Performance isn’t just about increasing speed and improving handling it’s also about stopping, so uprating your breaks is essential to increasing your vehicle’s performance. Before we can make an informed decision about what modifications we can make it is essential that we understand how brake systems work and what role each component plays.
Simply put, brakes work using a friction pad which presses against a disc, the friction created by applying pressure to the brake pedal creates heat which is transferred to the break disc which in turn stops the wheels turning. It is not surprising to learn that heavy breaking creates a huge amount of heat and a vehicles brake system and its individual components need to be optimised to cope with this demand particularly for race track conditions.
The force created when we apply pressure to the brake pedal is transferred into a device called a servo, by using the engine power it can magnify the pressure of your foot hence why a little pressure can go a long way.
This magnified pressure is then transferred to the friction pads via liquid in a tube, where this meets the brake pad the brake fluid can get very hot. Liquid is used as opposed to a cable because the effect of braking passes along the tube almost instantly, imagine squeezing a straw filled with liquid. In comparison a cable connection would wear and stretch and would require constant adjustment, as we know from most handbrakes which normally use a cable system.
However, brake fluid comes with its own issues because it is hydroscopic, which means in can draw in water particles which compromises its ability to transfer this energy. Also at high temperature it can start to boil thus producing air bubbles, which is what causes car breaks to feel spongy and at its worse can cause break failure, more information on dealing with this is on our website.
Heat is transferred from the pad to the discs which can be vented or drilled discs, both in their design allow heat to escape and cool quickly, therefore the larger the disc size then the more efficient they are. Obviously anti-lock brake systems are there to assist with preventing the wheels locking when braking heavily and therefore allowing steering to continue. However, it is worth noting that steering will compromise braking. But ABS on gravel and snow can be a real issue, as loss of traction causes the ABS to be cut, whereas if they were allowed to function and applied gently they could do their job. This is why rally cars, unlike standard road cars, have bespoke ABS with the ability to control when loss of traction occurs.
In optimising the brake system, pads are the key component, basically the greater the friction the better the brake. In fact, real racing pads, which are constructed from a special high friction compound, operate at significantly higher temperatures and only start to be effective when they are hot. This factor renders them unsuitable for road use, as they would need to operate from cold. As a compromise, TorqueCars suggest fitting fast road pads like those by Pagid and Black Diamond. Some of these have the adage of producing minimal dust therefore outliving standard road pads, although of course driving style will play a determining factor on both pad and disc wear.
By fitting larger discs you will reap the benefits instantly, you have more friction area and can dissipate more heat. As an example, take a basic 1.1 litre model car fitted with small discs, source and fit the larger brake discs and servos from a higher spec such as the 1.8 GTi. In fact, often you will find a manufacturer’s small car will have many of the same specifications as other models in their range so the brake system components are often compatible with higher models – you could ask our forum for examples. Don’t forget, when you increase the disc size you should also aim to increase the pads, callipers and pistons for the greatest result because more pistons means greater force which means you can use much larger pads.
Don’t forget, it’s essential that unless you are an experienced mechanic you should seek qualified specialist advice regarding any modifications to brake systems, as any brake system failure is almost certain to result in an incident.