Brake discs, callipers and pads, are the essential parts of a car's braking system.. Having the right components greatly affects the effectiveness and efficiency of a car's stopping capability. A servo, fitted in all modern cars, assists ther driver's braking effort by multiplying the actual force applied to the foot pedal to the brake pads via the caliper, the brake pads and the brake disc. Because of the friction and the heat generated in the pads and discs it is one of the most common items of wear found on sevicing and of course during the MoT test. Not only does the friction material wear, so does the metal on the surface of the disc and it is not unusual, due to the naturally aggresive material of the pads themselves that discs will wear or even warp out of shape. In itself, apart from the very specialist discs and pads fitted to some high performance cars, this is not an expensive maintenance item and will provide much safer braking than new pads fitted to worn discs.
It is very unusual for there to be any maintenance or repair due to component failure with the servo unit and generally, if it does fail, replacement is the only course of action as they are not designed to be repaired.
The brake fluid reservoir is an imprtant part of the system as it hold, as the name suggests, provides the brake fluid required by the braking system. It is not unusual for there to be a slight loss of fluid which will compensate for the wear on the brake linings or pads. However, if it requires topping up frequently, the brakes should be examined in detail to ensure that caliper or brake cylinder seals are not leaking. Loss of brake fluid from a leaking seal could cause a catastrophic loss of stopping power in an emergency.