They say bigger is better and it’s certainly one aspect that applies to the brakes in your car. It’s one thing to bolt on bigger and badder brake discs, calipers and brake pads, but what does it all mean and how does it work? Before you make any choices on what brake upgrade you want to go with it’s best to understand how brakes work. That’s why this guide to understanding brake tech is for.
If you are upgrading your vehicle with the intent to increase horsepower, you need a good plan on how to upgrade your brakes to match. If you’ve ever wondered how brakes and brake upgrades work, this brake tech article is for you. Today we’ll be discussing what makes your car stop and what makes up your braking system. Before we delve into the technical aspects of this guide, lets briefly recap how your brakes work.
How Brakes Work
Most modern brake systems are based on the disc and caliper brake system. The easiest way to understand how your disc brakes work is to imagine that they are a plate and clamp. The plate operates as your brake discs, and the clamp is acting as your brake calipers.
As you push your brake pedal down, your brake hydraulic system compresses your brake caliper. The caliper pushes your brake pads into the disc rotor, this creates the friction required for your vehicle to start. Simple.
The efficiency of your disc brakes or how well they work isn’t quite as cut and dry however. There’s a lot that goes into this equation; materials used, positioning of the caliper, diameter of your brake disc, and so on. To understand more about the variables that determine how well your disc brakes work, read on.
Brake Tech – Diameter of disc brakes
Your brake discs are there to provide a surface for your calipers to clamp onto. Because it’s basically a friction based system, changes to the material and size of your brake discs will make a huge difference. One of the biggest changes you can make to the disc is the diameter. Disc diameter is usually what changes between the performance brake kits and the factory brakes.
How does the brake diameter make a difference? – The larger your brake discs the greater leverage or brake torque advantage you will have. Try to imagine a dime acting as your brake disc.
If your vehicle was traveling at 50 MPH, it would take a lot of clamping force to get the brake torque required to stop. This is because the distance between the center of your dime sized brake disc and the outer lip, or the radius is extremely small.
Now imagine your rotors are the size of a large pizza. The increase in radius will give your calipers the surface area, or leverage it needs to stop effectively. Because you’ve got more brake torque you won’t need as much clamping force to stop the car.
Brake torque is a simple equation that’s calculated by using force x distance. Placement of your brake caliper also plays a big role in the brake torque. If the brake caliper is mounted closer to the center of the disc, there will be less brake torque or leverage. This is why most performance vehicles utilize larger brake discs with the caliper mounted towards the ouside of the brake disc. This is why so many people opt to upgrade their brakes with a more aggressive setup using a brake swap guide.
Width of disc brakes
After the diameter of your brake discs, the width is another huge determining factor. Although the width of your disc brakes is certainly important, it doesn’t improve your braking ability. Instead the width of your discs helps to keep your brake discs cool. Many aftermarket rotors will come with cooling vents that are integrated into the width of the rotor.
Vented brake discs mate both friction surfaces and sandwich them between cooling vents. Brake vents help dissipate and combat heat caused by the friction required to stop your car. These vents spiral out from the center of your brake disc, and act like a fan to quickly decrease brake temperatures.
As your brake discs spin, air travels between these gaps to cool the rotor. The wider the gaps in your vented discs, the greater the cooling effect. Keeping your brakes cool and operating within the proper temperature range is critical. While most vehicles are not in danger of overheating their brakes, it can occur during heavy towing, or extreme usage in competition events.
On the track or during race conditions, prolonged heavy usage of your brakes can cause them to overheat. When your brakes get too hot the hydraulic system that your disc brakes operate on will not work as well. This can cause them to stop working and your brakes to fail. This is otherwise known as brake fade.
Disc Brake Material
The material that your brake discs are made of is the next factor that plays into your braking equation. Many brake systems use rotors that are a combination of high-grade iron alloy. Iron alloy is resistant to cracking and distortion and is relatively inexpensive, making it an excellent choice.
These iron alloys can be comprised of different levels of another compound or metal. Different iron alloy composites will have a wide range of frictional properties. These brake materials can range into higher friction materials such as carbon-ceramic rotors or full carbon discs. As the name of carbon-ceramic brake discs suggest, these rotors are made up of ceramic and carbon composites. These brake rotors are lighter, which improves performance and wear slower because they are more durable.
Top end brake systems use full carbon brake rotors. There is a lot of engineering and brake tech that go into this kind of brake system. These are used in high competition situations and applications such as F1. Carbon brake systems offer a high temperature dispersion ratio, and are highly resistant to brake fade. Further they use higher frictional properties which makes them superior brake systems. Carbon brake pads are used in this kind of application which can also make them last much longer. Brake tech doesn’t get any more advanced than in carbon-carbon brakes.
