For nearly 20 years, we’ve met the high demands of our suspension customers by utilizing vertical dynamics test benches, including our KW 7-Post driving dynamics test bench. This allows us to develop a wide range of products, from vehicle-specific coilovers like the KW V3 Leveling (Street Comfort) to KW DDC plug-and-play coilovers (Street Performance), KW V3 Clubsport coilovers (Track Performance), and even KW Racing dampers for LMDh prototype sports cars.

Our vertical dynamics test bench, also known as the “KW driving dynamics test bench” or “KW 7-Post” by our specialist dealers, is instrumental in developing our Special-OE coilovers. These coilovers are increasingly being factory-installed in special edition and high-performance sports cars.

KW suspension development on the vertical dynamics test rig

This sets KW Automotive Group apart. No other coilover-focused suspension manufacturer has a system like our vertical dynamics test bench, and the resulting expertise is evident in every kilometer driven with our coilovers.

The coilover suspension kit, one of the most critical parts of a vehicle, connects everything from wheels and tires to the suspension, damping, stabilizers, axles, and steering. Before we delve deeper into our vertical dynamics test bench, let’s briefly refresh your knowledge of these suspension systems.

The myth of the do-it-all suspension persists. The reality? Suspensions are a carefully crafted compromise, designed to excel in specific areas. From original equipment manufacturers to aftermarket brands and motorsport teams, everyone strives to minimize this trade-off, tailoring suspensions for their target markets and applications.

Significant design and constructional differences exist between shock absorbers in racing cars and their counterparts in production vehicles. While both fulfill the critical functions of mitigating impact forces, managing vibrations, and ensuring vehicle stability through precise wheel control, the specific demands placed upon them necessitate distinct approaches.

To further optimize these characteristics and deliver bespoke suspension solutions, we leverage our state-of-the-art KW 7-post vertical dynamics test rig. This advanced rig allows us to directly analyze the intricate interplay between a vehicle’s elastokinematics, damper forces, spring rates, tire characteristics, and overall structure.

Through the utilization of our KW 7-post vertical dynamics test rig, we conduct comprehensive analyses of a vehicle’s elastokinematics, damper forces, spring rates, tire characteristics, and overall structure. This meticulous examination enables us to rapidly identify the optimal spring and damper configuration for a specific application. This includes tailoring the suspension to the unique demands of the vehicle itself, along with driver preferences and tire selection, while accounting for diverse weather conditions. By leveraging this data, we achieve the desired driving behavior with exceptional precision even before real-world testing commences. This significantly reduces the need for iterative adjustments during the development process, ultimately leading to the delivery of bespoke suspension solutions that perfectly match the application’s requirements.

While real-world testing remains essential for final validation, our innovative test bench delivers results remarkably close to the optimal setup. This translates to significantly expedited development cycles, ensuring we meet your needs efficiently.

Sporty suspension optimization prioritizes the minimization of wheel load fluctuations. This meticulous approach ensures optimal tire-to-road contact, maximizing frictional forces. Consequently, transient response during acceleration and braking is enhanced, while cornering capabilities are amplified through the generation of higher lateral forces. This translates directly to improved vehicle dynamics, enabling faster cornering speeds and ultimately contributing to reduced lap times.

Striking the perfect balance is the essence of damper and spring optimization. Vehicle dynamics engineers tirelessly work to achieve the ideal compromise: effectively mitigating vibrations without sacrificing crucial tire grip or precise body control due to excessive pitch and roll.

Mathematics and physics — the key to driving dynamics and ride comfort

For comprehensive data acquisition, the development vehicle or racing car undergoes meticulous instrumentation. This process involves the installation of various sensors, including accelerometers and spring travel linear potentiometers, onto the KW 7-post test bench.

This state-of-the-art facility features a high-strength base upon which four dynamically controlled hydraulic cylinders are meticulously positioned at each wheel location. These robust rams serve a dual purpose: integrated displacement sensors meticulously track their movement, while their design enables them to function as highly accurate wheel load scales.

