Table of Contents M Chassis and Suspension Subject Page E60M5. Body. Suspension Components EDC-K. Selecting Program. Brakes . Rotors. Calipers. Dynamic Stability Control (DSC) .1 Operating Modes of the MK60E5 .11 MDynamic Mode (MDM).11 Hill Ascent Assistant.11 Condition Based Service (CBS) .11 System Components .13 Sensors .13 Control Unit.13 Hydraulic Unit.13 Pressure Generation .13 Engine Intervention .13 Interfaces.13 Initial Print Date: 05/09 Revision Date: IflimONNCOCOCDO Table of Contents Subject Page E90M3.14 Double-jointed Spring Strut Front Axle.15 Front Axle Carrier.15 Swivel Bearing .16 Spring Strut.16 Tension Strut.18 Wishbone.18 Wheel Bearing Unit.18 Front Anti-roll Bar.18 Steering System .19 Rear Axle .20 Wheel Carrier .21 Toe Struts .21 Camber Struts .21 Wishbone.21 Control Strut.21 Traction Strut .21 Rear Shock Absorbers .21 Electronic Damper Control - Continuous (EDC-K).22 EDC-K System Circuit Diagram .23 Wheels and Tires .24 Wheel/tire Specification .24 Brakes.24 Brake System Specification.24 Dynamic Stability Control (DSC) MK60E5 .25 Table of Contents Subject Page 4 M Chassis and Suspension M Chassis and Suspension Model: E60 M5, E63/64 M6 and E9x M models Production: From Start of Production After completion of this module you will be able to: • Identify the changes made to the suspensions of the M5, M6 and M3 when compared to the series production vehicles. • Explain the components used in the steering system of the M5, M6 and M3. • Identify the version of DSC used in the different M models. • Identify the braking system upgrades made to the M vehicles when compared to series production vehicles. E60 M5 Body The E60 M5 utilizes the same body construction as the produc¬ tion based 5 Series E60. The main body is made of steel and the front end utilizes the familiar GRAV technology. GRAV or "gewichtsreduzierter aluminiumvorderbau“ is a light¬ weight aluminum front end which enhances the lightweight design of the vehicle. Almost the entire front end is made of aluminum. The transition to steel in the composite construction starts in the vicinity of the engine bulkhead. The reduced weight of the front end in particular contributes much to the ideal axle-load distribu¬ tion of 50:50. M Chassis and Suspension 5 6 M Chassis and Suspension Suspension Components The control arms and transverse links are made of aluminum and ensure high-precision tracking of the wheels. The highly innovative design principle with the special layout of the leading links and control arms ensures high-precision steering. The low axle loads, especially in the area of the front axle, also provide for a high degree of agility and familiar BMW handling characteristics. Front Axle Index Explanation 1 Stabilizer Link 2 Hydro-Mount 3 Front Axle Carrier 4 Stabilizer Bar (No ARS) 5 Tension Strut 6 Swivel Bearing 7 Reinforcement Plate 8 Control Arm Index Explanation 1 Axle Carrier 2 Differential Bearing, rear 3 Stabilizer Bar 4 Control Arm 5 Traction Strut 6 Thrust Rod 7 Differential Bearing, front 8 Swinging Arm 9 Integral Link Rear Axle EDC-K Selecting Program The continuously variable electronic clamping control (EDC-K) system used in the E65/66 is used in the E60 M5. The continuous Electronic Damping Control (EDC-K) absorbs vertical forces while driving and dampens these forces to the chassis. The forces are measured by two vertical acceleration sensors on the front axle (left and right) and one at the rear axle (right). The front sensors are located in the wheel housings and the rear on the trunk tray underneath the trunk ventilation ports. The dampening characteristics are mapped in the control module to continuously regulate the EDC-K providing maximum comfort. The EDC-K works with infinitely variable valves in the dampers to regulate the hydraulic fluid flow using electromagnetic control valves. EDC-K provides the actual damping force required at any time. The steering angle sensor is used along with the front wheel speed sensors to determine the lateral acceleration. The controller provides the opportunity to select from three basic settings: “Comfort” - Comfort-oriented coordination of shock absorbers and steering “Normal" - Offers a balanced mixture of the comfort and the sports program “Sport” - Consistently sporty coordination of shock absorbers and steering. To select between the three programs available, press the EDC button repeatedly: "Comfort": No LED lights up in the button. "Normal": One LED lights up in the button. "Sport": Both LEDs light up in the button. The last selected program is active each time the engine is started. You can also activate your preferred program with the button on the steering wheel. Note: For further information regarding vehicle settings refer to the Performance Controls section of this training material or the Vehicle Owner’s Manual. M Chassis and Suspension 7 8 M Chassis and Suspension Brakes The M5 has braking distances equal to top sports car levels. The new BMW M5 owes its enormous braking power to double piston aluminum brake calipers and perforated, ventilated com¬ pound (floating) brake rotors. The braking distance for the M5 is approximately 118ft from 62 mph to a full stop. Front rotor of E60 M5 The front rotors measurements are 374 x 36 mm. The rear rotors measure 370 x 24 mm. Rear rotor of E60 M5 Rotors Both the front and rear rotors are cross drilled floating type. These ensure optimized heat dissipation, improved response, as