Brake Rotor Construction
Brake rotors are made in either one-piece and two piece designs. Most factory brakes in vehicles utilize a one piece brake design. One-piece discs are made from a single piece of
material, which makes them cheap and easy to maintain.
Two piece rotors are used in high performance brake kits and upgrades. They are made from a rotor that is bolted to what’s called the brake bell.
The bell is usually made from an aluminum alloy and is the center section that bolts to your hub.
This makes the rotor or the outer ring the part that your caliper clamps onto. There’s two different ways in which these rotors are designed. Two piece rotors utilize floating and fixed brake tech. Fixed brake bells and rotors are just bolted together.
These are typically made of similar materials to keep the heat expansion rate similar or close to one another.
The other kind of two piece brake rotor is the floating type. Using this brake tech the rotor and bell are connected through a series of floating discs.
This style of brake tech allows high performance brake systems to excel. Because the floating brake rotor can expand
independently of the bell, it reduces the chance of warpage and keeps your calipers and brake pads working with maximum surface area.
Brake Rotor Surface
The surface of your brake rotor can help improve and upgrade the braking efficiency. There are many different types of rotor brake tech that are implemented into the surface of your brakes. Most factory brake rotors are smooth by design, and are durable because there is less chance of cracking. They are common in factory vehicles because of the low noise levels and they are much cheaper to produce.
When your brake pads clamp onto your rotor, the friction can create gasses that can decrease your braking efficiency. Different kinds of brake tech involve grooves, slots or cross-drilled holes to improve braking power. Cross drilled brake rotors allow the hot gases to escape from the disc face and your brake pad. It can also allow you to keep the face of your brake rotor clear from dust and cool under most conditions.
Cross drilled brake tech does have it’s disadvantages however, by nature drilling a hole into something makes it inherently weaker. If the rotor is exposed to extreme heat cycles there’s a good chance of cracking occurring at the brake holes.
Slotted or grooved brake rotors can also improve the initial “bite” of your brake disc. The leading edge of the groove or slot cleans the brake pad and clears it of any debris, creating a better initial contact situation. Curved groove brake tech can also help in many different ways. Some upgraded brake rotors can offer increase initial bite, and upgraded friction between the brake rotor and the pad.
One of the biggest factors to your brake system are your brake pads or shoes. These are the primary friction device that applies pressure to your rotors to slow your car. This component physically causes the friction through a variety of materials and compounds.
Depending on the manufacturer and brake pad, there’s several compounds that make up your pad.
These are typically closely-guarded trade secrets and can range in materials like ceramic or metallic compounds.
For every different kind of brake pad compound your brakes will react and perform differently. Some brake pads will work better when cold, while others will require you to warm them up. There are even advanced brake tech used in pads to keep brake dust to a minimum. These can really help you keep your wheels clean and both you and your passengers safe.
Brake Tech – What is a brake caliper?
The brake caliper is what pushes the brake pad into action. It’s driven by hydraulic pressure sent through your brake master cylinder. There’s several different caliper brake tech systems to choose from. One piece brake calipers as well as two piece split calipers. This part of brake tech is also extremely helpful when you upgrade to a larger bore brake master cylinder.
In the case of one piece mono block brake calipers, they are mostly used in high competition situations. Where weight and and caliper flex are considerations, single piece calipers are usually cut from billet alloys. Although one piece calipers are not as resistant to caliper flex as split calipers, they are mainly used in race car applications.
That’s because race cars use less brake line pressure, which results in less caliper flex. For most performance and factory brake systems however, the split caliper is ideal.
These two piece calipers come with a floating or sliding type of caliper. The brake tech at work here uses a piston on one side of the two piece caliper. This caliper is attached to the sliding mechanism that’s bolted to the hub.
The two piece caliper isn’t directly fixed to the hub so the position in relation to the disc can change. When you press down on the brake pedal, the piston presses one pad to the disc which will compress the caliper to slide and pull the other pad on the backside of the rotor.
Although this style of brake caliper is easier to maintain, most performance calipers are better as fixed units. Fixed brake calipers are an incredible piece of brake tech. By bolting the caliper directly to the hub and using pistons on either side, there is a lot more braking power. As you push down on the brake pedal, the brake fluid is forced into both sides of the caliper through a bridge pipe. This forces the pistons out of the caliper housing and presses both brake pads into the face of your brake rotor.
The number and size of your brake pistons will affect the braking characteristics and brake power. Another aspect of brake tech that many people fail to realize is the caliper mounting. Mounting of your brake caliper occurs either on the lug or radial mounting. Lug mounted calipers are mounted axially onto the hub. It’s cheaper and a simpler design as there’s no need for a bracket between the caliper and hub.
However this style of brake caliper mounting is also much more susceptiable to brake caliper flex. Most performance brake systems are mounted radially using an brakcet that mounts to the hub. You can also use this style of caliper mounting to switch and upgrade your brakes and brake calipers.