We recently spoke with colleagues from the trade magazine “asp Auto Service Praxis” and explained what to look for with coilover suspensions. The interview was published in issue 3/2025 and is also available online in German.

Our head of R&D, Thomas Wurst, answered the questions of the asp editor. We are publishing the full version of the interview with our colleague on our KW blog.

asp: KW automotive offers three different suspension brands. What are the characteristics and differences between the suspensions from KW, ST, and ap? Which one is recommended for which application, and what are their specific advantages?

With our suspension brands KW suspensions, ST suspensions, and ap Sportfahrwerke, we at KW automotive offer an extensive range of completely different coilover suspensions with various technologies. From the beginning, we have focused on ensuring that our suspensions significantly enhance driving pleasure while also meeting desires such as maximum lowering within the legal regulations and technical conditions of the vehicle; after all, all our street applications come with a parts certificate.

In recent years, we have introduced numerous damper technologies and offer one of the largest suspension programs in our segment. Whether someone is looking for a custom suspension solution for a modern electric car, a classic vintage car, or a super sports car, we have the solution for them. In addition to manually adjustable suspensions, which can be tuned in the high-speed and low-speed ranges of compression and rebound forces, we also offer semi-active coilover suspensions with electronically controlled valves.

For some vehicle models, such as the BMW 3 Series (F30), we offer various suspensions from all our KW product groups: “Street Comfort,” “Street Performance,” and “Track Performance.” This ensures that we can provide each of our customers with the perfect coilover suspension for their needs. Each of these categories includes suspensions with different functions and corresponding areas of application.

Someone looking for a suspension system for track days will find that KW offers a range of options in their Track Performance section. This includes various Clubsport suspension systems with certification and pure motorsport suspension systems. These motorsport suspension systems are also developed and manufactured as homologated racing applications for the customer racing programs of various automobile manufacturers.

The Street Performance category includes our well-known KW V1 to KW V5 and KW DDC plug&play coilover kits. The KW V1 is individually height-adjustable within the TÜV-approved range. The KW V2 coilover kit also features an adjustable rebound stage, which allows for further adjustment of the handling.

With the KW V3 coilover suspension, both the rebound and compression damping can be adjusted separately. This allows drivers to tailor the suspension even more precisely to their individual needs and vehicle characteristics, for example, by perfectly adjusting the suspension to the wheel/tire combination fitted. The KW V4 coilover suspension is ideal for anyone who wants to independently adjust the high-speed and low-speed compression damping when tuning the damper response.

The KW V5 coilover suspension, on the other hand, is manufactured with solid piston dampers and currently offers maximum customization options (separately adjustable high-speed and low-speed rebound damping as well as high-speed and low-speed compression damping). Our adaptive DDC plug & play coilover suspension kits are also increasingly in demand. These are compatible with the standard suspension control systems of current vehicles and are regulated by the standard electronics.

In the “Street Comfort” section, we offer suspension systems such as our KW V2 Comfort, which allows for subtle lowering and features an adjustable rebound valve for further customization. With the KW V3 Leveling suspension, comfort-oriented customers can enjoy a slight lowering and individually adjust the dampers in the compression and rebound stages to suit their needs.

In addition, the KW, ST, and ap coilover kits also differ in the materials used, certain individual parts, and the technologies employed. We manufacture the struts for KW coilover kits primarily from stainless steel, while black steel alloys are used for the ST and ap kits.

We have now introduced four different coilover suspension variants for our ST suspensions brand. However, these do not offer such a wide range of functions and applications as the KW coilover suspension kits and can only be adjusted manually in terms of damper characteristics. The coilovers from ap Sportfahrwerke do not have adjustable dampers. These coilovers allow for purely stepless lowering.

asp: What are the general advantages of a coilover suspension kit?

The general advantage is that high-quality coilover suspension kits improve driving dynamics and safety. They also offer continuous lowering, allowing the ground clearance to be adjusted manually within a specified range. This makes it possible to change the vehicle height perfectly to the mounted wheel/tire combination ratio. Coilover suspension systems also allow the wheel load to be adjusted.

Our coilover kits, with matching springs, dampers, and elastomer spring elements such as bump stops and dust protection, are always developed specifically for each vehicle and delivered as a complete unit. During installation, only the standard bearings need to be mounted. Many coilover kits also offer the option of adjusting the dampers in various parameters. The old prejudices against coilover kits are long gone. As a development partner, we have been supplying our suspension technologies to selected automobile manufacturers for many years, who use our semi-active or manually adjustable suspension kits in special models from the factory or offer them as optional accessories.

asp: What needs to be considered when installing a coilover suspension kit?

It is always essential to follow the installation instructions provided by both the suspension and car manufacturers, as a car suspension is a safety-related component. Experienced automotive technicians, mechanics, and master craftsmen will find that consulting the installation instructions makes their daily work much easier. Sometimes, components from the original series production suspension must continue to be used when installing a coilover suspension kit. Struts and shock absorbers should never be installed in a tense position.

