Brake noise is a result of interaction of the linings and drum/rotor with some type of variability in the frictional forces between these elements, creating axial vibrations of the drum/rotor and component parts. Below are some of the most common specific causes of brake noise:
- Poor lining-to-drum contact
- Imbalanced braking condition (see brake balance).
- The type and condition of suspension system.
- Brake drum design and weight:
- changing weight by machining on lathe,
- machining with pointed tool
- The condition of brake component parts (see Reline Guides).
- The brake design
- High friction materials used in light-duty applications.
- Linings contaminated with oil.
- Over-adjustments of component parts
a) linings dragging against braking surface of drums
- S-Cams rotating reverse of wheel rotation.
- Shoes and lining rubbing drum wall
a) return springs – broken, stretched or missing
b) worn anchor pin
c) worn anchor pin hole (shoe or spider)
d) bent spider
e) 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. (All slack adjusters must be reset after each brake reline or new installation, with proper template. Haldex is the only slack which does not require a template because it has it’s installation indicator on the slack).