“wub wub wub” sound when the brakes are applied


My 2003 Chevy Malibu is making a “wub wub wub” sound when the brakes are applied. I can prevent the noise by starting to slow down earlier and gently applying the brakes. the last time my car was making a sound like that the repair shop said that my brake drum was warped. there is no change in how the brake pedal feels, or vibrations in the steering wheel. everything operates fine, there’s just that “wub wub wud” noise when brakes are applied quickly, firmly. Should I have gotten both brake drums replaced at the same time? do you think it’s probably the other drum needing replacing? I’ve never heard of a brake drum warping, but then I’m not a mechanic. hope you can help.

Hard to say without looking at it in person. However I will do my best. First off it is recommended to replace brakes in sets or pairs. Though there are exceptions such as a car being hit in one side, etc. The general rule and recommendations from Raybestos would be to replace both drums and or rotors at the same time. Along with the brake pads/shoes of course. The only way to know for sure would be to inspect the brake components.

Why replace both brake rotors or drums

Lets give you an example here. Suppose you made a hard stop on the freeway to avoid an accident. Now that the adrenilene has worn off you are starting to notice the car doesn’t seem to be itself. After a few stops you have pin pointed the issue when you apply the brake pedal. You hear a “wub wub wub” noise when coming to a stop the way you always did. Yep, your rotors are warped and possible the drums too(if equipped).

Though it is not often that drums warp, it does happen. And if the brake shoes wear down and are not replaced they will damage the drum and require replacement.

Brake Drum Inspection

  1. If any components are of doubtful strength or quality due to heat discoloration, or are worn, replace them.
  2. Inspect wheel cylinder dust boots for signs of excessive wear or damage. If any leakage is apparent replace wheel cylinder.
  3. Clean dirt and/or rust from brake drum, backing plate and all other components. Do not use compressed air or dry brush to clean brake components. Many brake components contain asbestos fibers which, if inhaled, can cause serious injury. Clean brake components with a water soaked rag or a suitable vacuum cleaner to minimize airborne dust.
    Any time the brake drums are removed for brake service, the braking surface diameter should be inspected with a suitable brake drum micrometer at several points to determine if they are within the safe oversize limit stamped on the brake drum outer surface. If the braking surface diameter exceeds specifications, the drum must be replaced. If the braking surface diameter is within specifications, drums should be cleaned and inspected for cracks, scores, deep grooves, taper, out-of-round and heat spotting. If drums are cracked or heat spotted, they must be replaced. Minor scores should be removed with sandpaper. Grooves and large scores can only be removed by machining with special equipment, as long as the braking surface is within specifications stamped on brake drum outer surface. Any brake drum sufficiently out-of-round to cause vehicle vibration or noise while braking or showing taper should also be machined, removing only enough stock to true up the brake drum.
    After a brake drum is machined, wipe the braking surface diameter with a denatured alcohol soaked cloth. If one brake drum is machined, the other should also be machined to the same diameter to maintain equal braking forces.