In modern 1/10 off-road racing, stiffness and durability was once the primary goal. Stronger, thicker, and more rigid parts were seen as the key to consistency and precision. While stiffness still plays an important role, today’s high-grip tracks have revealed its limits. A car that is too stiff can struggle to generate forward bite, feel harsh over bumps/jumps, and become unforgiving when switching directions. Instead of absorbing energy, the car deflects it, which often leads to lost grip and inconsistent lap times.
As tracks have become smoother and traction levels have increased, the demands placed on the chassis and suspension have changed. Cars are now required to generate lap times mechanically rather than relying solely on tire choice or raw talent. This has pushed designers and racers alike to look beyond stiffness alone and focus on how the car behaves dynamically under load. Understanding where and how a car flexes has become just as important as spring rates, shock oil, or geometry changes.
This is where controlled flex becomes critical. Properly engineered flex allows the chassis and suspension to work with the track rather than against it. When flex is intentional and predictable, it improves mechanical grip, helps the car settle through bumps and landings, and stabilizes behavior through the pitch axis without sacrificing response. The key distinction is that not all flex is beneficial, uncontrolled or accidental flex caused by certain geometry or weak mounting points introduces inconsistency and unwanted issues while driving.
At Factory Foote, flex is treated as a tuning tool. On our 2WD cars, we have run soft side guards for many years, as they increase overall drivability and forgiveness. This is a clear example of when additional flex can be advantageous, especially on high grip or technical layouts. However, flex must always be evaluated in context, as its location and direction are just as important as its amount.
On the B84, particularly in the rear of the car, there is a significant amount of side to side flex. This is likely due to the narrowing of the rear pivots and the D block no longer being mounted directly to the chassis. While this design can offer benefits in certain conditions, it can also introduce excessive lateral compliance in the rear. In some cases, the rear of the car can feel disconnected from the rest of the chassis, making the car harder to read and reducing confidence when pushing the limits.
This led us to develop an immediate solution. A two piece stiffener that mounts from the side guards to the front of the rear gearbox, limiting side to side flex in the rear of the car. By tying the rear end back into the chassis, this change helps the rear suspension work more in unison with the rest of the car. The goal is not to eliminate flex entirely, but to control it in a way that restores predictability and makes setup changes more meaningful.
This stiffener is just one step in an ongoing development process. As we continue to test and refine the B84 platform, we are evaluating additional ways to improve balance, consistency, and tunability without sacrificing speed. Every change is driven by on track feedback and real world testing, with the same philosophy in mind: Go faster.
