Depending on the manufacturer, anywhere from .001" to .006".
worn thin
A disc brake rotor with excessive run out is a warped rotor which causes a pulsation in the brake pedal when the brakes are applied. A certain amount of run out is acceptable.
disc brake components
The rotor is the disc in the disc brake system.
Disc brake rotor? A pulsation in the brake pedal when applied. Distributor ignition rotor? The engine may not run or run poorly with misfires.
In case of cost..drum brake is better than disc brake.
There are many purposes to using a disc brake. Disc brakes are mainly used in industrial drills because the disc brake stops the drill gently so it doesn't overheat.
pad brakes are disc brakes, it's known as changing brake pads for disc setup and changing brake shoes with drum brake setup.
The teves caliper is a single piston disc brake caliper and the akebono caliper is a dual piston disc brake caliper. The teves caliper is a single piston disc brake caliper and the akebono caliper is a dual piston disc brake caliper.
It looks like a hydraulic clamp. When hydraulic pressure is applied with the brake pedal, the caliper clamps the disc brake pads to the disc brake rotor to stop rotation.
With rear drum brake:-The brake drum may be out of round or may have a rust spot in it. -The brake drum may be cracked.With rear disc brake:-The brake disc may have extreme lateral runout or be mounted improperly. -The brake disc may be cracked. This would be dangerous-Combination of soft brake pads and a directional finish on the disc surface. A directional finish may go away with use and take the noise with it.Regardless of brake type:A brake disc or drum mounted to a bent hub flange or bent axle shaft can cause this noise.
Most modern cars have disc brakes on the front wheels, and some have disc brakes on all four wheels. This is the part of the brake system that does the actual work of stopping the car.The disc brake is a lot like the brakes on a bicycle. Bicycle brakes have a caliper, which squeezes the brake pads against the wheel. In a disc brake, the brake pads squeeze the rotor instead of the wheel, and the force is transmitted hydraulically instead of through a cable. Friction between the pads and the disc slows the disc down.Vented disc brakes have a set of vanes, between the two sides of the disc, that pumps air through the disc to provide cooling.