Even when changing the vehicle height, we recommend loosening the mounting bolts on the chassis from the wishbone and only tightening them again to the required torque once they are in their design position. If expansion bolts have been used, always ensure that they are replaced in accordance with the vehicle manufacturer’s specifications.

Never use an impact wrench on the coilover suspension or other suspension parts, and never use pliers on the piston rod. Always use the correct torque settings during installation. We recommend using the values specified by the vehicle manufacturer. Once a suspension has been installed, the axle geometry must be checked and the track remeasured. This also applies when changing the vehicle’s height.

asp: Does the mechanic require special tools or equipment for installation?

Every auto repair shop has all the tools you need, such as spring compressors, wheel alignment equipment, and similar items, to install a coilover suspension. However, depending on the type of vehicle, you might need some special tools. Always use the right tools for the job. We’ve assembled a 30-piece KW special tool kit for our retail partners.

asp: What effect does adjusting the compression and rebound settings have?

The KW and ST coilover kits, which can be adjusted in terms of damping characteristics, are always supplied with a vehicle-specific, pre-set damper setup. If you want a firmer or slightly more comfortable ride, you can adjust this in just a few simple steps using the adjustable compression and rebound damping valves.

Simply put, the compression stage influences the compression, and the rebound stage influences the rebound. Higher compression stage forces or a harder compression stage on the front axle ensure even more direct steering. The car becomes more precise in steering, and the handling is more aggressive. A softer compression stage, on the other hand, makes the steering behavior much more docile. Higher compression forces counteract oversteer on the rear axle, making the vehicle more stable when changing direction. A softer setting allows the rear to steer much more freely.

A higher rebound stage makes handling on the front axle even more direct, although ride comfort may be slightly reduced. Low rebound stage forces increase ride comfort at slow speeds, while higher rebound stage forces provide better feedback in terms of handling.

asp: How do you correctly adjust a coilover suspension and determine the correct and permissible height?

When adjusting the suspension, it is important to ensure that both axles are adjusted to match each other. Different coilover suspension systems can adjust the compression and rebound valves in the high-speed and low-speed ranges. Fast piston rod movements, i.e., the high-speed range, are always transmitted to the suspension via the road. Slow piston rod movements, i.e., the low-speed range, tend to occur when the vehicle accelerates, brakes, and steers.

To determine the correct height for lowering, it is always helpful to consult the installation instructions and the parts certificate, where the various dimensions are listed. When installing the suspension, the StVZO regulations regarding the height of the lighting equipment, the license plate mounting height, and the ground clearance must also be observed. Installation partners should always check that the wheels have sufficient clearance so that the tires do not rub against the suspension, the inner wheel arch liner, or the fender edge when the suspension is compressed.

The Straßenverkehrs-Zulassungs-Ordnung is a set of rules in Germany that govern the technical requirements for vehicles to be allowed on public roads. These regulations cover various aspects of vehicle safety, construction, and operation.  To comply with StVZO regulations, vehicle owners and modification shops must ensure that any changes or installations meet the specified standards. This often involves consulting the parts certificate and installation instructions provided by manufacturers.

We already take all these points into account during the development of our suspension systems, as our coilover kits come with a parts certificate. When adjusting the ride height, we recommend selecting the same thread setting for the right and left sides.

asp: How is the chassis measured correctly after installation?

After mounting the coilover suspension kit, adjusting the axle geometry is essential. Use the axle geometry values specified by the vehicle manufacturer. If the vehicle height is adjusted later, remeasure the axles. A modern wheel alignment system offers the easiest and most convenient way to achieve this.

asp: Are the target groups only “sporty” drivers?

For several years, the core message of our KW suspensions brand has been that we have the right suspension for every requirement. Our focus has expanded beyond sporty drivers. With our KW V3 Leveling and KW V2 Comfort coilover suspensions, we are targeting customers seeking a very comfort-oriented driving experience.

However, comfort is not always just about driving performance; drivers also appreciate being able to negotiate speed bumps or steep underground garage ramps without bottoming out. This is why we also offer hydraulic lift systems.

asp: How extensive is the market coverage with KW suspension systems or across all three suspension brands?

Our core business involves the development and manufacture of manually and adaptively adjustable coilover suspension kits, other suspension components for the aftermarket, and an accessories range for various automotive manufacturers. We are one of the largest players in our segment and the market leader in coilover suspension kits.

We offer the widest range of applications with our KW suspensions brand. What makes this special is that we manufacture our KW coilover kits to order. Put simply, when someone orders a coilover kit from one of our specialist retail partners or directly from us, we start production in-house. Our product range includes over 2,350 vehicle applications for coilover kits, and we now have over 27,000 different suspension applications listed, excluding our suspensions for industrial partners.

asp: Does KW also offer training courses for interested workshops?

We have developed a comprehensive training concept for our specialist retail partners that goes far beyond typical product training. It includes extensive training courses, ranging from chassis tuning and wheel alignment to driver training. There are various levels, culminating in the status of authorized KW Track Performance Partner, specializing in our clubsport applications.

By the way, in the third episode of our YouTube series Ask the Expert, our development workshop team leader Markus Wahle and product manager Sascha Daucher answer your questions about the development of our well-known KW coilover kits.