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Confused About Car Brake Pads And Discs?


It’s not widely known but disc brakes have been with us ever since the latter years of Queen Victoria’s reign. The problem at the time was with the materials used; they wore out far too quickly. That’s why in the early days of motoring drum brakes were the preferred option. These used abrasive pads or ‘shoes’ to press against the revolving drum of the wheel.


They were effective enough but as disc brakes evolved it was clear that for sheer stopping power discs were the way to go. By the 1950’s they were starting to be fitted as standard; at least on the front wheels. Amazingly, drums are still fitted today on the rear wheels of some budget cars, purely to keep the costs down for the manufacturer no doubt, but discs brakes on all four wheels is usual now.


Cars are complex products in the 21st Century, what with software and a host of safety features but brakes are as important as they ever where. That’s why do-it-yourself servicing is largely a thing of the past: Far better to leave it to the professionals at your local car servicing garage. Even brakes have moved on technology-wise, what with callipers, pads, discs and safety features like ABS; but what does it all mean? Here’s some helpful information to make things clearer:


Overview

Behind the road wheels and seated either side of a brake disc are a set of callipers that hold a pair of brake pads just off the surface of the silver-coloured disc. When the brake pedal is pressed a hydraulic system ‘squeezes’ the callipers onto the surface of the disc, applying braking force.


Brake Pads

Most cars and other motorised vehicles use semi-metallic brake pads which are held in place by callipers connected to the vehicle’s hydraulic system. These pads, slightly rounded, are usually comprised of a mix of materials: Metal shavings of copper, steel, graphite, and brass, bonded with resin. Drivers environmentally concerned can specify organic discs made from natural materials which are effective but more expensive and like the disc pads from Victorian times, don’t last as long. They also create more dust, so it’s a personal choice.


Brake pads are relatively inexpensive and can last for many thousands of miles, obviously depending upon driver use and prevailing conditions. Every use of the brakes, wears down the surface a tiny amount. They are always checked at MOT testing time and your local professional garage will recommend replacement as and when required. Always check them as part of your annual service schedule as pads wear out faster than the more costly discs under normal use.


Brake Discs

Brake discs are flat, round pieces of steel that sit inside the wheel dish. As described above, applying the brakes makes the callipers grip the disc, slowing progress. Brake discs wear down every time a car’s brakes are used. Again, they can last a long time when used correctly. If the car has been standing in rain, it is likely that rust will appear on the disc surface. This is normal and not something to worry about as it will be cleared under braking.


Hydraulics.

Force is applied by hydraulic fluid being compressed when braking. This fluid has a reservoir chamber usually sited high in the engine bay. Routinely checking the level (on a cold engine) is an essential part of home car maintenance. From time to time, this fluid becomes exhausted and should be replaced. Your garage will advise. When it comes to brakes, there’s no cutting corners.


Driving

If, when applying the pedal, the brakes squeal or make other noises, or if the pedal itself feels spongy, then the pads or discs, or both, could need replacing. If in doubt, don’t delay, ask your local vehicle technician.


Regular servicing always makes a difference to brake longevity but it also helps if the car is driven moderately. Most experienced drivers know that on very familiar roads they can adapt their style to cut down on hard braking. On unfamiliar roads, observation and care with speed will also help minimise brake wear, saving money; something we all want especially these days, and making the components last longer.

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