Convertibles haven’t raced at Martinsville since the 1950s, when NASCAR went to a closed cockpit concept that would have the ability to run on a variety of tracks. But a temporary assignment for Martinsville president Clay Campbell led to an idea where NASCAR and IMSA leadership agreed to put Mazda MX-5 Cup cars on an oval. And so, several decades later, the powers that be were putting convertibles back on track, and that track happened to be Martinsville.
The initial test in 2023, brought NASCAR veterans Dale Earnhardt Jr. and Bobby Labonte, along with some of the MX-5 Cup regulars for the day where the group demonstrated that there was potential in the idea of putting the MX-5 on an oval. Thanks to the FIA-approved cage and an interior with things like arm restraints specifically built for cars to race without a roof, the MX-5 Cup series cars were already prepped for racing — at least to run events at road courses alongside the top level IMSA sportscar series. To take on an oval, these cars just needed a setup conducive to running on one.
The Initial Setup: From Road Course Racer to Oval Contender
For reference, the MX-5 Cup car weighs around 2,400 pounds and is closely based on its production counterpart, using the same 4-cylinder engine. The production-based bodywork is often the same as what you might find on the lot at your local Mazda dealership. Whereas, the cars that typically run at Martinsville are purpose-built tube frame machines weighing around 3,100 pounds with a silhouette body, often built to be asymmetrical, which means that bodywork and sometimes even suspension is unequal from the left side of the car to the right. To get a stock, production-based car to be ready to run on an oval will require a wide range of adjustment while using production-based components on a car that is built to be symmetrical, as well as lighter.
Todd Flis and his group at Flis Performance were up for taking on that challenge. Their expertise turning hundreds of production MX-5s into race cars and maintaining them would be crucial to get these MX-5 Cup cars oval-ready. Using the data from that first test in 2023, they began creating a baseline setup for the MX-5 cars. Crunching the numbers, the adjustments needed were minimal, landing on a suspension setup that could be done completely with the MX-5’s spec parts.
Now, road course cars, like the MX-5, will run negative camber on both sides of the car since they have to turn left and right. Yet, cars set up for ovals will typically run positive camber on the left and negative camber on the right since they are only turning left. This usually requires specialized pieces to be made or fitted, but it turns out, based on the setup sheet that Flis shared with me, they were able to set up the cars in that direction without it. While the setup was not as aggressive as something that you might see during a NASCAR weekend with multiple degrees of camber and extremely low tire pressures, the MX-5 Cup cars had about a quarter degree of positive camber on the left and around 2.5 degrees of negative camber on the right.
These changes were supplemented by dropping the ride height on the left side about an inch lower than the right side, and running ten pounds less of tire pressure on the left than the right. The oval setup was completed with some toe changes and running 300 pound springs on the left, along with 500 pound springs on the right on the spec Multimatic DSSV shocks.
Flis’ MX-5 setup was finally put to the test following the IMSA race weekend at VIRgina International Raceway. With Martinsville just an hour away, it was a short trip for teams to haul their cars and people over for some laps.
Test Day
It was a hot August day when the MX-5 Cup teams arrived for the big test, and it didn't take long before cars were putting down lap times in the 23-second range thanks to Flis’ initial setup. Of course, then it was time to do more tweaking, and team owner and driver Chad McCumbee of McCumbee McAleer Racing (MMR), started to play with the setups to find more speed.
“I just wanted to test and be the test dummy, and work on totally different setups and try everything we could possibly try,” McCumbee explained. "We found some stuff that could have some merit, but we also found that our baseline that we had on all these other cars was really good.”
McCumbee has a history of competing in almost every national NASCAR and IMSA series, and is a regular on the Cars Tour (which competes on short ovals around the Southeast U.S.), making him a perfect fit for taking on this type of exercise.
