BMW Group University The Ultimate Driving Machine Product News No. 27/2014 December 2014 BMW CHASSIS SYSTEMS: DYNAMIC OR COMFORTABLE WHICHEVER THE CUSTOMER PREFERS. BMW vehicles are renowned for their extraordinary dynamic performance. This has been confirmed time and again in group tests by international media and confirmed through customer testimonials. The advanced chassis designs of the various model series, as well as their precise fine-tuning, play a major role in this. In addition to the advanced technology of its standard chassis, BMW is providing customers with an extremely comprehensive range of options enabling them to configure their vehicle s driving characteristics in line with their personal requirements. Thus, a BMW 3 Series driver opting for an Adaptive M suspension can enjoy almost all the comfort of a luxury sedan or calibrate the suspension to mimic the dynamic, stiff set-up of a sports car. Today s Product News will tell you what makes the BMW chassis and steering systems so unique, and what specific benefits they provide to your customers. At a glance: All BMW models deliver special dynamic performance: this is due to advanced chassis engineering and the thorough fine-tuning work that BMW engineers apply even to their models standard chassis. BMW chassis systems are extremely dynamic. Even the standard systems are painstakingly fine-tuned. Satisfying contradictory goals: dynamism vs. comfort. Standard chassis set-up involves trade-offs. Range of variable suspension and steering systems. Model-specific set-up defines vehicle character. Adaptive chassis systems as a perfect solution to conflicting objectives. Maximum variety of set-ups from very comfortable to very sports car-like. Character-defining: suspension, damping and steering. Manufacturers are increasingly trying to position their vehicles in the dynamic segment of the market. This means that they are also trying to provide a corresponding driving experience. BMW has often acted as a role model for such carmakers, because the company creates very responsive and agile vehicles whose characteristics have delivered the brand s promise of The Ultimate Driving Machine time and time again. The chassis not only defines the character of a model, it can also shape the character of an entire brand as in the case of BMW. In addition to the drivetrain, an advanced chassis is the main factor contributing to superior performance and handling. Everyday driving poses diverse challenges, and an outstanding car has to satisfy conflicting aims: sportiness and agility on the one hand, and ride comfort on the other. The steering and suspension/damper fine-tuning are essential elements that define a vehicle s character. The design of these components determines whether the vehicle will tend towards the comfortable or the sporty end of the spectrum.
Chassis systems for perfect suspension component adjustment. To help customers avoid an (unsatisfactory) compromise between the above requirements, BMW is offering various chassis control systems which can be used to select the optimal settings for each driving situation. The prerequisite, however, remains a perfectly calibrated basic chassis. Chassis control systems then provide perfect fine-tuning options which leaves drivers safe in the knowledge that their cars will always move exactly how they expect them to move according to the selected driving mode. The fine-tuning of the chassis, i.e. the precise calibration of all components, is a high priority during the development of all BMW models. Superior engineering content and precise fine-tuning. It should be noted that it is not just the versatile hardware itself, but first and foremost the sophisticated and precise fine-tuning of the system that enables a superior result. BMW invests a lot of effort into finding and testing the perfect set-up. Given that the various chassis components, as well as the suspension/damping and steering, are all dependent on each other, they have to work in perfect harmony at all times. The excellent handling of the BMW X6, which, despite its higher weight, handles almost like a sports car, is the result of the extensive chassis expertise of BMW engineers. In addition to variable steering systems, electronically controlled dampers provide the basis for almost all BMW chassis control systems. They enable drivers to adjust their stiffness automatically depending on the driving situation or according to the driver s wishes, and are either the main or one of the central components of the chassis systems described below. Dynamic Damper Control: for a versatile chassis. Dynamic Damper Control enables drivers to adjust the stiffness of the shock absorbers, matching the damping characteristics to their preferences in the situation at hand: superior ride comfort, or a very sporty set-up. But even without driver input, these dampers are capable of constantly adjusting their actions to terrain, vehicle load, and personal driving style, and reduce irritating body roll to a minimum. Variable damper set-ups enable either a very comfort-focused or a sporting and