Vehicle Brake Maintenance
Just Right Autos in Witney can repair or service your brakes at any time. Here are a few tips on looking after your vehicle’s brakes.
During your vehicle’s lifetime, you should expect to have the front discs and pads replaced due to wear; however, surprisingly enough rear pads and discs are in need of more frequent replacements because of damage caused by corrosion.
Rust is more likely to set in if you use your car very little and always keep it in a garage.
Vehicle braking systems rely on friction to slow your vehicle down. Hydraulic pressure pushes brake pads against a cast-iron disc (or brake shoes) against the inside of a cast-iron drum.
When your vehicle is decelerating the weight (or load) is transferred to the front wheels meaning that the front brakes do most of the work when slowing the vehicle down.
Corrosion On Vehicle Brakes
Your brake components are mostly made up of cast iron, which is an ideal material but can corrode easily. The majority of braking force is done by the FRONT brakes therefore any rust on the surface of the discs is quickly rubbed off by the pads. The effort of braking is much less at the rear of your vehicle.
If your vehicle is small and light there may not be sufficient pressure or enough regular repetitions to clean corrosion from the surface of rear discs, especially if the vehicle is used infrequently or only for local trips.
The beginnings of ‘light corrosion’ may be cleaned off under a bit of heavy braking, but if you leave the corrosion it only gets worse.
Leaving it can lead to surface pitting, which can be acceptable but only if it does not seriously weaken the discs.
If you have drum brakes at the rear, corrosion is generally not a problem.
Wear On Vehicle Brakes
Front discs do wear and will eventually become too thin. All vehicle manufacturers specify a minimum brake disc thickness; for safety reasons. As discs reach this point, they must be replaced.
Discs should always be replaced in pairs and pads should be renewed at the same time.
Distortion On Brakes
Distortion in the disc is caused by uneven heating and cooling which may cause the disc to change shape. You can detect this by feeling a juddering through the pedal when the brakes are applied.
Worn discs, which are thinner, are more likely to warp than newer, thicker discs.
Avoid Brake Distortion
On long downhill runs do not slow the vehicle down using your brakes – this will put a lot of heat into the discs. Use ‘engine braking’ by using a lower gear. This will mean you need to use the brakes much less.
Hydraulic brakes work using the principle that you cannot compress a liquid.
Brake fluid absorbs water from the atmosphere even when your car is not being used. A lot of this water absorption takes place through the flexible rubber hoses.
If you brake heavily, for example on a long downhill descent, the brakes get hot and will heat the brake fluid. This boils the water in the brake fluid, which will vaporise.
Although you can’t compress a liquid (the brake fluid), you CAN compress this vapour. When this occurs your brakes will feel ‘spongy’ and full braking performance is lost.