Improving and upgrading the brake system on a car is often the last item in a car modification project, yet it is the most important element in terms of driver and passenger safety, as well as the safety of other road users. It is essential that you upgrade your car brakes when you increase the engine power of your car as the more powerful and faster your car is, the more efficient your brakes need to be to stop your car in an emergency. The same applies when you increase the weight of your car by installing a heavy ICE (in-car entertainment) system for example. In most cases a standard brake system is sufficient for stopping a standard car but when you improve the car's engine power the brakes may not be sufficient to handle the extra hp and brake fade may occur. Fortunately, there are a number of things you can do to improve your brakes. These range from fitting larger diameter ventilated brake disks (rotors), fitting multiple pot (piston) calipers, fitting cross drilled or slotted brake disks, converting rear brake drums to ventilated brake disks, fitting a larger master cylinder, fitting braided brake hoses, and using brake fluid with a higher D.O.T. rating (and boiling point).
In this section we'll discuss some options related to improving your car brakes but before we continue please be advised that brakes are critically important safety equipment. If you are uncomfortable with working on brake components, have a qualified professional do the work for you. Also note that your brakes are only as good as the grip of the tires on the road. If your tires have little grip because of worn shock absorbers of the tires are too narrow, upgrading your brakes will be wasted. So make sure your suspension and tires are in good condition before embarking in a brake upgrade.
Brake Disks (Rotors)
Brake disks are far less prone to brake fade than brake drums but they are not immune to brake fade. Thus converting the rear drum brakes to brake disks will greatly reduce brake fade but there is so much more that you can do to your brake rotors to optimize your brakes. If you have solid brake disks, replacing them with ventilated disks will improve the heat dissipation characteristics of the disks. You could also have the ventilated disks cross drilled or slotted. The holes in cross drilled brake discs help disperse heat and further reduces brake fade while slotted discs help to de-glaze the brake pads, ensuring better friction between the brake pad and the brake disc but they will wear the brake pads faster. Of the two, slotted brake disks tend to perform better than cross drilled brake disks but they transmit more vibration though the steering wheel and are noisier. You should also note that slotted brake discs are directional, in other words, the slots must turn in a particular direction. Brembo brake disks, for example should be installed so that the end of the slot nearest the outer edge of the disc comes into contact with the brake pad first but this may differ with other disk manufacturers. Make sure which way the slots should rotate and install them correctly.
Another option is to fit larger diameter brake rotors. A larger diameter brake rotor reduces the braking effort as it gives the caliper more leverage to stop the disc rotating and allows the car to slow down much quicker without causing too much build up of heat. However, there are two factors that limit the diameter of disc that you can use: the size of the wheels; and the relocation of the brake calipers. The wheel size will limit the size of the rotors but wheel may also limit the placement of the brake calipers, especially if you are using alloy wheels. This is important as when you fit a larger brake disk, the brake caliper must be mounted further away from the wheel hub. Thus, when fitting larger diameter brake disks you need to ensure that you can mount the brake caliper and that there is sufficient clearance better the caliper and the wheel.
There are two disadvantages of fitting larger diameter disks though. Firstly, when you retain the standard brake calipers, the area of the brake disk that comes into contact with the brake pads remains the same. This will result in rust towards the centre of the disc that will not be removed by the brake pad when you brake braking. If you fit a larger brake caliper then you remove this problem. Another disadvantage is that a larger diameter brake disc will result in an increase in the car's unsprung weight, which can adversely affect handling.
Increasing the size of the brake caliper will also increase braking efficiency as a larger brake caliper will have larger brake pads with a larger friction area that will be in contact with the brake disk. The larger the friction area, the quicker the car will stop and less heat will be generated by the brakes. And less heat means less change of brake fade.
A similar effect can be achieved by fitting a multi-pot brake caliper. Most standard brake disks have a single pot caliper. These calipers have only one piston that presses the brake bad against the rotor. By fitting multi-pot calipers with more than one piston, the additional pistons apply more force to the brake pads without requiring more effort on the brake pedal. They also spread the force out over the brake pad. However, multi-pot brake calipers, such as four-pot calipers are often manufactured without dust seals. These are fine for racing applications and are not appropriate for road use. If you are using a multi-pot brake caliper on a modified street car, make sure that it has dust seals.
The Master Cylinder
The brake master cylinder is often overlooked when it comes to improving the brake system; however, fitting a larger master cylinder reduces the effort required on the brake pedal and reduces the pedal travel required to pump enough brake fluid into the pistons on the brake caliper. This is more significant if you convert from brake drums to brake disks, as the pistons in the brake calipers used with brake disks have a larger volume than the pistons in brake drums. They thus require more brake fluid to be pumped to the brakes, which can be accomplished by fitting a master cylinder with a larger bore diameter. However, the master cylinder must match the flange on the brake booster, other wise you'd need to replace both the master cylinder and the brake booster.
Finally, if you want to eliminate a spongy feel on the brake pedal, you could replace the rubber brake hoses with braided hoses. Rubber brake hoses tend to flex under pressure while braided brake hoses are a lot less flexible, resulting in a firmer pedal action and better brake response. However, the spongy pedal may also be caused by water contamination in the brake fluid. Brake fluid is not compressible but water and air are compressible, resulting in that spongy feeling. Replacing the brake fluid and bleeding the brakes will eliminate the spongy feeling.
Now we have all our brake components fitted but we're not quite done; we need to change the brake fluid, bleed the brakes and bed the brake pads in. Changing the brake fluid and bleeding the brakes are two similar processes. You bleed the brakes through the caliper nipples to remove air from the system while ensuring that the brake fluid in master cylinder reservoir does not run low and allow air back into the system. When you change the brake fluid you bleed out the old brake fluid through the caliper nipples while again ensuring that the master cylinder reservoir does not run too low. You can use a turkey baster to remove some brake fluid from the master cylinder reservoir. This will reduce the amount of brake fluid that needs to pass through the system before the system is filled with clean fluid.
Bedding in the brake pads is another important process. Essentially, you want to put the brake pads through a heat cycle by increasing the temperature of the brake pads gradually and then allowing it to cool down. This can be achieved by performing about 30 light to medium brake applications of three seconds duration. Leave at about ¾ mile between each brake application. This will gradually increase the temperature of the brake pads without inducing thermal shock, and will mate the brake pad and disc friction surfaces. At the end of the repeated braking you should notice a little brake fade. Allow the brake pads to cool down by driving for several miles with little or no braking. Once proper cooling has been achieved, the system should maintain optimum performance at all temperatures.