There is perhaps no more exhilarating spectator sporting event than a NASCAR race. With speeds sometimes exceeding 200 miles per hour and minor contact between vehicles not only permissible but a strategic part of the sport, success depends not only on driver skill but the equipment itself. Contrary to popular belief, one of the most crucial components on a winning car is its braking system.
What type of brakes are found on NASCAR cars? For NASCAR’s stock car racing circuits (series), all cars are mandated to have disc brakes on all four wheels. NASCAR rules and regulations restrict the materials that may be used for certain components (the rotor in particular) as well as the particular specifications of the calipers, pistons and brake pads.
Stock car racing is a sport where the slightest advantage in weight or aerodynamics can make the difference between taking the checkered flag and finishing second. This certainly applies to a NASCAR vehicle’s braking system, and as we will see in this article, not only is each component of the disc braking system scrutinized, but these components can change from event to event and track to track.
How Are NASCAR Disc Brakes Unique?
NASCAR (the National Association for Stock Car Auto Racing) is the world’s largest governing and sanctioning body of professional stock car racing. To promote fair competition, NASCAR strictly regulates many specifications of competing vehicles, including engine size, length and width of cars, aerodynamic attributes and even the braking systems.
All NASCAR cars must have disc brakes on all four wheels, with rotors manufactured from magnetic cast iron or steel, with a diameter of no more than 12.72 inches. There are also restrictions on the type and make-up of the brake calipers with no more than six pistons allowed for the front brakes and no more than 4 pistons permissible for the rear calipers. Brake pads feature state-of-the-art materials.
NASCAR racing events are held at different racing venues throughout the season. For instance, the premier stock car racing circuit known as the NASCAR Cup Series comprises 36 races held at different tracks across the country. To maintain competitiveness race to race, teams will adjust the braking system on their cars to specifically suit whichever course they will be racing.
Why does the Track Matter?
There are two main types of tracks on which NASCAR runs its races, ovals and road tracks. Oval tracks are closed-circuit courses and as the name suggests, oval-shaped. Cars usually travel in a counterclockwise direction and only make left turns throughout the race. Road tracks are courses on which both left turns, and right turns are made. The vast majority of NASCAR races are run on ovals.
Different race tracks, particularly ovals, require different race strategies and driving styles. These factors, in turn, determine the specific braking system characteristics that are needed on a given race day. Considering that the typical NASCAR Cup Series vehicle weighs 3,200 pounds without the driver or fuel and can achieve speeds of about 200 miles per hour, braking system decisions can be critical to success.
The Different Types of NASCAR Race Tracks
In a typical NASCAR Cup Series season, all but three of the 36 races are held on oval tracks. Although each racing venue (often referred to as a “raceway” or “speedway”) is distinct in layout and has its own unique attributes, ovals can generally fall into one of three categories.
- Short Track – these are race courses that are less than one mile in length. Because they are more compact than their speedway and superspeedway counterparts, short tracks typically have sharper turns and shorter straightaways.
Notable Short Track Courses: Martinsville Speedway (Martinsville, VA), Bristol Motor Speedway (Bristol, TN)
- Speedway – also known as “intermediate” tracks, speedways are the most common type of oval and have lengths greater than one mile and less than two and a half miles. Within these parameters are a wide variety of track features, including tri-oval courses (hybrid between triangle and oval shapes where one straightaway is bent to form a peak) and D-shaped courses (only one true straightaway with the other curved to form a D shape).
Notable Speedways: Charlotte Motor Speedway (Concord, NC), Las Vegas Motor Speedway (Las Vegas, NV)
- Superspeedway – these are the grandest venues in all of stock car racing where the sport’s preeminent events are held, including NASCAR’s answer to the Super Bowl, the Daytona 500. Because of their length, these courses feature long straightaways where drivers can maximize speed and wider turns that are more accepting of higher speeds as well.
Notable Superspeedways: Daytona International Speedway (Daytona Beach, FL), Talladega Superspeedway (Talladega, AL), Indianapolis International Speedway (Speedway, IN)
The three road courses on the NASCAR Cup Series circuit are Sonoma Raceway (Sonoma, CA) which is 2.52 miles in length with 12 turns, Watkins Glen International (Watkins Glen, NY) which has eight turns spread out over a 2.45-mile long track, and The Roval at Charlotte Motor Speedway (Concord, NC) which is 2.28 miles long and has 17 turns.
As we are about to see, the length of the straightaways, the sharpness of the turns of the race course and the number of turns are primary factors in determining the specific brake characteristics that a NASCAR vehicle will have, and how those brakes will be used by the driver, on race day.
How the Race Track Influences the Car’s Brakes
There are several factors that affect a racing team’s decisions regarding the braking system components that are used at a particular race course, such as (1) the overall length of the track, (2) the length of the straightaways, (3) the number of turns and (4) the sharpness or width of those turns. These factors correlate to the type of track, e.g., short track, speedway, superspeedway, or road course.
Short Track and Road Course Braking
A NASCAR racing vehicle’s brakes experience their heaviest use during short track events. Not only are the brakes used with greater frequency, they are also used for longer durations. On short tracks, each turn is much sharper, and drivers typically apply the brakes the entire turn to maintain steering control and to set up their line on the track as they accelerate out of the turn into the straightaway.
To illustrate, a typical lap at the Martinsville Speedway is around 20 seconds, while the brakes are applied for six to seven seconds during each of the two turns according to Brembo. Thus, during each lap at this NASCAR Cup Series stop the brakes are applied for a total of 12 to 14 seconds during each 20-second lap. This amounts to the brakes being applied for roughly 60-70% of the time.
Braking relies upon friction, which in turn increases the temperature of brake components, particularly the rotor and pads. According to Brembo, during heavy braking (i.e., during turns), rotors can get as hot as 1800° F so it is critical that they do not overheat to the point of failing. Thicker rotors with enlarged ventilation channels along with beefed-up calipers are braking system features customized to short track events.
Braking systems for road courses are similar to those employed on short tracks because the turns are sharp, and the straightaways (which allow for the air cooling of braking components) are shorter. However, because road courses have numerous turns and thus more straightaway portions, the ventilation channels on the rotors are typically smaller because more air cooling can be harnessed.
Speedway Braking
Brakes are used more sparingly on speedways compared to short tracks, so racing teams will often use thinner, lighter rotors with smaller ventilation channels to go with medium-sized calipers. The key consideration here is balancing braking effectiveness against making the vehicle as light and aerodynamic as possible.
Superspeedway Braking
Racing vehicles can maintain average speeds approaching 200 miles per hour on superspeedways. Incredibly, brakes are not applied during a race except for slowing down under a caution flag or when making a pit stop. To prevent thermal shock and damage to the brakes, drivers will often step on the brake pedal to warm them up before actual braking, sometimes while also stepping on the accelerator.
Understandably, NASCAR racing teams will switch out braking components to their thinnest and lightest rotors, shoes, and calipers for events being held on superspeedway tracks where there is such a premium on maximizing aerodynamics and minimizing vehicle weight.
An incredible amount of pre-planning occurs before every NASCAR event. Strategies are formulated well before race day, and this includes deciding what particular brake components to use for the racetrack. In a sport where the margin of victory can be measured in tenths of a second, even something as seemingly minute as brake caliper weight can make a huge competitive difference.