There is more to chassis braces than earning points at car shows... obtaining knowledge about them could very well make you a bit more versed about your performance upgrades. After all, knowledge is power!
The quest to increase chassis reinforcement is sought after by auto enthusiasts all over the globe. The most common modification done to achieve this goal is to use a metal brace that connects the two front strut towers together.
While this is a very common thing to do, many people will add a strut tower brace or any other body bracing without fully realizing what it does. In truth, chassis bracing is designed to give a sense of unity to the chassis, but this "unity" is fully realized only when you realize what the chassis brings to the performance aspect of your driving.
The true key to chassis reinforcement is to allow your suspension to work more efficiently, ultimately allowing you to get the most out of your tire.
Below, we'll be talking about how chassis reinforcement affects the suspension, steering, and ultimately the tire.
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Core Strength
If we look at the human structure, underneath the layers of muscle lies the skeleton. Having this core structure be strong is crucial during athletic activity, particularly during sports. Similarly for cars, having a rigid chassis provides the correct framework for high-performance driving.
While driving, the input from the road surface is sent from the tire to the suspension, ultimately making its way to the chassis; this feedback is sent to the driver through the seat and the steering. On the flip side, the input from the driver's steering is transmitted to the road in the opposite direction in this "closed loop". In order to provide accurate inputs from both sides, all components inside this closed loop need to function accurately.
Chassis Strength - Unity During Cornering
It is often said that the three key points for driver enjoyment and performance in vehicle control are the actions of acceleration, braking, and cornering. To experience confidence and enjoyment when pushing the car, it is vital that the three aforementioned items perform with immediacy and with accuracy.
Take a look at the above diagram, which displays a vehicle without adequate chassis bracing on the front shock towers. As mentioned in the previous article concerning the Motion Control Beam, a vehicle's chassis is designed from multiple spring elements which can cause body distortion and vibration. Due to inadequate torsional rigidity, the cornering forces have been transferred from the tire, into the suspension, and into the chassis. As the chassis has begun to act as the weakest link, the input from the tire is absorbed by the chassis, and distortion occurs. Due to the "closed loop" nature of this system, your steering input going to the road will also be affected.
The ultimate consequence of a disconnected chassis such as the one above is handed down to your tire. If the lateral rigidity of the body is insufficient during cornering, the gripping force from the tire will be absorbed by the chassis through the suspension, instead of being applied to the road. When coming from the opposite perspective of the driver, the action of turning the wheel does not see its full potential as the body distortion causes a delay in turn-in performance.
The more traction that is available to a tire, the worse this phenomenon gets. Furthermore, having an inadequately rigid chassis will not allow you to take full advantage of your tire. If you are looking to maximize your tire performance, or feel that the tire's performance is "veiled", it may be time to look into chassis reinforcement.
The above diagram displays a vehicle with bracing on two points- the shock tower and across the front cross member. By reinforcing the front cross member, the deformation of the pivot point under the suspension is suppressed.
One notable example where you will experience the benefit of a connected chassis is when you begin accelerating during the corner exit. In this situation, steering input, vehicle acceleration, and centrifugal cornering forces are all generated on a tire. For this scenario, minimizing body deflection, having smooth suspension movement and immediate turn-in response are key. The delay experienced from the initial turn-in not only hinders the car's reaction but also removes the feeling that the front wheels are connected to the steering wheel.
Too Much Body Rigidity
Enhanced body rigidity can provide benefits to your suspension and tire if the appropriate amount is used. However in some cases, adding increased bracing may have little to no effect if your suspension and tire are not up to par (correctly matched), and in some cases can even make your vehicle handle worse. If the tire you are using is inadequate, you may find that the grip threshold available will be much lower. In our previous scenarios, the chassis was the weakest link, but having adequate body rigidity, and suspension with an inadequate tire creates a new problem. It is important to find the correct balance in the "closed loop" in order to maximize your tire's performance.
Chassis bracing is available for a variety of vehicles and in different areas of chassis on our website from Quality & Engineered brands such as Autoexe, LegSport, and Toyota Technocraft. The next article will cover suspension and suspension tuning.