One thing McCumbee paid mind to while making adjustments and throughout testing were the tires. The MX-5 Cup cars were running on the same Michelin tires that they had used at VIR over the weekend, which were specifically designed to run on road courses—not ovals. But the worn Michelin road-course tires performed flawlessly, according to McCumbee. Even testing on older used tires for most of the day, he had yet to find one tire with any type of imperfection, which is important to note as oval tires typically come in a range of compounds, and things like heat and corner loads can reveal imperfections during a long test like this one.
Putting his cars to the test were Cars Tour regulars Brandon Pierce and Landen Lewis. McCumbee invited the two as a way to step outside of their comfort zone, and lend their expertise. Lewis has won in ARCA and had just come off a win at the Cars Tour Late Model Stock race at Wake County Speedway, while Pierce, was a fellow Cars Tour competitor as well as Late Model winner with experience on dirt tracks.
“This is my first time ever driving one of these types of cars. Anything with headlights,” Lewis said. “I looked in my mirror on one lap and I had a headlight on and I’m like oh, I got headlights! I can turn these on!”
Lewis was first to get into the car. He had experience on road courses with stock cars and had driven smaller cars with sequential gearboxes, but had never raced something like the MX-5. Because of the lighter weight of the MX-5, he was able to brake much deeper into the corners. It wasn't long after nailing that new braking line that he was offering suspension adjustment suggestions to the MMR crew which then substantially improved Lewis’ lap times through the rest of the session.
Pierce was next up to take the MX-5 on track. With a background in dirt racing and go karts, and his most recent experience being in asphalt late models, he too, adjusted to the new car, then quickly began posting competitive lap times.
“For us short track guys, wedge is probably the biggest thing for us,” Pierce said. “That's a similarity that they were able to do as an adjustment that we like most and outside of that just some rebound changes with the shocks and air pressure. That’s really all that you can do to these things and that’s pretty cool. I like how they react even to those minute changes. For us in late models, if you do something like that you might not even see a change.”
Wedge is a measurement of the cross-weight of the car which is a measurement where the weight of the right front and left rear corners of the car is divided by the total weight. Flis issued a recommended cross weight of 47.6% and teams could adjust that up or down to adapt the car to the track. In addition to that adjustment, the Multimatic DSSV shocks that are installed on the MX-5 offer rebound and compression adjustments. Lewis found that he could fine-tune the car by changing the rebound settings on specific corners.
Also joining the test-day session was ARCA and Whelen Modified Tour driver Andy Jankowiak. Modified Tour cars, as a note, are tube frame open wheel race cars and quite a bit different from the MX-5. But like most drivers, Jankowiak races anything he can get his hands on. He found he was able to make speed quickly and suggest adjustments to the MX-5, thanks to his experience racing modifieds at Martinsville and racing lighter weight cars in the Northeast.
“We were working on some shock stuff,” Jankowiak said. “And they actually have a regular driver that was here. He started the day and then I worked with the car all day. [...] He actually jumped in when I was done and seemed very impressed with the way that the handling improved. That’s always encouraging to hear and we were pretty similar on the stopwatch there. I think we were both within a tenth. That’s encouraging for me seeing that I can pace with the guys that do this all the time.”
Next Up: Race Day
The 100-lap Mazda MX-5 Cup exhibition race at Martinsville will be paired with the 200-lap season finale of the NASCAR Whelen Modified Tour on Saturday October 26th. For a driver like Jankowiak, who already races in the Modified Tour, and now has experience behind the wheel of the MX-5 at Martinsville, racing both would be an easy bet.
“I’m very lucky to have a good friend with Teddy Marsh and he’s going to work really hard to put a deal together to be able to run this Mazda race,” Jankowiak said. “Then my car owner in the Whelen Modified Tour is Steve, [...] I never know what he’s going to do but you know we’ll wait and see what’s going on.”
A fun drive will be the convincing factor for any driver not in the MX-5 series to find a ride for the October race. No matter who ends up behind the wheel, these MX-5s on an oval will make for an exciting watch for fans and offer something quite different than what most have witnessed at Martinsville.