dynamic driving experience, according to the individual situation or the driver s personal preferences. While driving, sensors constantly collect data and adjust the shock absorber valves of the Dynamic Damper Control to be in line with the driving situation and road surface. The sensors provide data on wheel, lateral and longitudinal acceleration, vehicle speed and steering wheel position to an electronic control unit which then adjusts damper response accordingly. This is done separately for each wheel, which ensures optimal handling at all times. The default COMFORT setting (and COMFORT+ for the BMW 5 Series and 6 Series) makes for smooth and comfortable driving characteristics. The SPORT mode (and SPORT+ mode for the BMW 5 Series and 6 Series) uses a stiffer damping set-up which makes for a more immediate and sporting driving experience. Each mode is activated via the Driving Dynamics Control in the center console. The Driving Dynamics Control is included as standard with all BMW models. In its basic version, it only influences accelerator response, automatic transmission characteristics and steering. Depending on the model series and on whether a BMW is fitted with the optional Adaptive M suspension and the Adaptive Drive option, it also affects the damping characteristics of the Dynamic Damper Control. The benefits of Dynamic Damper Control: Dynamic or comfortable driving characteristics at the touch of a button. Optimal oscillation/vibration characteristics in line with vehicle load. Reduction of unwelcome squat and dive. Shorter braking distances in the event of a hard stop (dampers keep the vehicle horizontal, all wheels maintain optimal traction). The Driving Dynamics Control influences accelerator response, the automatic transmission set-up and the steering. In conjunction with the optional Adaptive M suspension it also adjusts the damper characteristics to either produce outstanding ride comfort or enable very sporty and dynamic driving. (Available as an option for the BMW 5 Series, BMW 6 Series, BMW X3 and BMW X4.)
Adaptive M suspension: enhanced dynamism and comfort. The optional Adaptive M suspension builds on the technology of the Dynamic Damper Control and further enhances the vehicle s dynamic abilities. The chassis is lowered by.4 inches, which provides a visual clue without sacrificing comfort. The benefits of the Adaptive M suspension: Adaptive M suspension: Even on the most challenging surfaces, the chassis remains good-natured and body roll is limited even when the car is fully loaded. The BMW chassis engineers have done an outstanding job. (Auto Zeitung, 10/9/2014) Pronounced dynamic ability or extremely high cruising comfort at the touch of a button. Optimal traction and stability. Dynamic driving right up to the limits. More direct steering and drivetrain response. Chassis lowered by.4 inches for a sporty appearance. (Available as an option for the BMW 1 Series, BMW 2 Series Coupe/Convertible, BMW 3 Series, BMW 4 Series, BMW Z4, BMW X5 and BMW X6.) Active Roll Stabilization: stabilizers reduce body roll in corners. The Active Roll Stabilization chassis control system uses stabilizers on both axles to reduce body roll to a minimum in bends and when swerving quickly to avoid an obstacle. In addition, the distribution of roll between the front and rear axles results in agile and safe handling. The benefits: precise steering response, superior agility and significantly improved ride comfort. The active stabilizers continuously adapt to the driving situation and adjust the vehicle s steering behavior. Thus, when driving in a straight line, Active Roll Stabilization responds sensitively, separates the two halves of each stabilizer set and thus provides the best possible damping comfort, which also benefits the rear passengers. When driving through bends or swerving to avoid an obstacle, on the other hand, the system uses a sporty stabilizer set-up to prevent or minimize body roll depending on lateral acceleration. The distribution of body roll between the front and rear axles also defuses critical situations while increasing driving pleasure. Thus, Active Roll Stabilization provides superior agility and stability in all situations, as well as excellent suspension comfort and enhanced safety. Optional Active Roll Stabilization and Adaptive Drive are systems which use active stabilizers to reduce body roll to a minimum in bends, or when swerving to avoid an obstacle (top). Without this technology, body roll is much more pronounced in bends (bottom). The benefits of Active Roll Stabilization : Very high agility and equally precise steering characteristics. Very dynamic chassis responses. Minimal body roll for superior comfort in fast bends. (Available as an option for the BMW 5 Series, BMW 7 Series, BMW X5 and BMW X6 as well as for the respective M Performance models.) Adaptive Drive: the high-end chassis control system. The optional Adaptive Drive system is the high-end chassis control system from BMW. It combines the Active Roll Stabilization and Dynamic Damper Control systems with Servotronic power steering, which