What Could Be Wrong With Brakes: the Brake Pads Are OK, but the Car Does Not Stop Well
Modern brake systems work under the same basic principle they have used since the 1890s: apply friction to the wheel and the vehicle stops. ...
Modern brake systems work under the same basic principle they have used since the 1890s: apply friction to the wheel and the vehicle stops. However, unlike the wooden blocks used in the 1890s, modern vehicles use brake pads that press against a rotating metal disc -- rotor -- to stop the vehicle. There are five main reasons, aside from worn-out brake pads, that may cause your vehicle not to stop well.
Failed Master Cylinder
The master cylinder is the heart of your vehicle's braking system. It creates the pressure needed to press the brake pads or shoes against the rotors or drums. If a seal in the master cylinder begins to fail, the pressure in the brake system may not be high enough to create the friction needed to stop the vehicle. This lack of friction can cause your vehicle to not stop as well as it usually does. When this condition occurs, you must either rebuild or replace the master cylinder.
Failed Brake Caliper of Wheel Cylinder
Depending on the type of brake system your vehicle has installed -- drum or disc -- the calipers or wheel cylinder press the friction components -- pads or shoes -- against the disc or drum. If one of the two components develops a slight leak, or seizes, this will cause the vehicle to not stop as well as it typically would. Depending on the reason for the failure, you can either rebuild or replace the failed wheel cylinder or brake caliper.
Brake Lines and Hoses
The brake lines are metal lines that run from the master cylinder, under the car, connecting to rubber hoses that deliver the pressurized brake fluid to the caliper. If one of these lines or hoses begins to leak, it causes a loss of pressure in the brake system, resulting in poor brake system performance.
Another problem is created by the collapse of a line or hose. If a line or hose collapses, the brake fluid cannot effectively flow to the calipers or wheel cylinders, which causes poor braking performance. Replacing the leaking or collapsed line is the only remedy in this situation.
Glazed Rotors
The brake system requires a lot of friction to stop your vehicle. Dues to this need for friction, the pads and rotors must have a rough surface to create maximum friction. Over time, heat and friction can cause the rotor to glaze -- develop a mirror-like shine and smooth surface -- which is not an optimal friction surface for the pads to grip. In severe cases, this can cause a significant decrease in braking performance. Resurfacing or replacing the rotor is the only way to rectify this problem.
Air in the Brake System
The hydraulic systems used by modern vehicles are sensitive to even the slightest amount of air present in these closed systems. Small air bubbles may cause sudden decreases in hydraulic pressure, which can result in extended braking distances -- even a total loss of the brakes. The brake system has a bleeder valve on each caliper or wheel cylinder, so this condition can be remedied by bleeding the air from the system.
