What is Body Torsional Stiffness?

[AbelFitz]

Stiffness refers to the resistance of a vehicle body to elastic deformation. The stiffness of a vehicle body is certainly an area worth in-depth study, but currently, the domestic level in this field is still relatively weak. Various vehicle models still obtain values through benchmarking and testing to set their respective target values. Design values for static body torsional stiffness: Class A vehicles: The target value for body-in-white torsional stiffness is approximately ≥10,000 N·m/rad. Class B vehicles: The target value for body-in-white torsional stiffness is approximately 10,00013,000 N·m/rad. Class C vehicles including SUVs: The target value for body-in-white torsional stiffness is approximately ≥13,000 N·m/rad. Class D or higher: The target value for body-in-white torsional stiffness is approximately >13,000no upper limit N·m/rad (the upper limit depends on the vehicle model's target).

[OMaverick]

Body torsional stiffness refers to a vehicle's ability to resist deformation when cornering or driving on rough roads. Imagine wringing a towel - if the towel is soft and flimsy, it deforms easily when twisted, and the same principle applies to cars. A car with high stiffness is less prone to twisting during sharp turns, providing more stable handling. For example, when going over speed bumps, a low-stiffness car might creak and feel like the whole vehicle is wobbling; whereas a high-stiffness car behaves like a solid steel plate, with minimal body deformation as the tires pass over, delivering direct steering feedback. Modern automakers are striving to improve this metric by using hot-formed steel and laser welding, as stiffness directly impacts handling feel and safety - particularly during high-speed cornering where body distortion could compromise tire grip.

[MacLeila]

Simply put, it's about how rigid the chassis is, especially its torsional resistance when subjected to asymmetrical lateral compression. Those who've driven older cars know all too well about door frame rattles or chassis creaks—all symptoms of insufficient stiffness. Nowadays, this parameter is crucial when buying a car because it directly affects high-speed stability. In strong crosswinds or sharp turns, a non-distorting body maintains its trajectory. Some luxury cars achieve over 40,000 Nm/degree of torsional stiffness, making them noticeably quieter over bumps since the body doesn't deform to squeeze interior trim and create noise. Additionally, cars with high body stiffness offer better passive safety—the passenger compartment resists deformation during collisions, far outperforming outdated approaches that rely merely on adding sheet metal.

[Denise]

The torsional rigidity of a car. For example, when frequently driving over bumps and ruts on mountain roads, the car body may experience slight twisting. A car with high rigidity ensures all four wheels remain in contact with the ground, whereas a car with low rigidity may cause a tire to lift off and slip, resulting in sluggish handling. This mainly depends on the chassis design and materials. An all-aluminum body typically has 30% higher torsional rigidity than a steel one, but the cost doubles. For regular family cars, around 20,000 Nm/degree is sufficient, but performance cars generally aim for 30,000. Enthusiasts often install roll cages to enhance this.