NASCAR Stock Cars Weren’t Built For Road Courses, Which Is Why This Weekend’s Race On An F1 Circuit Is So Cool

Welcome to Austin, Texas for the first road course race of the NASCAR season at the beautiful Circuit of the Americas (COTA). There are few things in motor racing that are more fun to watch than stock cars on a road course for the simple reason that these cars absolutely were not built to to do it. The combination of not enough tire, not enough brakes, too much motor, too heavy and no downforce is absolutely glorious. Hustling a stock car around a road course is unlike anything else in road racing. There will be no steward’s office handing out 5-second penalties this weekend, just a full contact, gloves-off Texas-style brawl.

[Ed note: As an experiment, we’ve been watching this season’s NASCAR Xfinity Series races together in our Discord. We had Bozi around the first week and Alanis another week. During the conversation, a new name appeared: Aeden McHugh.

He’s not just one of Alanis’s many friends, he’s also the engineer for the #1 JR Motorsports car driven by Sam Mayer. Not only did Aeden provide race updates, he provided them from his pit box as the race was happening! Now he’s providing us with weekly track guides when he can. Join our Discord and come back tomorrow afternoon to talk about the race with NASCAR driver and podcaster Landon Cassill.]

Unlike most road racing series, NASCAR is incredibly lenient with track limits. The only place they are enforced at COTA is in the esses between Turns 3 and 7 where drivers are not allowed to place all 4 wheels inside of the curbing to shortcut the corner. Below is William Byron getting his qualifying time disallowed:

Speaking of curbs, one of the first things you will notice about NASCAR drivers on a road course is that they abuse the hell out of the curbs. These cars are hard to wrangle around a road course and the inside curbing is a useful tool for drivers to create rotation. When the rear wheels hit the inside curb, it acts to kick the back of the car around helping the driver rotate the car through the corner (here’s Kyle Larson at Sonoma, another road course).

Compared to other road racing series, stock cars have the longest braking zones. The high speeds combined with small brakes and lack of downforce means that braking zones are significantly longer, which is great for overtaking. Stock cars also tend to have significantly more body roll built into the setup compared to traditional road racing cars. It’s very common to see the inside front wheel lock up late in braking zones as the driver turns in and weight is pulled off of this tire.

In addition to lacking ABS, the Xfinity cars and Craftsman trucks also have solid rear axle housings and a truck arm rear suspension. Stock cars pitch forward heavily under braking meaning that the rear wheels are very lightly loaded. Because the rear wheels are connected to the engine and driveline, they will not lock under braking like the front tires will. Instead of lockup, drivers can experience “wheel hop” which is significantly worse. Under braking the rear tires are subjected to simultaneous opposing forces. The brakes and contact patch are trying to stop the wheels from rotating while the driveline’s trying to keep them rotating. If these forces become imbalanced the drive shaft and axles will begin to twist in a similar manner to a sway bar. When rear traction finally breaks, the drive line will snap back to its natural state and wheel hop begins. In this instant the driveline of the car is acting like an undamped torsion spring causing the rear wheels to literally hop up and down, making the vehicle impossible to control. See below

These Are NASCAR Stock Cars On An F1 Track

COTA was opened in 2012 as part of Formula 1’s attempt to grow its American audience. The construction of a stateside 3.42 mile (5.50km) circuit brought about the return of the USGP which had been on hiatus since it left Indianapolis in 2007. The circuit was designed by the FIA’s chief architect Hermann Tilke, who is perhaps infamous for his uninspired circuits (Sepang, Shanghai, Abu Dhabi, Turkey, Bahrain, India…). His first circuit in North America appears to be an amalgamation of his greatest hits from these circuits.

There are several characteristics that distinguish a Tilke-dromme, let’s see if we can identify them: Tight braking zones of similar radius? Yep, Turns 1, 11 and 12. A fast, high-speed kink? Right there in Turn 10. Double corner stadium section? You guessed it, take a look at Turns 13 to 16. A fast multi apex corner? You’re damn right. We have a carousel in Turns 17 and 18. He even added the double-low speed corners leading onto the Start/Finish straight for a little bit of extra spice.

