Technical and Race Report: 2024 World Championship Preparation - Part 1

The World Championship has always been, and will continue to be, the most important event for every company in the RC car industry. With XRAY being the reigning back-to-back World Champion—Bruno Coelho's victories in 2018 in South Africa and 2022 in Italy—we recognized that the 2024 World Championship would be particularly challenging. The competition would be fierce, making our pursuit of a third consecutive title more difficult. Therefore, we understood that we needed to be better prepared than ever.

Our journey to the World Championship in Bakersfield, USA, began in May with our attendance at the West Coast Invitiational, which served as an unofficial warm-up race. This was just the beginning of the outdoor season, and we had limited experience on asphalt at that time. We were unaware of how the trend towards new rubber tires would necessitate the use of aluminum chassis on asphalt—previously used only for carpet tracks. Although we had experience with aluminum chassis on high-traction tracks, such as the TITC, we generally preferred carbon fiber in those conditions. The trend shifted dramatically over the summer, positioning aluminum chassis as the primary choice, while carbon chassis became a backup option.

Initially, we focused on our carbon chassis and extended our stay for five additional days of testing after the race. Bruno recorded a fastest lap of 10.8 seconds during the event, and after a week of setup fine-tuning, we improved it to 10.6 seconds. Departing from LA, I felt confident that we had established a strong starting point for the World Championship. Our car performed well in the cool morning conditions and throughout the day, allowing us to find a stable setup for the high-traction conditions in the evening.

I was also pleased with our performance in the spec class, where Jan Ratheisky dominated the event, finishing strongly in third place alongside Mike Gee.

After summer concluded, we were informed about the World Championship Warm-Up Race held a month before the main event. As this race coincided with the 1/10 Off-Road European Championship, Bruno and several top drivers from competing teams came to test afterward. I attended the Warm-Up with Alexander Hagberg to gather setup information and simulate conditions similar to those expected at the World Championship. However, that week brought extremely hot weather, with daily temperatures exceeding 40 degrees Celsius. This resulted in different track conditions compared to the May race, and we anticipated that cooler temperatures would return one month later. Nevertheless, this experience allowed us to prepare for extreme heat, which may prove useful in future events.

As noted, aluminum chassis continued to be the trending choice during the summer season; we implemented it in several races characterized by medium to high traction conditions, as it provided enhanced stability, consistency, and cornering speed. Bakersfield was no exception; after a few runs comparing our Warm-up carbon setup with the aluminum setup from the European Championship, we quickly realized we needed to focus on the aluminum chassis and fine-tune it accordingly. The Warm-Up race proved successful, with Alex finishing strongly in second place, and our performance in the spec class also stood out, with Jan Ratheisky placing second, Shin Sawada third, Matus Benetin fourth, and Mike Gee rounding out the top five.

Following the Warm-Up, we dedicated five additional days to testing with the team. Extreme track conditions continued, with asphalt temperatures typically ranging from 45 to 60 degrees Celsius. By the end of testing, we felt confident, as the cars were performing brilliantly. We were motivated and excited for the Worlds, but I was also acutely aware that it would be a tight race where small mistakes could determine whether we would achieve our third consecutive title.

With the World Championship scheduled for November—traditionally the start of our carpet season—and having participated in three carpet touring races and the Masters of Foam with our new X12'25, which saw great success for Alex and the team, it became clear that we needed a short practice session in California to reacquaint ourselves with touring car asphalt racing.

We decided to practice at Exeter Raceway, a small track located about an hour and a half from the Worlds track in Bakersfield. Preliminary research revealed that Exeter had the same asphalt and track preparation as the Worlds track. Upon arrival, we were surprised by both the track size and its extraordinarily high traction, more reminiscent of racing on carpet than on asphalt. We were pleased that the track owner allowed us to practice and prepared the track for us. We were joined by several other teams taking advantage of this opportunity, allowing us to gauge our pace in these extreme conditions.

Technical and Race Report: 2024 World Championship Preparation - Part 2

I prepared three cars for Bruno Coelho, featuring a carbon chassis with the Warm-up setup, an aluminum chassis with the Warm-Up setup, and a third car with an experimental setup. After just a few laps, it was clear that we should set aside the carbon car and focus exclusively on the aluminum chassis. Many drivers expressed concerns about the excessive traction, noting that testing under such conditions would be pointless since we were unlikely to encounter such high traction at the Worlds. We had raced in Bakersfield twice before, and the traction had never reached these levels. However, I encouraged everyone not to give up, as we couldn't predict the track conditions at the Worlds, and it's always beneficial to collect data from every possible scenario for future reference.

