A rotor is a bumped disc sandwiched between the brake pads of your car. When you slow or stop, brake fluid exerts hydraulic pressure that causes the brake pads to grab on to the rotor. Usually, this system goes off without a hitch but, as rotors age, problems can arise. Bad rotors may endanger your vehicle and cause other undesirable consequences.
For best results in your braking system, your pads and rotor need to work well as a team. When they connect, abrasive or adherent friction causes your wheels to slow down and stop your vehicle. However, wear and tear reduce the ability for the pads and rotor to make and sustain contact. As a result, it takes longer for your vehicle to come to a stop. Obviously, the inability to brake quickly increases the chance of hurting yourself, your car, or others.
After significant use, expansion or contraction due to extended exposure to water, or old brake pads, rotors may warp. As a result, the pads will come in contact with the warped rotor when you apply the brakes. The pads pulsate, causing the wheels to shimmy and vibrate. You will feel these vibrations inside the car, especially in the steering wheel. These vibrations will be especially pronounced when making a sudden stop at a high speed but also will be noticeable at a routine stoplight.
A bad rotor will increase the wear and tear upon the overall braking system. It also may cause the anti-lock braking system to malfunction. As a result, the vehicle has a greater chance of locking up in a dangerous situation such as a skid or a deer caught in the headlights.
Additional problems caused by bad rotors include loss of torque at one wheel, loss of pressure at two wheels, reduced steering response, and even unattended steering input (for example, your car will drift leftward for no reason). Faulty rotors may also have difficulty dissipating heat that can lead to thermal stresses that reduce the rotors' own structural integrity and jeopardize the brake system as a whole.
