The Holy Trinity of Better Braking
As people upgrade the engine and handling performance of their vehicle, a natural progression (and a necessary one at that) is to upgrade to a big brake kit (BBK). However, merely adding a larger rotor and caliper may not achieve the desired results. Braking systems are made up of more than just the caliper and rotor. The system is actually comprised of three main items working together in balance.
The Holy Trinity of Braking
Stopping power is not based solely on the caliper and rotor kit. The trinity is a combination of the caliper/rotor kit, pad type and tires. Their sum is greater than the parts, and as such, a compromise on any one of the pieces forces a compromise on the others.
1. The Big Brake Kit
BBKs come in all shapes and sizes. Most big brake kits feature more pistons per caliper than OEM versions. More pistons does not add more brake pressure, but instead spreads it out over a larger surface, helping to dissipate heat. Stiffness is one of the keys to a great caliper. AP Racing's mono-block race calipers are some of the stiffest money can buy and Sparta Evolution's two-piece calipers are some of the stiffest two-piece versions, machined from 2014-grade aluminum and bolted together with ARP fasteners.
The second key function of a BBK is to dissipate heat while using as little mass as possible. Brembo and AP Racing both manufacture mono-block calipers with a web-like design to keep air moving through the caliper. Another design detail that improves functionality through heat dissipation and reduced weight is castellated pistons, which is a standard feature on Sparta Evolution brakes.
Believe it or not, caliper finish also plays a part. Powder coated finishes retain more heat than an anodized or plated finish. Some custom powder colors also do not withstand the heat generated by track use, so context of use can play a role in the decision on what type of finish to use.
In order to save weight and rotating mass, two-piece rotors are highly recommended. Steel is the most economical and most common material for rotors. Carbon has a much higher resistance to brake fade on the track, but comes at a hefty price tag and requires special pads. Each rotor manufacturer has their own unique way of slotting and drilling the rotors. The function of the slots and holes is to scrub the surface of the pad to keep it from glazing and to help dissipate heat.
2. Brake Pads
Brake pads form the second part of the trinity, however, they are directly tied to the grip level of the tires being used. As the grip level of the brake pad increases, the grip level of the tires must also increase (and vice versa). Keep in mind that a brake pad with a large amount of bite on a non-performance tire can be dangerous.
There are many types of pads from a huge assortment of manufacturers. Hawk Performance (Carlisle Brake and Friction) and Performance Friction Corp are the industry leaders in pad development. Pad type is dictated mainly by the tire type used and also by driving style. Other factors to consider are how much noise, dust and longevity is required to meet your needs.
Driving type dictates what type of temperature range is required. Street pads typically need a lower initial temperature range compared to an autocross or road course pad. Picking the wrong heat range can result in decreased performance or worse. This is because racing and performance pads need to reach a minimum temperature in order to provide bite. Too little temperature and they can just glaze over.
When choosing pads, talk to the pad manufacturers and view their comparison charts. It is also beneficial to talk to other drivers or racers to see what works for them and their driving style.
Tire choice is often overlooked when considering a brake package. In the end, the tires are what physically stop the vehicle. Tires need to be matched not only to the power of the car but also to the power of the brake pads. Low grade or low grip tires matched to a set of aggressive track pads will cause the ABS system to trip too early and can also create issues with traction control. The opposite is also true, a too sticky tire matched to a lower torque pad can make the vehicle's stopping distance increase.
Just like pads, tire type is also dependent on driving style and environmental conditions. If the type of driving is normal daily driving, then a general tire would work well with an intermediate set of pads. If the roads are prone to rain or sand then a lower torque pad could work well with a set of wet weather tires. Dry track tires then would usually need to have an aggressive pad type. Again, it all comes down to context of use.
I talked with Hawk Performance to help me pick what pads would match the Nitto N555 G2s tires that were equipped on my Nissan 370Z. For daily driving, their 5.0 pads were chosen because of their low temperature grip. For road courses, they recommended DTC30 pads because they have a wide optimal temperature range and high levels of sustained bite. However, after a few track sessions, I noticed an imbalance. The car's ABS was being activated too quickly, which meant that the DTC30s were a bit too much for the N555 G2s with my new Sparta setup. The way to solve the imbalance was to go to a less aggressive pad or a stickier tire such as a set of Nitto NT05s. Since the DTC30s worked well with my driving style, I need to get the stickier tire.
Bottom line: Plan out the system to be installed and be realistic about the vehicle's use and general driving style. Not only will the vehicle brake better, but safety will not be compromised in any way.