If we were to take a lap around COTA, it would be like walking down Hermann Tilke’s Hollywood Boulevard. Turns 1 and 2 look a lot like Sepang’s Turns 9 and 10 if you laid them on a hill. At the Turn 10 kink you could forgive yourself for thinking of Sepang’s Turn 7, Turkey’s Turn 11, or India’s Turn 14. The stadium section in Sector 3 of Abu Dhabi’s Yas Marina Circuit looks almost identical to Turn’s 12 through 16 in Austin, Texas. Even the carousel is almost a carbon copy of Turkey’s quad-apex Turn 8, albeit in the opposite direction, and looks suspiciously similar to India’s Turn 10. Tilke does deserve credit for the originality with how he laid out the esses section of COTA. Unlike his usual high-speed left-right sections that he sprinkled into Bahrain, Abu Dhabi, China and Korea, Tilke broke from tradition and crafted a beautiful set of decreasing radius corners in emulation of Silverstone’s Maggotts-Becketts complex.

You will likely hear it mentioned multiple times on the broadcast this weekend how several sections of the racetrack have been repaved for this year. The circuit has been repaved piecemeal style over the years as it wears out and this year the areas due for repair were Turn 2, the braking zone and exit of Turns 11 and 12 and the exit of the carousel. Racetracks being repaved is nothing new or exciting under normal circumstances, but the reason for constant repaves at F1 circuits is fascinating. F1 cars put stresses on their circuits that are beyond any sort of normal circumstances. The downforce created by F1 cars is so great that the asphalt beneath them actually deforms and buckles in high-speed areas of the track. For example, under max braking at the end of a long straightaway, these cars will generate a force of about 5 tonnes (11,000 lbs) downward onto the racing surface. The cars will quickly break in the racing surface like a new pair of shoes, creating an indentation in braking zones and pulling up the asphalt in high-speed corners. For more information on this phenomenon, the Driver61 Youtube channel has a great breakdown of how racetrack deformation led to Sébastien Buemi’s iconic front suspension failure at Sepang during practice for the 2010 Chinese F1 Grand Prix.

 

In 2017 Formula 1 introduced a new set of regulations that saw the cars producing significantly more downforce than in years past. This has accelerated the rate at which racetracks degrade and has led to more frequent repaves and touch-ups. MotoGP rider Cal Crutchlow of Team LCR Honda had the following to say that year:

“The problem is that wherever we share a track with F1, the tracks are bumpy within a year […] with the downforce of these Formula 1 cars… Spielberg was a joke. It was worse than last year, and on a lot of the off-camber corners it was a lot worse, so it means the tarmac’s been pushed because of the cars.”

For all the criticism Tilke gets, it’s hard to ignore that Austin, Texas is a fantastic circuit that produces consistently great racing.

A Corner-by-Corner Breakdown Of COTA

Let’s take a lap onboard with Tyler Reddick as he qualifies his NASCAR Cup Series Toyota Camry and then talk about what makes this track so special (start at 4:29 if the video doesn’t do so immediately).

Turn 1 at COTA is probably its most recognizable. Following a 41m (133’) rise in the braking zone, Turn 1 features a blind apex at the top of the hill before drivers rush back down into the esses. The racetrack widens in the braking zone and then quickly funnels down on exit. This allows drivers to fan out 4 and 5 wide on a restart but forces them to shuffle, or force, their way back into line before Turn 2. While the wide entry is inviting to carry a ton of speed, missing the apex or running wide on exit will put drivers offline into Turn 2 and compromise their lap time through the esses all the way up until Turn 9.

In a switchback section, the rear end of a car acts sort of like a pendulum, slowly gaining momentum with each repeated change of direction. At most circuits where the esses are high speed, or increasing in radius to allow for acceleration, this pendulum effect can be combated with the throttle. As a driver accelerates, weight is transferred to the rear axle which will calm this pendulum effect and help to settle the car.

At COTA however, the esses are decreasing in radius, and therefore speed, as the sector progresses. From Reddick’s onboard camera, you can see him dabbing the brake pedal in between corners. If you pay close attention, you will notice that he is trying to slow the car once it has settled off the curbs and is heading mostly straight. This is because deceleration takes weight off the rear axle and allows that “pendulum” to swing more freely. If he applied brake pressure when turning into the next bend or before the car had settled it would cause the rear end to swing unpredictably.

The window between ess bends where the car is semi-stable is incredibly brief meaning that drivers play on a fine line when trying to hustle a car through this section. Being too aggressive with the curbs or mis-timing their braking will cause the rear of the car to step out and take them off course or into a spin. Not being aggressive enough is leaving precious lap time on the table. Watch below and you can see this pendulum effect take William Byron out of contention for the win on the last lap of the 2023 Xfinity Series race. He was trying to hustle through the esses to catch eventual winner AJ Allmendinger and stepped over that fine line.

