What causes poor car braking performance?

[VanessaRose]

Poor car braking performance can be caused by: 1. Excessive free travel of the brake pedal; 2. Insufficient or no brake fluid in the master cylinder reservoir; 3. Air entering the brake lines or vaporization of brake fluid causing vapor lock; 4. Deterioration or wear of the master cylinder or wheel cylinder cups leading to poor sealing; 5. Clogged oil inlet holes of the master cylinder or vent holes of the reservoir; 6. Leaking outlet or return valves of the master cylinder. Braking, also known as deceleration, refers to the action of stopping or reducing the speed of moving locomotives, vehicles, other transport tools, or machinery. Its working principle involves fixing a wheel or disc on the machine's high-speed shaft and installing corresponding brake shoes, bands, or discs on the machine base to generate braking torque under external force.

[LeViolet]

I've encountered several instances of poor braking performance in my car. The most common issue is excessively worn brake pads, which make the pedal feel spongy when pressed. During my last maintenance check, the mechanic warned me that the rear brake pads were down to just 2mm. After replacing them, the pedal feel immediately improved. Deteriorated brake fluid also has a significant impact - when it contains too much water, bubbles can form, leading to longer pedal travel. There are also situations where the brake caliper seizes or leaks oil. A friend at the tire shop explained this causes insufficient braking force on one side, making the car prone to pulling during emergency stops. I recommend having a mechanic check brake pad thickness every 40,000 kilometers, and brake fluid must be replaced every two years. The iron dust buildup inside the wheel hubs also needs regular cleaning, as excessive accumulation reduces braking efficiency.

[Jeanette]

If you find your car's brakes failing, don't hesitate to take it to a professional repair shop for inspection. I've personally dealt with brake failures twice. The first time was due to a slight leak at the brake hose connection causing insufficient pressure, which was resolved by replacing the hose. The other time, the front brake discs were warped, causing the steering wheel to shake during high-speed braking. The braking system needs to be considered as a whole: wear on the master cylinder piston, leaks in the vacuum booster pump, or ABS pump failure are all possible causes. Nowadays, many cars use electronic parking brakes, and motor failures can also affect dynamic braking. Develop a habit while driving: at red lights, press the brake pedal firmly a couple of times to test for any changes in braking force.

[LaAdaline]

The core issue of brake failure is insufficient braking force. Possible causes include: oil contamination on the brake disc surface reducing friction; aging and hardening of brake pad material affecting engagement; low brake fluid level causing hydraulic transmission failure; cracked suspension arm bushings leading to brake position deviation. Low winter temperatures can freeze the handbrake cable causing lock-up. It's recommended to check the brake fluid reservoir level monthly by opening the engine compartment, and avoid washing the car immediately when brake discs are overheated to prevent deformation.

[Bethany]

During a self-driving trip, I once encountered a situation where the brakes became soft on a mountain road, which scared me into a cold sweat. Later, a check revealed that the guide pins of all four brake calipers were stuck due to lack of grease, preventing the pistons from pushing fully when braking. A clogged brake fluid reservoir filter can also hinder fluid replenishment. Excessive tire wear is equally dangerous; when the tread depth is less than 1.6 mm, it's especially prone to skidding in rainy weather, extending the braking distance. For vehicles frequently driven on highways, it's essential to check the brake disc thickness twice a year. During maintenance, ask the technician to inspect around the brake calipers with a flashlight for any oil stains, as rubber hose ruptures often start from there.

[DeOlive]

My old car started to have a harder brake pedal feel last year, and the mechanic detected a vacuum booster leak using a diagnostic tool. He mentioned that modern cars are equipped with a brake force distribution system, and a malfunctioning wheel speed sensor can also misjudge the braking force. It’s particularly common for the brake caliper pistons to rust and seize, especially after the rainy season, when you might suddenly notice longer braking distances. I’ve since developed a habit of checking the brake fluid’s moisture content every year when switching to winter tires before winter. A mechanic at a roadside shop taught me a simple test: after turning off the engine, press the brake pedal three times in a row—it should get progressively harder, which indicates normal function.