adjusts steering effort as a function of road speed. The Active Roll Stabilization and Adaptive Drive options provide maximum occupant comfort. They are available for the BMW high-end model series the BMW 5 Series, BMW 6 Series and BMW 7 Series (shown above). Sensors in the vehicle permanently monitor speed, steering angle as well as lateral and longitudinal vehicle acceleration. These data points are used to compute input for the adjustable stabilisers and dampers. The coordinated interaction between dampers and stabilizers counteracts centrifugal pull, thus ensuring less lateral tilt of the vehicle body and enhancing ride comfort. This results in improved directional stability, more precise steering responses and shorter braking distances. The benefits of Adaptive Drive: Maximum comfort. Optimal steering precision. Noticeably reduced body roll. Thus enabling higher cornering speeds and shorter braking distances. (Available as an option for the BMW 5 Series, BMW 6 Series and BMW 7 Series.)
Everything under control: optional BMW steering systems. In addition to the suspension, the steering is one of the key factors determining a vehicle s driving behavior. BMW has a unique reputation for its sensitive and precise steering systems. And BMW is equally known for innovative steering systems that adapt the steering to different driving situations to further enhance the typical BMW driving pleasure, much like the suspension and dampers can be adapted to suit different needs. Very precise steering with excellent road feedback is a hallmark of BMW automobiles. In addition, a number of adaptable and innovative steering systems are available as options. Variable Sport Steering: low steering effort, more agility. The Variable Sport Steering with Servotronic enables direct and agile handling combined with reduced steering effort. It works independently of road speed, varying the steering ratio in line with the steering angle. Unlike conventional systems with a constant steering ratio, the Variable Sport Steering uses a high ratio in the center and a low ratio on either side. This means that turning off into a side street or maneuvering into or out of a parking space requires fewer turns of the steering wheel. The additional Servotronic (speed-dependent, variable power steering support) enables the Variable Sport Steering to reduce the steering effort required to achieve a very large steering angle. This enhances sporting agility in tight corners and hairpin bends, as well as comfort when parking and maneuvering. For small steering angles and when travelling at higher speed, the system also provides excellent directional stability and a very high degree of steering precision. The benefits of Variable Sport Steering: Adapts the steering ratio to the driving situation. Enhanced comfort and reduced steering effort when maneuvering. Sporty driving experience thanks to high steering precision at higher speeds. (Available as an option for the BMW 2 Series, BMW 3 Series, BMW 4 Series and BMW X3.) Active Steering: easier maneuvering, more precise control. Unlike the mechanical Variable Sport Steering, the Active Steering system uses the support of an electric motor which employs a planetary gear set integrated into the steering mechanism to vary the steering ratio in line with requirements, to enhance steering comfort and agility. Vehicle with Active Steering: the rate at which steering wheel movements are translated into a movement of the front wheels varies depending on the car s speed. The result: precise and sensitive steering at any speed. < 12 mph > 37 mph This is how Active Steering feels to the driver: at speeds below 12 mph, when maneuvering into a parking space for example, only a small movement of the steering wheel is required. At higher speeds on the other hand, the steering wheel movement corresponding to a given steering angle becomes larger, and the steering gains precision. At lower speeds, for example in town, when parking and in hairpin bends, Active Steering reduces the steering wheel movement required to achieve a particular steering angle. This means that drivers can execute tight turns without having to adjust their grip on the steering wheel allowing for enhanced agility and easier parking. At higher speeds, in the range from about 75 to 85 mph (depending on model and set-up), Active Steering uses a more indirect steering ratio. The benefit: more steering precision. And Active Steering provides support even in critical situations such as oversteer or braking on surfaces offering varying levels of grip, by reducing yaw and other issues faster than even a seasoned driver could. Given that Active Steering is a complementary, hydraulics-based system, it does not interfere in the direct interaction between driver and wheels, meaning the BMW vehicle will remain fully maneuverable even in the event of a system failure. The benefits of Active Steering: Comfortable steering at low speed. Easy maneuvering. Precise steering at higher speeds. Enhanced ride comfort and directional stability. (Available as an option for the BMW X5 and BMW X6.)
