Front and Rear Brake Pads

 

Automobile braking technology had undergone two significant enhancements during the recent past. The first occurred in the late thirties when Pascal’s Principle (in regard to hydraulics) was applied through installation of one Master Cylinder (linked to the brake pedal) and 4 Slave Cylinders installed on the 4 wheels, connected by flexible pipes. When the whole system was filled with hydraulic fluid and pressure applied to the Master Cylinder through the brake pedal, it immediately affected all the Slave Cylinders at equal force. In other words, when you stepped on your car’s brake pedal, all four wheels would slow down or stop, while the system became known as Drum Brake since it worked by way of Brake Shoes pressing against the brake drum and so reducing/ halting the momentum.

The other enhancement occurred much later when it was observed that as cars became more powerful and faster, drum brakes failed to provide adequate stopping power due to their design and structure. Also, they tended to overheat, thus becoming less responsive. As an answer to this inadequacy, a wholly new technology began to evolve in the shape of Disc Brake, where a disc or rotor attached to the hub is pinched or squeezed by a caliper with Brake Pads installed within it.

Difference between front and rear Brake Pads

Technically speaking, there isn’t much of a difference between front and rear brake pads installed in cars that feature Disc Brakes in both front and rear, save and except a slight variation in the rear for fixing the parking brake cable. However, when considering the braking system that is extensively used in contemporary cars that have disc brakes in the front and drum brakes in the rear, there is a gulf of difference between the two. In fact, it may require a marginal alteration in the title that should read Difference between Front brake Pads and Rear Brake Linings, instead of Difference between Front and Rear Brake Pads.

Brake linings mounted on Shoes featuring Drum Brakes at rear

Brake linings mounted on Brake Shoes are resistant to heat, while featuring high friction coefficient least affected by fluctuations in humidity, temperature or other elements. Materials normally used for manufacturing these components include friction modifiers, powdered metal such as zinc, brass, lead, aluminum as well as other materials that resist heat fade, binders, curing agents and fillers like rubber chips that tend to lessen brake noise.

Incidentally, the higher friction contact area of the lining mounted on drum brake shoes on the brake drum makes them more long lasting as compared to disc brake pads in any braking system of similar dimension and braking force.

Brake Pads featuring Disc Brakes at front

Brake Pads posses the unique quality of converting the kinetic energy of a vehicle to thermal energy through friction. Two brake pads contained in the brake caliper facing each other with the rotor in between them can clamp and squeeze the spinning rotor when brakes are applied hydraulically via the flexible brake hose. While the technology totally differs from that used in drum brakes, the pads too differ in shape, size and formation. What’s more, when a brake pad gets hot by coming into contact with the spinning rotor, they transfer minute quantity of friction material to the rotor body, as a result of which they tend to ‘stick’ to each other that slows or stops the rotor, as also the vehicle.

However, Rear Brake Pads are available in several varieties and types that are outlined below.

Non-metallic Brake Pads that are made from an amalgamation of several synthetic materials are effective for a limited period. However, they are gentle on rotors.

Fully metallic Brake Pads that are made from sintered steel are much more durable, but again are very hard on rotors. However, these are ideally suited to the requirement of racing cars.

Ceramic Brake Pads that are composed of clay and porcelain (and are burnt in a kiln) has the durability of fully metallic brake pads, while featuring the grip and fade resistance of the synthetic type, and so are cherished by all but bought by few because of their high price range.

Postscript

Studies reveal that Brake Pads for Disc Brakes in the front and Brake Linings mounted on brake shoes for drum brakes in the rear seldom go out of order concurrently. However, even if such a situation ever arises, the best course of action (in regard to Disc Brakes) would be to follow the car manufacturer’s specifications.