Today’s cars, even passenger cars, are designed and tested with tools and concepts that weren’t available just two decades ago. But even with these advances, automotive chassis design is fraught with compromise, as numerous design parameters—such as engine placement, cabin space, safety and material considerations, and target costs—play into what matters. which will be the final design. Few automotive enthusiasts or laymen will bother to understand forces, such as axial forces, shear forces, bending, torsion, angular deflection, and moments of inertia, when they set out to buy a car. Engineers care about these things, but as we said, design compromises force many designs to compromise in favor of balancing a car’s characteristics towards a certain percentile of the population.
Automakers know that the job of a car chassis is to hold vehicle components together while the car is in motion, all while loaded by forces (such as vertical and lateral loads) transferred to it by the suspension, at through the wheels. With standard OEM components like tires, shocks, springs, bushings and a stock drivetrain, any loads transferred to the chassis can be handled by the original design. The problem comes when you add wider stickers and/or rims, stiffer springs and/or shocks, stiffer bushings, and more power. Then you get unwanted chassis flex that affects the way your car handles. A big no no then. And when you’re talking about a car that’s been on the road for more than a few years, you can add metal fatigue to the equation.
The best solution for a really stiff chassis would be a carbon fiber tub or a chassis that has been seam welded with a roll cage added. Very impractical for a street/strip car enthusiast who has to juggle a budget or just wants a good enough solution. Insert the chassis clamps. Veterans will immediately be intimately familiar with the simplest of these, the strut brace. This, even today, is one of the first add-ons you buy when you put a chassis brace on your car. When cars were made with a separate ladder frame that the bodywork was attached to, there was also the subframe connector. Today, it has braces for the front and rear, undercarriage braces, fender braces, floor braces, and rear suspension braces to reinforce the mounting points of the rear arms.
Obviously the effect of these clamps will be to stiffen the chassis to the point where tuning the car’s handling will be a much more consistent affair. For those out on the track, these chassis braces may not result in dramatic time gains, but the improved confidence through better feel will improve consistency, which will affect how the driver rides. This then indirectly can lead to better times. For less-than-new cars, these clamps will, as we’ve said, stiffen the aging chassis to the point where the deck will be just as stiff, if not stiffer, than when new.