Car Brakes |
Car brakes are one of the most important performance upgrades you can make to a car. Your car's brake performance must match it's power and handling for the car to be competitive. There is no point being the fastest car on the road or track and when you need the brakes to stop, you can't make the turn. Normally performance brake upgrades would come in different stages, including uprating the brake pad material and using larger ventilated two-piece disc/rotors, also steel braided brake lines, larger calipers and different brake pad materials are a few of the options available. Braking systems are a integral part of a good performance package and there a lot of effective products out there. The disc brakes which causes the wheels to stop rotating are a device mounted normally on each wheel axle and we will only cover this type rather then drum brakes (low performance potential and considered primitive technology). A brake disc/rotor can be made of a number of different materials including castor iron ceramics and composites (including carbon, kevlar and silica). These material usage is in an attempt to reduce brake fade, increase heat dissipation and the cars stopping power. The brake disc is connected directly to the wheel or axle and friction material called brake pads are mounted on a brake caliper and activated via the a foot pedal and brake pistons.These can be forced mechanically, hydraulically,pneumatically or electromagnetically, against both sides of the disc, converting kinetic energy into heat. This friction that this causes between the disc and pad, slows or stops the wheels rotation and this process generates high brake temperatures, in many high performance applications you will see the disc glowing amber or red hot. |
Normally a standard braking system will consist of a brake pedal which is connected to a master cylinder containing brake fluid, this in turn is connected to the slave cylinder which has a piston that pushes the brake pads against the discs on activating of the brake pedal.
This action of effectively clamping the materials together (brake pads and discs), is what converts the kinetic energy of the moving wheels into mostly heat and effectively slows the rotation of the wheel down.
In high performance car models this has been engineered into the equation, but like most things which are sold; everything has a mark up and budget. By using a combination of different materials you can effective increase braking performance significantly. Especially on less expensive, mass produced car models intended for motorsport use.
In a emergency driving situation, you need the brakes to work as quickly and as effectively as possible, at maximum capacity. This is where ABS (Anti locking braking system) can make the difference between a fatal accident or a near miss.
In the old days when you applied too much brake pressure on the pedal, the road tyres/tires grip levels would be exceeded. This in turn would result in the wheel locking up and up to 30% of the maximum braking capacity of the car could be reduced. Also all the turning inputs of the steering wheel would be pointless due to the fact of the tyres/tires already pass their performance limit. In any one time a tyre/tire can only have a certain percentage of acceleration, braking and turning. This is referred to as the traction circle. When maximum braking is deployed in a straight line,it is referred to as Threshold Braking.
The only way of returning the full braking efficiency is to release some of the brake pedal pressure, this will unlock the wheels and regain maximum braking effort. Also further release of the brake pedal will return more and more of the turning ability of the car.
A car's level of grip and it's attitude under weight transfer from heavy deceleration affects the brake balance of the car. As you increase the performance of a car, you may need to adjust brake balance to maximise braking effort. Also to re-balance the Understeer and Oversteer equilibrium to maximise performance upgrades.
In the world of automobiles, the faster you want to accelerate; the more power is required to overcome the air resistance and drag. Regenerative braking is a way to save and store some of these energies used to move the car.
In a conventional (or electrical) car, torque is required to move the wheels and frictional losses causes inefficiency. The same losses occur when you apply the brakes and this energy is converted from movement (kinetic) to heat, in an aid to slow down the car. It is a lose-lose situation in terms of energy loses,and is essentially a inefficient technological set up.
- Regenerative braking losses efficiency at lower speeds is reduced, also it can not bring the car to a total halt or be used effective for locking the rotors totally ( used in hill starts for example).
- In FF or FR ( see drivechains ) configurations, four wheeled braking is needed in wet or slippery conditions to maximise stability. In a 2 wheel electric drive set up, this will not be possible on the other wheels.
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Under emergency braking conditions, it is required to have maximum braking capacity all the way through the speed range. As regenerative braking is less efficient at lower speeds, this will be unacceptable. Also in some cars ( non performance models), the maximum forces of their acceleration capacities are a lot less then their braking capacities. So on a production point of view, they would need larger capacitors just for braking then is required to provide drive.We have seen a more wide application in these technologies in the automotive world with cars like the Toyota Pruis. I suppose this is just the start for these Innovations in the General Automotive world and even Motorsports. Take F1 KERS ( Kinetic Energy Recovery System) for example, plans to reuse some of this wasted losses and further increase the performance are currently under way and will feature in the 2011 calendar, as originally developed in the 2009 season. See Brake Upgrades for more details.
