What Causes the Squeaking Noise When Applying Rear Drum Brakes?
2 Answers
Rear drum brakes making a squeaking noise when applied may indicate severely worn brake pads that need replacement. Brake pads are consumable items that gradually wear thinner with vehicle use. When the friction material is nearly depleted, a warning mechanism—the brake pad wear indicator—comes into play. This metal tab contacts the brake drum, producing a sharp metallic scraping sound as an alert. Considerations for brake pads are as follows: 1. Check thickness: New brake pads typically measure around 1.5cm thick, gradually thinning with friction. When visual inspection shows only about 1/3 of the original thickness remains (approximately 0.5cm), owners should increase self-inspection frequency and prepare for replacement. Some vehicle models' wheel designs prevent visual inspection, requiring tire removal. In such cases, if the warning light activates, the brake pad's metal base is already grinding against the drum, often visible as shiny metal particles near the wheel rim. 2. Listen for sounds: If light braking produces metallic scraping or squealing (which may also occur during initial pad bedding), immediate replacement is necessary. 3. Assess pedal feel: If braking requires significantly more effort or deeper pedal travel to achieve normal stopping power, or if the pedal feels abnormally low during emergency braking, the pads may have lost friction capability, mandating replacement.
I've encountered this issue several times myself, and it seems quite common. When the rear drum brakes squeak when braking, the most likely cause is uneven wear of the brake shoes. Think about it - the brake shoes directly contact the surface of the drum brake, and if they become too thin or uneven, they'll produce that sharp squeaking sound. Additionally, there might be accumulated dust or rust inside the brake drum, especially in older cars that have been parked for long periods without use - more rust means less smooth contact. Sometimes it's due to improper adjustment, like a loose adjustment screw or a detached spring, causing improper friction. Another factor could be the material of the brake shoes - overly hard materials tend to generate noise. I should remind you that this squeaking isn't a minor issue; ignoring it can lead to degraded braking performance, which becomes particularly dangerous on slippery winter roads. I recommend doing a simple inspection first to check for abnormal wear patterns on the wheels. If possible, have a mechanic take a look at a repair shop - maybe just replacing the brake shoes will solve the problem.
