New BMW M3 Coupe (E92) - In Depth

Page 1: Short story
Page 2: Concept
Page 3: Power unit
Page 4: Chassis & suspension
Page 5: Design
Page 6: Body
Page 7: Safety
Page 8: Features
Page 9: Production

Chassis and Suspension

Turning Superior Performance into Supreme Dynamics

Front and rear axles reinforced but nevertheless lighter than before.
Newly developed Variable M Differential for optimum traction.
Electronic dynamic driving systems with optional customisation to the driver’s requirements.

Spreading out steering and drive forces on the front and rear axle, the new BMW M3 offers ideal conditions for supreme dynamic performance, very good directional stability and safe handling.

Indeed, the “regular” BMW 3 Series Coupé serving as the basis for the new BMW M3 provides the ideal configuration for a particularly agile high-performance sports car right from the start through its rear-wheel-drive concept. The fact remains, however, that the significant increase in engine power to 309 kW/420 hp on the new BMW M3 presented the chassis and development specialists with a number of new challenges. Once again, therefore, the task was to live up in full to the supreme standards of BMW M GmbH, with the chassis and suspension offering an ever greater dynamic potential than the engine.

Like their colleagues developing the power unit, the chassis and suspension specialists at BMW M GmbH therefore used their many years of experience in the construction of high-performance cars for this purpose, giving the new BMW M3 a chassis and suspension brand-new in nearly every respect and naturally taking the particular requirements of this high-performance model into account.

The objective in the development process was not only to match the qualities of the chassis and suspension to the outstanding power and performance of the eight-cylinder power unit, but also to save weight wherever possible. Precisely this is why nearly all components on the double-joint front axle are made of aluminium – among them the even stiffer spring struts, the pivot bearings, the central subframe and an additional thrust panel beneath the engine serving to maximise the lateral stiffness of the entire front section.
And the anti-roll bar constructed as a hollow tube likewise serves to optimise both the appropriate function and the weight of the suspension.

With the exception of one single track control unit, the components on the five-arm rear axle of the BMW M3 also built in lightweight technology are likewise brand-new from the ground up. The anti-roll bar at the rear, in turn, is also a hollow tube for reasons of optimum function and minimum weight. Together with the axle control arms in forged aluminium and the aluminium dampers, these technologies and light materials serve to reduce weight by approximately 2.5 kg versus the former suspension.

Enhanced directional stability on the rear axle – using, inter alia, two additional longitudinal arms – and appropriate axle kinematics ensure a high standard of driving dynamics suitably matched to the power of the engine. Indeed, the very dynamic performance of the new BMW M3 was even taken into consideration in the design and construction of the cover on the final drive, which comes complete with cooling fins in order to optimise the dissipation of heat.

Variable M Differential Lock for enhanced traction and driving dynamics.

The new final drive on the BMW M3 features a Variable M Differential Lock ensuring a perfect response to any difference in speed between the right- and left-hand rear wheel and providing up to 100 per cent locking action in a fully variable process. Whenever necessary, therefore, the Variable M Differential Lock feeds more engine power to the wheel with better grip, thus ensuring optimum traction on all surfaces.

These benefits come to bear particularly on a fast mountain pass, where with a conventional system the inner wheel in a bend may easily start to spin due to the reduction of load forces. Accordingly, a conventional differential lock taking only torque into account might reduce drive forces more than required in an attempt to prevent the inner wheel from spinning.

By contrast, the Variable M Differential Lock, with its ability to detect the speed of rotation, controls locking action appropriately and individually as required under all conditions. Indeed, this solution provides ideal support, enhancing the positive qualities of rear-wheel drive to a new, unprecedented standard.

The new BMW M3 benefits from the Variable M Differential Lock also in its driving qualities in winter. With a conventional differential lock, the total amount of drive forces the wheels are able to convey to the road depends on the force conveyed by the individual wheel with the lowest frictional coefficient – which often means a significant limitation of traction on snow, gravel or ice. The speed-sensing Variable M Differential Lock, on the other hand, gives the car a decisive advantage in terms of traction even under very different frictional conditions, even ensuring in an extreme case that all the drive power is conveyed to the wheel with better traction and grip.

The compound brake system: light, powerful, reliable.

The new BMW M3 features an appropriately large and powerful brake system with compound brake discs. The inner-vented, cross-drilled grey cast iron discs measuring 360 mm (14.2´´ ) in diameter at the front and 350 mm (13.8´´ ) in diameter at the rear are connected by cast-in stainless-steel pins to the aluminium disc carrier in floating arrangement. With this configuration significantly reducing the thermal loads acting on the brake discs, the service life and, in particular, performance of the discs is increased accordingly.
A further advantage is that the configuration of this high-performance brake system allows a further reduction of weight.

The vacuum required for the brake power servo is generated by an electrically driven pump, an ongoing wear indicator enabling the driver to permanently monitor the condition of the brake linings, with a display in the cockpit informing the driver of their remaining service life. Clearly, this not only enhances the standard of driving safety on the road, but also avoids unnecessary service and maintenance.

The new BMW M3 comes as standard on light-alloy wheels in specific M design. The front wheels measure 8.5 x 18 inches and run on 245/40 low-profile tyres, the rear wheels are 9.5 x 18 inches In size and run on 265/40 tyres.