As always in racing there are no free lunches. From a setup standpoint, stabilizing the rear of the car for the esses will cause understeer further around the lap in the stadium section of Turns 12-16. On the flip side, a car that is set up to corner well in the stadium section will feel very on edge from Turns 2-9.
The exit of the esses is one of the most crucial sections of the racetrack. From the exit of Turn 9, drivers will run wide open through the kink, down a hill and into a major overtaking zone in Turn 11. A small misstep in this area means either losing an opportunity to overtake the car ahead or being vulnerable to the car behind you.

Like a flat version of Turn 1, the entrance of Turn 11 is widened with an extra lane of asphalt to promote overtaking. Nailing this corner is crucial to the lap. Missing the apex of Turn 11 or running wide on exit will cause a driver to bleed time for the entire length of the 3,600’ (1,100m) back straightaway. Drivers will reach their highest speed of the lap, roughly 175 mph (280kmh), down the back straightaway before braking hard all the way down to about 35mph (55kmh) for the tight Turn 12 which begins the lowest-speed part of the lap in the stadium section. Turns 12 through 16 feature a series of tight, flat, double-apex switchbacks.

From a setup standpoint, the stadium section requires the exact opposite of what makes a car perform well in the esses and you will see drivers take a variety of approaches to try and get their car around these corners quickly. Ideally, in Turns 12 to 15 a driver would have a Max Verstappen Red Bull-esque car that’s very pointed on the front end with a rear that rotates quickly on corner entry. Unfortunately, this car would be borderline undriveable on the rest of the circuit. A driver must make a hard left-hand corner in Turn 12 before launching back across to the left-hand side of the race track to set up what is essentially a right-handed U-turn that leads directly into a left-handed U-turn. 

You will typically see drivers take two different lines in order to get their cars through this section. AJ Allmendinger is notorious for taking a wide, flowy approach to these corners. In doing so he uses little throttle and lets the car free roll along with a focus on having the highest minimum speed at all of his apexes. The key to his approach is in widening out the radius of the corners and letting the car free-roll at a higher speed. While this line is vulnerable to other drivers poking their nose to his inside on corner entry it does wonders for preserving the rear tires over a long run. Other drivers will try to get the cornering done as quickly as possible and then prioritize launching in a straight line off of Turn 12 and again from Turn 14 to 15. These drivers will use much less racetrack in between the apex curbs and place an emphasis on straight line acceleration between the corners. Looking below I attempted to roughly sketch out these approaches. In red is the Allmendinger line and in black is the more standard line. 

The carousel is another crucial section of the track for making lap time. The car is constantly on edge in this corner, and from the onboard cameras, you will hear drivers struggling to apply throttle while cornering at the limit of adhesion. Drivers will struggle to balance speed with corner radius all the way around the carousel. For most of the corner, drivers will be on the edge of a four-wheel slide as they try to use the throttle to help rotate the car around all four apexes. Watch below as Cole Custer tries to wrestle his Xfinity series Ford Mustang around this corner. 

The fourth apex is the most crucial to get right as pushing wide on exit of the carousel means the driver will be offline for the entrance of left-handed Turn 19. Nailing Turns 19 and 20 is the final critical section of the lap. Getting through these two left-handed corners well will set a driver up for an overtake down the Start/Finish straight into the hard braking zone of Turn 1.

Now that we know how to get around COTA, how does a NASCAR race play out on a road course? Well, like most things we’ve talked about it’s very different than a typical road race. Just like on the ovals, NASCAR races will have two stage breaks during each race where points are awarded. First place in a stage receives 10 points, second gets 9 points et cetera on down to 1 point for tenth place. Because the timing of the cautions is known before the race, strategy will be split into two distinct camps. Teams that believe they have a shot to contend for the win will do what’s called “flipping stages.”

NASCAR closes pit road two laps before the end of each stage and teams that are flipping will pit the lap before pit road is closed. The advantage of this is that they will cycle back to the front of the pack when the rest of the field pits under caution. The disadvantage for these teams is that they will forego any stage points that they could have received in exchange for track position. Conversely, teams that don’t believe they have a shot at the overall win will try to get as many stage points as possible. If they play their cards right they can earn more points than a top-finishing car with a so-so finish. A team that finishes 17th with two stage wins will earn as many points as a team that wins the race while getting zero stage points.

So, there it is. Circuit of the Americas. Road racing. Beautiful Ausin, Texas. The forecast calls for sunshine with a side of shitshow. Welcome to the party, y’all.