BMW 8 Series Convertible Now Official, Starts at $121,400
BMW xDrive Electronically-controlled Differential Lock
The BMW xDrive intelligent all-wheel-drive system has been improved for more efficient operation. With its rapid, precise and fully variable distribution of drive torque between the front and rear wheels, it maximizes traction and handling stability not just when driving in adverse road conditions, but in performance driving situations as well. Power is split in accordance with demands at all times using an electronically controlled multi-plate clutch that is networked with the powertrain and chassis systems. This results in extremely quick and exact response to any change in the driving situation.
To increase the system’s efficiency, all of the drive torque is directed to the rear wheels in situations when all-wheel drive is not needed. The xDrive system’s rear-biased set-up guarantees a driving experience for which BMW sports cars are renowned. The fact that the all-wheel-drive system has been specifically designed for performance handling is especially noticeable in the SPORT and SPORT+ modes selected via the Driving Experience Control switch.
Governed by the Driving Stability Control (DSC) system, the locking function for the standard electronically controlled rear differential improves traction and power transmission when driving on road surfaces offering differing levels of grip for the left and right rear wheels by preventing a wheel from spinning when traction is limited. The locking effect produced by the electric motor allows the drive torque to be redirected from the faster turning to the slower turning tire. This combines with the intelligent all-wheel drive and the standard Integral Active Steering to give the car all the right tools for excellent handling and remarkably agility in all driving situations.
Sharpened Racing Suspension
The suspension technology developed for the first-ever BMW 8 Series Convertible consists of a double-wishbone front axle and a five-link rear axle as well as electromechanical steering and an exceptionally powerful braking system developed exclusively for this new model. The racing know-how of BMW M GmbH was used for detailed modifications and enhancements to the overall suspension set-up. Torsion struts on the front axle and a load-bearing strut incorporated on the rear axle optimize stiffness and the connection of suspension components to the chassis. Independent rubber bearings – which increase camber stiffness – and additional damping plates at the rear axle further enhance the suspension’s baseline set-up. Special wheel hubs and wishbones allow camber values on both axles to be raised as far as possible. This significantly increases the car’s ability to put down power through high-speed corners.
The design principle of the double-wishbone front suspension makes it possible to separate steering and damper functions. As a result, high lateral acceleration forces are possible without compromising ride comfort. The car’s steering remains largely unaffected by disruptive forces caused by irregularities in the road surface. Thanks to bi-elastic bushings, the five-link rear axle guarantees precise wheel guidance and the highest degree of directional stability. In addition, effective isolation of the powertrain and suspension improves interior acoustic comfort.
Adaptive M Suspension & Integral Active Steering
Standard on the BMW 8 Series Convertible is Adaptive M suspension with electronically controlled dampers. Both compression and rebound are adjusted continuously and independently. This facilitates finely tuned spring and damping responses, providing the driver with only relevant information about the road surface. The extremely stiff suspension springs reduce roll tendency and allow the dampers to stabilize the wheels as much as possible, avoiding traction losses caused by bumps and ruts in the road surface. The electronically controlled dampers respond adaptively to road surface conditions and driving style in order to eliminate undesired vehicle movement. Minor road damage is comfortably filtered out and narrow bumps do not induce unwanted pitching movements.
Damping characteristics can be adjusted via the Driving Experience Control switch. SPORT and SPORT+ modes activate optimal responses for maximum handling. This is noticeably different from the comfort-oriented damper setting in ECO Pro and COMFORT modes.
The standard Integral Active Steering also reduces the car’s turning circle when maneuvering, increases agility at moderate speeds and optimizes stability when changing lanes and cornering at high speeds. The system combines the electromechanical steering of the front wheels (including Servotronic function for speed-sensitive power assistance) and the variable steering ratio in the rear axle steering.
In order to achieve maximum precision during performance cornering, the steering of the first-ever BMW 8 Series Convertible becomes more direct with speed. As a result, on winding roads the car feels particularly agile and easy to control. The variable steering ratio also provides additional comfort; allowing the driver to maneuver at low speeds with minimal steering wheel movement and without having to change their grip on the wheel. By contrast, at high speeds, the same steering wheel movement results in decreased steering response, optimizing turn-in precision.
Active steering of the rear wheels by up to 2.5 degrees – thanks to Integral Active Steering – considerably enhances the cornering ability of the first-ever BMW 8 Series Convertible. The rear wheels are steered in the opposite direction to the front wheels at speeds up to 45 mph. At higher speeds, the steering angle of the rear wheels matches that of the front wheels, ensuring the car adopts the course determined by the driver quicker and more accurately. At the car’s traction limit, it feeds in a stabilizing steering input to complement the triggered braking intervention.
Activating SPORT or SPORT+ model via the Driving Experience Control switch gives a more direct steering response. At the same time, the maximum speed at which the rear wheels are steered in the opposite direction to the front wheels is increased to 55 mph.
Active Roll Stabilization
Active roll stabilization is optionally available for the BMW M850i xDrive Convertible and further enhances the car’s sporty handling characteristics. Electric swivel motors on the front and rear anti-roll bars ensure fast and precise compensation for lateral forces during dynamic driving maneuvers. The system is controlled through a constant analysis of vehicle speed, lateral and longitudinal acceleration, steering wheel position, wheel and body acceleration and variation in height levels. In BMW M Performance models, active roll stabilization has an exceptionally sporty set-up and responds adaptively to changing requirements. It optimizes agility and directional stability on turn-in and helps line the car up as neatly as possible for improved acceleration out of corners. The reduced body movement also means that fast evasive maneuvers can be executed with great assurance.
At the opposite end of the spectrum, the system increases comfort when driving straight ahead by decoupling the permanent anti-roll bar connection between the wheels of an axle. By stabilizing the wheel that requires it, the system is extremely effective in counteracting disruptive forces resulting from road surface imperfections on one side of the car.
M Sport Brakes, Light-alloy Wheels, High-performance Tires
Powerful braking characteristics, high thermal stability, fast response and excellent feel characterize the braking system developed for the first-ever BMW 8 Series Convertible. Four-piston, fixed-calliper brakes at the front are complemented by single-piston, floating-calliper brakes at the rear. The electronic parking brake – operated by means of a button located on the center console – is integrated into the rear brake callipers. The integration of the braking system and DSC stability control guarantees precise braking response, braking control and brake boosting.
Inner-vented brake discs and model-specific brake pads are featured both at the front and rear. Directional cooling air ducts help to reduce temperatures. The friction rings of each brake disc are riveted to an aluminum drum. Together with the use of aluminum brake callipers, this BMW-patented construction concept significantly reduces unsprung weight.
The suspension technology featured in the new BMW M850i xDrive Convertible is oriented towards maximum performance and rounded off by 20-inch M light-alloy wheels. The cast aluminum wheels are standard and come in the exclusive color Frozen Cerium Grey metallic with a high-gloss polished finish on the face. They are fitted with 245/35R20 tires at the front and 275/30R20 tires at the rear. The high-performance tires were developed by the manufacturer specifically for the BMW 8 Series Convertible.
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