There's always time for a brake!

Brakes – part of going fast requires that one is able to stop as fast. The brake works with a friction pad, which is pressed against a Disc – the friction converts the momentum of the car into heat which is then dissipated over the brake disk slowing up the car. Heat is a big problem with heavy braking and a racecar must be prepped to cope with the high heat demands placed on the braking system. The braking force goes from the pedal into a magic box called a servo, which uses engine power to amplify the pressure of your foot decreasing the effort you need to expend. The pressure is transferred to the friction pads by means of liquid (brake fluid) inside a tube. At the brake pad end, which is subject to high temperatures, the fluid itself can get very hot. The benefits of using a liquid, which cannot be easily pressurised, means that the effect of braking passes along the tube (brake pipes) almost instantly. A cable would stretch a little and needs constant adjusting – most handbrakes use a cable system so you are aware how inefficient the cable brake system is also cables are more susceptible to the effects of heat and stretching.

The problem with brake fluids are that they are hygroscopic (they draw in water particles) which reduce the effectiveness of the transference process also at high temperatures they can boil – bubbles of air in the brake fluid create a spongy effect at least or at worst can completely prevent the brake from having any effect. Brake fluid should be checked regularly by a specialist for its boiling point which gives an idea of its degradation. Synthetic (dot5) brake fluids are not hygroscopic and have extremely high boiling points. Stainless steel braided hoses prevent any flexing and therefore loss of pressure at the pad end, they also look nicer and theoretically last longer too – get a full set and do front and back at the same time.

The heat is dissipated from the pad by the disks – a vented disc has a central channel which increases the surface to air ratio of the disk and created better and faster cooling. Drilled discs also increase the air ratio and along with grooves help to prevent a gas build up between the pad and the disk and keep the pads ‘clean and sharp’. Bigger disks = better cooling but bigger disks may require a different style of alloy wheel. The pads though are an essential part – the higher the friction the better. Racing pads are specially constructed from a high friction compound which works at much higher temperatures – a true racing pad will start working effectively only when it gets hot so this renders race spec pads useless for the road where braking most often happens on cold pads. I have found that fast road pads such as EBC Greenstuff is a very good compromise and have the added benefit of producing nearly zero brake dust and even last longer than the standards pads I was using – although driving style will effect the wear on the pad and on your disks.

ABS helps to prevent lockups under heavy braking and allows you to steer the car but steering will reduce the braking efficiency as the ABS cuts in more. ABS on gravel and snow can actually be a problem as the brakes are cut due to loss of traction whereas if the wheels where slowed a little the car could stop more quickly. Rally cars have a custom ABS setup which is quite different to standard road cars and maintains control and braking efficiency on gravel surfaces. Personally I leave brake work to the specialist as a failure would result in a certain accident.

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