Servotronic with two manually preselected control maps.

Benefiting from rear-wheel drive, the rack-and-pinion steering on the new BMW M3 remains free of drive forces. Steering qualities are enhanced by hydraulic Servotronic power assistance controlling steering forces as a function of road speed. The driver, in turn, is able to vary the degree of power assistance by means of iDrive control, choosing from two different control maps by activating either the Normal or the Sports mode.

The Sports mode retains the very direct feeling of feedback from the road, enabling the driver to steer the car with utmost precision also at high speeds on winding country roads. The Normal mode, in turn, ensures more comfortable steering assistance, enabling the driver to park the car, for example, much more easily and with minimum effort.

Latest generation of Dynamic Stability Control.

It almost goes without saying that the driver of the new BMW M3 benefits from electronic dynamic driving programs whenever encountering the limits to driving physics: Dynamic Stability Control (DSC) permanently monitors driving conditions and, whenever necessary, intervenes individually in the wheel brakes and reduces drive power in order to stabilise the car. Inter alia, this serves to counteract any over- or understeer in bends.

Dynamic Stability Control comprises a number of additional functions such as the anti-lock brake system (ABS), anti-spin control (ASC) preventing the wheels from spinning on surfaces with reduced traction, a Start-Off Assistant preventing the car from rolling back when setting off on an uphill gradient, as well as Cornering Brake Control (CBC) preventing the car from spinning when applying the brakes in a bend.

A further advantage of DSC is that it compensates any fading of the brakes at extremely high temperatures by increasing brake pressure accordingly.

Enhanced to an even higher standard than before, DSC Dynamic Stability Control on the new BMW M3 now also comprises additional functions in the interest of driving safety. Whenever the system recognises that the driver is about to apply the brakes all-out, for example, it builds up pressure in advance in the hydraulic brake system and pre-loads the brake pads, gaining valuable time in the process and significantly shortening stopping distances.

Yet a further function of DSC is regular dry braking in the wet, ensuring that the brakes are applied even under such conditions without the negative effect of a layer of water on the brake discs.

Electronic Damper Control recognising the driver’s particular style of motoring.

As an option the dampers on the new BMW M3 may be equipped with EDC Electronic Damper Control adjusting damper forces in an electrohydraulic process and thus not only optimising vertical oscillation of the car under dynamic driving conditions, but also significantly reducing the car’s dive and roll behaviour when applying the brakes and when accelerating. Equipped with EDC, therefore, the new BMW M3 is capable of far higher speeds in bends.

The response and behaviour of all dynamic driving programs is naturally geared to the supreme performance of the new BMW M3, with the various electronically controlled systems intervening appropriately as a function of the car’s outstanding dynamic driving characteristics. A further point is that the driver is able to individually configure certain parameters as required, thus matching the reactions of the car to his personal wishes and preferences.

One example is that the driver is able to completely deactivate Dynamic Stability Control by means of a push button in the centre console, a function which enables the particularly ambitious sports driver to enjoy the full dynamic potential of the new BMW M3 under appropriate conditions. When driving this sports car on the race track, the dedicated driver thus has the option to go all the way to the most extreme dynamic limits, enjoying the thrill of an optimum power slide in bends.

The effect of Electronic Damper Control can also be varied according to the driver’s individual wishes and preferences, offering the choice of three settings: Normal, Comfort, and Sports again selected simply by pressing a button on the centre console.

Clearly, EDC Electronic Damper Control on the new BMW M3 comes from the start with a particularly sporting and dynamic configuration permanently retained as long as EDC is in the Sports mode. Whenever a particularly dynamic set-up of the dampers is not required, on the other hand, the driver is able to switch to the Normal or Comfort mode.

In this latter case the dampers respond adaptively – and just as quickly and sensitively as usual – to any change in the driver’s style of motoring. Then, as soon as higher steering angle speeds indicate that the driver is about to adopt a more dynamic style of motoring, damper forces are increased automatically, EDC switching to a damper control map comparable to the Sports mode regardless of the control map currently activated.

As a result, EDC offers perfect support in switching spontaneously from a more comfort-oriented style of cruising to a sporting and active style of motoring. Indeed, this intelligent management of damper systems ideally reflects the all-round character of the BMW M3 ensuring outstanding sports performance at all times.

Engine management likewise comes with three control maps again retrieved via iDrive. Apart from varying the position of the throttle butterflies in the intake manifold, these control maps also act on other parameters with a significant effect on the response and behaviour of the engine. And last but not least, iDrive also serves to program the Servotronic power assistance with the two Normal and Sports set-ups.

MDrive button for the ambitious driver.

The iDrive control system may be further enhanced on the new BMW M3 by the addition of MDrive as an option. This gives the driver the opportunity to pre-select his personal setting on all dynamic driving systems which may be individually configured, thus choosing the perfect set-up of the car geared precisely to his personal preferences.

This individually defined configuration is saved in the system and may be retrieved immediately whenever required simply by pressing the MDrive button on the multi-function steering wheel, regardless of the system configurations previously selected by way of other function buttons.

This gives the driver of the BMW M3 the wonderful opportunity to enjoy the versatile character of his car in every respect and with all its facets – simply pressing one single button to change over to his personal set-up of the new BMW M3.