Integral Active Steering: even the rear wheels are doing their part. Integral Active Steering combines rear-wheel steering with a variable steering ratio for the front axle to ensure even more stability, safety and comfort. A good view of rear-wheel steering, part of Integral Active Steering. At speeds of up to about 37 mph the rear wheels are turned in the opposite direction to the front wheels, significantly enhancing maneuverability. At speeds of up to around 37 mph, the rear-wheel steering system is operated in opposition to the front wheels up to a steering angle of three degrees. The driver perceives this as a shortening of the wheelbase, which considerably enhances the handling, agility and cornering ability of the car especially when maneuvering in tight spaces. At speeds above approximately 37 mph the rear wheels turn in the same direction as those at the front. This creates a sense of an extended wheelbase, enhancing directional stability and comfort especially during fast and sudden lane changes. The vehicle literally glides sideways in one continuous movement, which is especially pleasant for the rear passengers. Another safety benefit becomes apparent when braking on surfaces offering varying levels of grip, which can produce a loss of control: the countersteering required with conventional steering systems is no longer necessary. The Integral Active Steering system fulfils these tasks automatically, thus helping drivers stabilize their vehicles. The benefits of Integral Active Steering: Smaller turning circle and less steering effort at low speeds. Improved directional stability when avoiding obstacles at higher speeds. Enhanced comfort and safety at any speed. (Available as an option for the BMW 5 Series, BMW 6 Series and BMW 7 Series.) Key points: Chassis systems do not just determine the character of a vehicle, but also the character of a brand. BMW vehicles are renowned all over the world for their exceptional agility a reflection of their superbly fine-tuned chassis systems. Supremely versatile chassis, supporting anything from comfortable cruising to extremely sporty driving. Complemented by a diverse range of individual chassis and steering systems. Buyers can customize their BMW according to their personal chassis preferences. BMW chassis control systems: Dynamic Damper Control, Adaptive M suspension, Active Roll Stabilization and Adaptive Drive. BMW chassis control and steering systems increase comfort as well as safety in extreme situations as demonstrated for example here in BMW driver training. Steering systems: Variable Sport Steering, Active Steering and Integral Active Steering. Publisher Product News is produced by Bayerische Motoren Werke Aktiengesellschaft (Petuelring 130, 80788 München, Germany). Contact: Product.News@bmwgroup.com Edited for US Market by BMW of North America, LLC. BMW Group University 250 Chestnut Ridge Road Woodcliff Lake, NJ 07677 BMW AG is legally represented by its board of directors (Norbert Reithofer, chair, Milagros Caiña Carreiro-Andree, Klaus Draeger, Friedrich Eichiner, Klaus Fröhlich, Harald Krüger, Ian Robertson, Peter Schwarzenbauer). Chairman of the supervisory board: Joachim Milberg Registered office and court of registration: München HRB 42243 For further information please contact: Robert.Lallinger@bmw.de, BB-31 Keith.Edwards@bmwnaext.com, B2-US The German, English and French versions will be available in the Sales & Marketing Portal from 16/12/2014 (please click here). For internal use only. Copyright BMW AG, Munich (Germany). All rights reserved. Text, photographs, images, animations and videos are subject to copyright laws and other intellectual property regulations. Illustrations: BMW AG (BB-33).