack adjuster not aligned
  • Out of round drum
  • Automatic slack adjusters not set up properly.

(Note: All slack adjusters must be reset after each brake reline or new installation, following proper template. Haldex is the only slack which does not require a template because of its installation indicator on the slack).