Frequency of replacement: 40,000 – 50,000 Kms
When you step on the brake pedal, the master cylinder sends fluid under pressure to the brake calipers (which hold the brake pads). The caliper presses the brake pad against the brake rotor, causing friction that slows down the car. During normal usage of the brakes, brake pads wear out and become thinner. If the thickness of brake pads is less than 3mm, it is time to change the pads. Depending on where you drive (city driving tends to wear pads out quicker) brake pads usually last between 30,000 to 35,000 miles.
Frequency of replacement: the wear on your brake rotor depends on the driving habits and conditions. It has to be replaced on finding visible symptoms during inspection.
A brake rotor is a smooth metal disc attached to the wheel hub. Most new cars (1999 and above) come with rotors at each wheel. Older cars may have drums instead of rotors at the rear wheels. Brake rotors play an important part in the braking system. It is the friction between brake pads and rotors that cause your car to slow down and stop. As the rotors wear out (become thin or warped), they are unable to dissipate the heat caused by the braking system. This will cause the brake fluid to boil and reduce the effectiveness of brake system significantly.
Symptoms: ABS warning light in dashboard.
ABS have become pretty much standard equipment on most vehicles. Sensors tell a computer when a stop rotating, which indicates—at least when the vehicle still has forward speed—that the brakes have overpowered the available traction at that particular wheel. The computer then directs a hydraulic valve to release some brake fluid pressure to the wheel to let it rotate again. This process repeats many times per second until the vehicle stops or you lift your foot off the brake pedal.
The brake master cylinder contains brake fluid and is connected to the brakes through the brake pipes and hoses. When you step on the brake pedal, brake fluid flows from the master cylinder to the braking unit at each wheel, creating enough friction to slow down and/or stop the car.
The brake master cylinder has internal and external seals that can wear out over time. If the external seals have worn out, they will leak brake fluid, reducing the amount of fluid in the car and causing the brakes to malfunction. Worn external seals can also leak the fluid into the brake booster and destroy it. The brake booster is essential for the proper functioning of the brakes, so if brake fluid has leaked into it, replacement is required. If the internal seals have worn out, the brake fluid will continue to circulate inside, instead of being directed to the brakes. This weakens brake performance. The brake pedal will feel soft. When you apply the brakes, the pedal will go all the way to the floor without significantly slowing down or stopping the car. After replacing the brake master cylinder, the mechanic should flush the old brake fluid out and replace it with new brake fluid.