Tech Report for XRAY X1'25 Car from ETS RD.1 - Apeldoorn

Last weekend, I attended the first round of the ETS 2025/2026 series at the beautiful Apeldoorn track in the Netherlands. This was my first race using foam tires, and I was curious about how the car would handle since I had no prior experience in this class.

I started with the setup from my teammates, but unfortunately, it didn’t work well for me. Due to bad weather, I had no time to test the car before the event, and the rainy conditions on Thursday meant I also had limited track time. I struggled with oversteering, traction rolling, and the car felt loose off-power. Despite trying adjustments based on what my teammates were doing to their cars, nothing seemed to help.

After struggling through the first three qualifiers, I decided to completely change the setup for the final round, as I had nothing to lose. Although I had no experience with the Formula class, I’m familiar with the X12’25 in 1/12 racing, which shares the same design concept as the X1’25. I applied the same setup changes I would use on my X12’25 when facing similar issues, and I was pleasantly surprised. Even though it was a different class and surface, the changes worked perfectly! Suddenly, my car was handling exactly how I wanted it. It became super easy to drive, there was no more traction rolling, and I gained significant cornering speed and forward traction.

Thanks to these changes, I made a huge improvement in the final, moving from 8th on the grid to finish 2nd overall. I won the first final and finished second in the second final, just behind my teammate David Ehrbar, who started from pole position.

Now that the car was handling perfectly, I’d like to share the key setup changes that made it so fast and competitive:

• Ball Diff to Gear Diff: Replaced the ball diff with a gear diff filled with 3K cSt oil. The gear diff provided amazing forward traction and improved cornering speed.
  
• Rear Setup: I changed the rear to a straight POD angle and used soft rear springs and side springs. Previously, I had stiffer springs to gain more steering, but these made the car too nervous. Eliminating the side spring preload made the car softer and more forgiving.
  
• Front Suspension: To eliminate traction rolling, I swapped the stiffer front springs for the new super-soft X1’25 spring (C=0.7). I also increased the front king pin oil for less responsiveness and added 2mm of droop to the front suspension. These changes helped with steering while avoiding traction rolling.
  
• Flex Setting: I used the stiffest flex setting for more stability, ensuring all side braces had screws connected and a stiff top deck.