For these reasons, we fully committed to finding the best setup for high traction. The main challenge arose in the sweeper at the end of the straight, where the car would spin and flip mid-corner. We needed to address issues with extreme oversteer, losing the rear of the car mid-corner, and traction roll in both slow and high-speed corners.

Given the traction levels reminiscent of high-traction carpet conditions, I adjusted the setup accordingly. To eliminate oversteer, I lowered the shocks to 1mm and changed the front springs from a range of 2.5-2.8 to 2.4-2.6. To prevent the rear from spinning, I adjusted the rear springs from 2.8 to 2.6-2.9, utilizing on-power springs to enhance stability in these conditions. I also installed a T-brace to improve the stability of the car, although this adjustment surprisingly led to more flips. However, the benefits of a more balanced car were significant, so I opted to keep the T-brace and sought alternative solutions for the traction roll.

I adjusted the front camber and caster, incorporating a carpet wave top deck, which positively impacted the car's handling. I raised the shims under the hubs from 0.5 to 1mm, as I typically do on carpet. With steering still notably high, I didn't adjust the toe gain and bump steer as I might usually do. However, I compensated for the downstop by lowering it by 0.4mm and reduced the shims above the hubs by 0.5mm to maintain the rest of the geometry. The car began to work exceptionally well, and by lowering the roll center through the removal of an additional 0.5mm shim above the hubs, I felt pleased with the car's performance.

In the evening, as traction increased further, the car was great to drive, except in the sweeper at the end of the straight, where mid-corner oversteering remained an issue. To address this, I added 15g to the bumper, adjusting the weight balance to 51% front and 49% rear. To further calm the car, we aimed to increase the hardness of the front shock oil. However, time constraints as darkness approached led me to grab PSS shocks with 450 oil from my box, as they felt significantly stiffer than our standard shocks (4x1.1 with 375 oil). I mounted these only on the front, and ultimately, the car's performance improved. The front was rolling less and maintained better roundness throughout the corner. This setup felt optimal for high-traction asphalt tracks, leading me to conclude our pre-Worlds tests as successful. We were all genuinely excited and ready for the return trip to Bakersfield for the 2024 World Championship.

Tuesday marked the first official day of the Worlds, primarily dedicated to registration. I was thrilled to reconnect with our US team, having not seen many of the drivers for quite some time. I was particularly excited to have Drew Ellis, our US team manager, present, as he consistently brings positive energy and humor to our pits, which everyone appreciates. Given our large team, which included both US and European drivers, we coordinated with Drew and Alex to ensure the best possible support for every XRAY driver, be they team drivers or customers. One of my main priorities at the races, aside from securing victories, is ensuring the happiness and satisfaction of every XRAY driver. It is personally crucial to me that each XRAY driver leaves the event feeling content with their performance.

Recognizing that the time schedule would be tight each day, with many runs and a limit on racing until 4:30 PM, we decided to organize daily team meetings after the races to share setup findings. This proved extremely successful, and I genuinely enjoyed our evening meetings, where we shared experiences, setup changes, and engaged in great conversations and laughter. Everyone had the opportunity to voice their questions and seek assistance. To expedite our communication and avoid delays, we created a Facebook group where every XRAY driver at the event could share their insights and support one another—a vital success factor for many drivers.

Technical and Race Report: 2024 World Championship Preparation - Part 3

The race commenced on Wednesday with five rounds of free practice. We anticipated very high traction right away, given the cold weather and track temperatures not exceeding 33 degrees. However, the reality was quite the opposite. Despite the club's efforts to clean the track before the event and applying traction compound in the morning, the track remained very slippery throughout the first day. Many drivers joked that we could only dream about the conditions we experienced at Exeter. Although I observed cars sliding around the track, I remained calm and committed to our plan of starting with the Worlds Warm-Up setup, with only a slight adjustment from 2 to 3 degrees of toe-in.

To my pleasant surprise, our drivers demonstrated impressive speed during the first round of practice compared to others. Our cars had significantly more forward traction and side bite, resulting in Bruno Coelho dominating the modified class and Jan excelling in the spec class. Given that I expected traction to improve and our cars were working well, I decided with Bruno to keep the setup unchanged and monitor the track's progression throughout the day. We maintained the same setup until the end of the day and I was very pleased with our team's performance.

