Brake System Components: Brake Rotors.

Good and Bad disk

The brake disc is the brake system component that the brake pads squeeze against to create a frictional force that slows down and ultimately stops your vehicle.

Brake discs are made of some form of cast iron material usually having two smooth or slotted surface combined together with a ventilation cavity in between to expel heat from the disc during braking.

The brake disc is a frictional component as it usually takes friction from the brake pads through out its service life.

The friction between brake pads and the surface of the brake discs causes some form of material loss each time the friction is applied hence the brake discs over time require some form of maintenance.

Depending on the type and quality of brake pads that you choose for your vehicle, your brake discs can become warped, grooved or deeply scratched over time.

A deeply scratched or grooved brake disc will impact negatively on the quality of your braking.

When you brake is grooved, yo may experience vibration and instability of your vehicle each time you brake.

You may also lose brake pad friction material more often than necessary due to grooved brake disc surfaces.

Most significantly, you may experience brake squeal and overall poor braking performance when you have a groved, warped or deeply scratched disc.



Your brake discs can become scared or grooved if you drive your car with a completely worn out brake pads and you allow the brake pad backing plate surface to run against your brake disc surface.

Your brake disc could also become grooved sooner than necessary if you repeatedly use brake pads with poor quality friction materials(with heavy wear effect) on them. Repeated usage of brake pads with metallic or semi-metallic friction material could also increasing wear on your brake pads as the pads friction contains a percentage of chopped steel fibre. Good quality Ceramic brake pads such as Du-Craft Premium Ceramic Brake Pads are much more gentle on your brake disc and have very low wearing effect.

The moment your disc surface has lost too much surface material, you will experience vibrations on your steering wheel and sometimes on the general vehicle each time you brake.

This reduces your stability and driving safety.


Your brake discs come from the factory with specified surface material thickness which usually has a minimum and maximum band. Over a period of braking your brake disc surface having lost surface material due to friction over time could become slightly patterned. Its is important to have your disc resurfaced or resurfaced with a lathing machine, an operation which takes off a very thin layer usually less than 0.5mm of thickness off your disc surface to produce another smooth and fine friction surface.

You should have your brake discs inspected for signs of grooves each time your brake pads are replaced. Once grooved, you should have them resurfaced or replaced completely if the surface thickness has gone below recommended thickness for your vehicle.Your technician could easily determine this by checking your disc thickness with a micrometer or a slide caliper and compare to the manufacturer’s minimum thickness specification.

Resurfacing your disc within recommended thickness specification saves you a lot on replacement cost as a good quality replacement brake disc could cost s fortune.

So before you change that disc, ask your mechanic to go the extra mile to check your disc thickness in relation to manufacture’s specification. Some vehicles discs come with about 20.6mm thickness and have a minimum thickness specification of 17.7mm.

If your disc still have sufficient thickness, taking off 0.5mm or less could restore your disc to a serviceable state and offer your another year or two of performance.

It is extremely important not to drive your car on a brake disc that has gone below thickness specification s this may causes serious problems such as disc failure, cracking or even ┬ábreaking. It also increase your braking distance sometimes up to 4meters. If you cannot find a mechanic to help determine your vehicle’s recommended minimum disc thickness, it is much safer to have your discs replaced in pairs.