Brake Systems

This section will explain both how the brakes on your car work, when they should be replaced and MOST importantly, how.

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How the brakes work.
When you push the brakes pedal, the hydraulic fluid, (that can not be compressed) passes from the master cylinder, (at the end of the brake pedal) through the lines to the brake calliper, at the wheel. The % is varied front to back but more on this later. The additional fluid pushes out the pistons against the pads which "squash" against the disc, (from both sides). This creates friction resulting in the pads heating up and dissipating the energy. As well as wearing out. This is why sports cars, rally cars and most heavy road cars have vented discs these days, to dissipate MORE heat quicker, plus MRT's latest discs are also slotted to remove dirt and improve pad performance.

Brake Balance
As cars have varied weights front to rear, so they also need less braking front to rear, this is brake balance. On most rally cars rear balance is higher so drivers can put the car sideways if needed by locking up the rears' before the front. Vans are obvious unladen they have little weight, low grip, and given the same pressure will lock up well before the front. This is generally unsafe and manufacturers build in systems that ensure the front lock up first.

Anti lock brakes
When you lock up the wheels from excessive pedal pressure, you have no steering, the point of MAXIMUM braking is at the limit of the wheel before it stops turning. ABS (antilock Braking Systems) rapidly compare road speed to wheel rotation speed and pulse the hydraulic fluid to maintain this point of maximum braking. The quicker the sensors in judging the two input speeds the better the stopping distance. NOTE a Good driver, in theory should be able to stop a car in a shorter distance than ABS ! As every "off" pulse is a short distance extra in stopping.

Servicing
All brakes should AT LEAST be inspected every 10,000 km and fluid replaced every 40,000 km. Minimum. The longer brake fluid is left, the MORE water is soaks up from the air, and at high temps this water boils and causes brake fade. Most cars have original fluid until 40,000 km service.

Replacing
Never, replace discs and pads at the same time, (unless necessary). A common mistake is to wear out pads to the hardened backing plate then damaging the disc. This often results in both disc and pad needing replacement. Other than this, new pads should be fitted with old discs and new discs with old pads. WHY? Because with heat discs form a hardened\ surface allowing them to "bed in pads that are soft. Pads too, when old are well "heat treated" and allow "green" discs top be bedded in. NOTE never unless stated by supplier "stand" on the brakes with new discs or pads. Excessive heat early in "running in" overcook the parts and result in poor life.

Bedding in
These days, (unlike past) the way to bed in new brakes are as follows. AT MRT we use a simple way to describe it! Its like cooking a chicken, cook it hot and fast and it will be terrible, but slow and long and it will be sweet and enjoyable. Like chooks, brakes need time and low temps to bed in, the longer the time and more frequent the cycle of cold and warm, before the "big test" the better most pads and discs will perform. On our rally car we often get my wife to bed in the pads before we fit them to the rally car, as we have little time to bed them in, Sydney traffic is good!

Pad design
All brake pads are NOT the same, you get what you pay for, either fade, low life, dusting or many other hassles. MRT sells many different types, however the ones we suggest for you may be different to another driver in the same car! WHY? There is no need for you to pay for racing pads if you never fade std types, its a waste of money, however if you tow heavy loads, then it may be worth considering. Pad consistency is also important, if you have a steady rate of deceleration you don't want the pads to lock up when you least expect it, in emergency situations, they need to be CONSTANT in all applications. Poor quality pads often (in addition to fading early) are not consistent and cause premature lock up resulting in loss of control.

Brake squeal
Often a misunderstood problem. Squeal is high frequency vibration often between pad and disc. Most pads have built in "anti squeal shims" or as well as on the calliper. "Anti Squeal" paste or fluid can be used, but resist applying to the friction surface, as it is then also anti brake! It is simply often a way to absorb the vibration. Machining the disc can often rectify the fault. OR in some cases, a big long HEAVY brake, as it may be poor surface, or be careful a situation where the pad has become shiny like a mirror and loses its grip. To fix this, removal of the pad to remove this shiny layer is needed.

MRT on Brake Systems