Thursday's schedule included three rounds of controlled practice followed by the first round of qualifiers. We had another great start to the day, with Bruno winning the first two rounds of controlled practices, earning him the top seed for the qualifiers. As traction slowly increased, it became evident during the second controlled practice that traction levels were comparable to what we'd experienced in previous races on this track. However, the car became more edgy and difficult to handle. As it started to oversteer, I wanted to apply some of the setup knowledge we had gained in Exeter, but since the track conditions were not as extreme, I opted for minor adjustments.

I increased the front shock oil by 25cst and lowered the roll center by removing a 0.5mm shim from above the hubs on both the front and rear, which helped to make the car more stable and round. Bruno was fast from the middle to the end of each run, but he struggled to find pace at the beginning. Given that the Bakersfield track is quite small, with lap times around 10 seconds, and with ten cars on the track, it was critical to start quickly to avoid being pressured from behind. Therefore, I decided to soften the shock oil for the first qualifier, going from 400/375 to 375/350 oil. This adjustment proved to be effective as Bruno secured TQ in the first qualifier of the day.

On Friday, the schedule included four rounds of qualifiers. As the car began to approach the limits of traction rolling, we opted to lower the rear arm roll center by removing a 0.5mm shim and shifting the weight slightly toward the front. This was another successful adjustment; Bruno's pace improved, leading him to TQ in the second round of qualifiers. However, Bruno pointed out that while the car was very fast, it lacked roundness, making it necessary for him to drive from point to point, which hindered his ability to maneuver the sweepers effectively. To enhance the car's roundness, I decided to change the front anti-roll bar from 1.2 to 1.3. Unfortunately, this turned out to be an incorrect decision.

Although Bruno started the qualifier well with the car feeling rounder in the sweepers, the increased stiffness of the anti-roll bar limited the car's roll, resulting in the front inner wheels lifting during tight corners. This ultimately led to a traction roll on the straight, and as Bruno hit the throttle, the car flipped onto its roof.

I was disappointed with this wrong adjustment. I reverted to the 1.2 anti-roll bar at the front, aiming to make the car more manageable and rounded. I then decided to try another setup change that had worked well at Exeter by raising the hub height from 0.5 to 1mm.

Unfortunately, this also proved to be an incorrect move, as the car continued to lift in the corners and exhibited increased push.

Technical and Race Report: 2024 World Championship Preparation - Part 4

At that moment, there was still hope. With two wins and two losses, we had two qualifiers remaining. To ensure a solid strategy for the fifth qualifier—scheduled for late afternoon when traction conditions would be at their highest—I opted to revert to the setup we used for the second qualifier, where the car had performed the best up to that point. However, as the traction increased beyond my expectations, we faced yet another instance of traction roll. It was disheartening to see that after a strong start to the event, our car was fast but struggled with excessive traction.

The next morning, we had a short practice session before the final qualifier. Following our team meeting, we decided to implement additional setup changes collaboratively. Alex discovered a significant improvement by laying down the shocks and switching from progressive 2.5-2.8 springs in the front to linear 2.8 springs. He noted that his car was much easier to drive, although it still pushed too much. This insight was precisely what we needed, and I felt optimistic about our chances for the day.

As usual, we had a brief morning practice, and I was eager to see the effects of our changes. The first lap looked very promising, with Bruno Coelho achieving a lap time that was 0.2 seconds faster than the competition. However, during the second lap, he experienced traction roll—this was a shock, as I had anticipated improved stability.

With a short break between practice and the first final, I hurried to the pits to make comprehensive changes to the setup, aiming to keep alive any chance for TQ. At that moment, Bruno held the fastest qualifying time, meaning that if he won the last qualifier, he would secure overall TQ. I aimed to create a more forgiving car with reduced steering to mitigate traction roll. To achieve this, I changed the front springs to C2.4-2.7, which I typically use on carpet under high traction, to soften the car's initial response. I installed C2.6-2.9 springs in the rear for maximum stability and enhanced on-power push. Additionally, I added 10g of weight to the bumper to help prevent traction roll and lowered the servo horn from 19mm to 17mm to further reduce initial steering.

I decreased the ride height from 4.8mm in the front and 5mm in the rear to 4.6mm and 4.8mm, respectively. To maintain the same droop, I raised the downstop by 0.2mm. The car looked good at the start, and Bruno pushed hard for first place. However, as the run progressed, the car began generating more traction, becoming twitchy and again teetering on two wheels, resulting in traction roll. At that moment, I felt a wave of disappointment and frustration. We had dominated the first two days of the event but lost our momentum as track conditions shifted significantly.