Three additional hydraulic cylinders are strategically attached to the vehicle body, enabling the simulation of a broader range of forces encountered during real-world driving scenarios. In operation, each cylinder is precisely controlled to generate hydraulic pressure up to 230 bar within the hoses. This targeted actuation induces controlled vertical movement of the entire bodywork, allowing KW engineers to meticulously analyze resonant frequencies. These frequencies represent points at which the forced vibrations of the body are amplified, providing valuable insights for optimizing suspension performance.

During “stroke sine oscillation,” a carriage traverses a range of frequencies (0 to 20 Hertz) at a constant speed while maintaining a zero-point crossing phase. This precisely simulates the continuous vertical excitations a vehicle experiences while traveling over a road or racetrack. The analysis of this data, particularly in the absence of sufficient damping, exposes the critical role of dampers in maintaining vehicle composure. While the underlying technical details may possess inherent complexity, the practical implications are readily apparent. Through this rigorous testing procedure, chassis engineers gain invaluable insights into how even minor road imperfections, such as expansion joints or weather-induced surface variations, influence vehicle dynamics.

This enables engineers to precisely analyze the transient response of the suspension, specifically how efficiently the springs and dampers manage the resulting force impulse. By optimizing damping characteristics, the KW team ensures that the vehicle maintains a predictable and controllable line, even during high-speed cornering maneuvers.

The individual measurement of the frequency bands and resonances takes just 64 seconds. This is already enough for our experienced KW vehicle dynamics engineers to detect even the smallest suspension weaknesses from the data obtained. Key facts to always keep in mind: structural resonance frequencies, damping ratio, pitch behavior, body movement, dynamic vehicle level, and wheel load fluctuations.

Beyond measurements at constant speeds (75 mm/s, 150 mm/s, 200 mm/s, or 250 mm/s) simulating excitation speed, the test bench can also perform “track replay” to simulate specific racetracks or sectors. This allows for the replication of stresses encountered on real tracks, such as those experienced when driving through the Nürburgring Nordschleife’s Fuchsröhre.

However, to achieve this level of real-world simulation, the system must be operated in “7-post mode.” In this mode, the vehicle body is meticulously secured to the vertical dynamics test bench at two strategically positioned mounting points in the rear third and one at the front. These additional actuation points enable the precise simulation of a comprehensive range of aerodynamic forces, including lift, downforce, roll moments around the longitudinal axis, and pitching around the transverse axis.

While a current GT4 racing car or a road car such as a sports car like an “Audi RS 4 Avant Edition 25 Years” does not have a high aero load like a GT3 racing car such as a Porsche 911 GT3 R or an LMDh racing car such as the Lamborghini SC 63, the test bench for shock absorber and suspension development is used in vertical “4-post mode” without simulating an aero map.

For example, we even tune the various classic cars and young classics with our KW Classic V3 coilover suspension on our test bench for our KW Classic suspension applications — even for pure road cars.

Before our new suspensions graduate from prototypes to the test vehicles mounted on the driving dynamics test bench for final adjustments, they undergo a rigorous testing process. This includes dedicated damper test benches designed for endurance runs. These benches can simulate extreme conditions by subjecting the dampers to strokes of up to 7.5 meters per second and forces as high as 160 kilonewtons.

At KW, our commitment to quality extends beyond just KW coilover suspensions. Every single damper we manufacture at our Fichtenberg headquarters undergoes meticulous testing on a dedicated damper test bench. This rigorous process ensures 100% quality assurance for both KW and ST suspensions.

Thanks to our rigorous KW test bench development process, KW coilover suspensions like the KW V2 Street Comfort, KW V3, and KW V5 Clubsport are designed to deliver optimal performance right out of the box. This means you typically won’t need to book an appointment for additional adjustments on your car. For race car enthusiasts seeking a track-specific setup, our KW driving dynamics test bench is available for booking. Our experienced motorsport department can help you achieve the perfect configuration for your racing needs.

Photos KW, Archive, Words C. Schmidt