well as reduction of unsprung masses. The rotor has an aluminum center section (hub) with pins embed¬ ded in a radial pattern that are “connected” to the rotor surface uti¬ lizing a free moving or floating configuration. This allows the rotor surface to contract and expand with the changes in temperature. Detail of Rotor Attachment Pins Detail of Rotor Alignment Pins on Hub The rotor is attached to the hub with two alien style screws and three alignment pins located on the hub. The rotor outer ring is cast and holes are drilled out to improve braking. The drilled surface allows gases that form between the brake pad and rotor to escape. Otherwise, there would be a thin film of “brake gases” between the surface of the rotor and the brake pads. Brake pads are made by gluing the friction material to a backing plate (metal). These are then baked in an oven to allow the glue to cure. While the brakes are heated, gasses are released and travel through the brake pads to the surface. This can be seen on any new brake pads as a lighter upper section of the brake pad (see picture below). Rear Brake Pads (“gasses”) Calipers The M5 utilizes dual piston brake calipers in the front and conven¬ tional single piston calipers in the rear. Dual Piston Front Brake Caliper Dual Piston Front Brake Caliper (close-up view) M Chassis and Suspension 9 10 M Chassis and Suspension Dynamic Stability Control (DSC) The E60 M5 is equipped with the Continental Teves Dynamic Stability Control System (DSC+) MK60E5. Although all E6x vehi¬ cles where updated to the Bosch traction control and stability sys¬ tem DSC8+ from 09/2005, the M5 still uses the Teves system. The MK60E5 system is also used in the E9x M3. The system is a further development of the MK60psi system. The abbreviation "psi" stands for "pressure sensor integrated" i.e. the two pressure sensors of the tandem master brake cylinder (THZ) have been combined to form one plausibility sensor and integrated in the hydraulic unit. The designation "E5" in MK60E5 signifies the 5 pressure sensors that are integrated in the hydraulic unit: One pressure sensor that measures the pressure from the tandem master brake cylinder THZ and four further sensors that measure the braking pressure of the respective wheel brake. This system offers functions that were not yet available with the previous system. MK60E5 added the following functions: • Brake Readiness • Dry Braking • Hill Ascent Assistant The features of this system distinctly enhance comfort during control intervention while facilitating even more precise individual wheel braking in connection with the analog control valves. This system made it possible to reduce the required braking dis¬ tance compared to previous systems. The E60 M5 has a braking distance of less than 118 feet from a speed of 62 mph (< 36 m from 100 km/h). Mounting Location of DSC Control Unit and Hydraulic Unit Compared to the standard DSC features, the MK60E5 in the E60 M5 has been upgraded by the following additional functions: • MDynamic Mode (MDM is activated via the M-Drive) • Brake readiness (Brake Standby) • Dry braking • Hill ascent assistant The following functions are not used on the M5: • Performance control (FLR) • Soft stop • Fading brake support (FBS) • Dynamic traction control (DTC) Operating Modes of the MK60E5 In principle, the MK60E5 has 3 different operating modes: • DSC ON • DSC OFF • MDynamic mode There is no DTC function in connection with the M5. However, similar to DTC mode, corresponding control thresholds are raised by activating the MDM. MDynamic Mode (MDM) MDM gives the performance-oriented driver the option of driving the car with controlled float angle and longitudinal slip without DSC intervening. The control system intervenes only when the physical limits are exceeded. MDM is activated via the M-Drive. The control thresholds are not static but rather, as the speed increases, they approach the thresholds of DSC ON mode. The stability control thresholds are identical as from a speed of approximately 125 mph (200 km/h) in order not to overtax the driver in the high speed range. Hill Ascent Assistant Assistance is provided when driving off on uphill gradients by briefly maintaining a specific brake pressure in the wheel brakes. This function is active only when the transmission is not in "N" position and the handbrake is released. DSC ON/OFF has no influence in this case. The tilt angle (uphill and downhill gradient) is calculated from the measured value of the longitudinal acceleration sensor. The DSC calculates the necessary holding pressure based on the uphill or downhill gradient. After releasing the brake pedal, the braking pressure is immediately decreased to the calculated holding pressure which is then reduced in stages after a maximum time delay of 0.7 seconds. The vehicle will start off after approximately 1 seconds if the driver does not press the accelerator pedal. The longitudinal acceleration sensor is assigned to the SMG system. The DSC control unit receives this signal over the bus net¬ work. Note: This function is also active on an incline with reverse gear engaged Condition Based Service (CBS) The MK60E5 calculates and evaluates the condition of the brake pads. In contrast to the E60 Series, the M5 is equipped with two brake pad sensors on the front axle. M Chassis and Suspension 11 12 M Chassis and Suspension DSC MK60E Hydraulics Diagram Index Explanation 1 Brake Fluid Reservoir 2 Rear Axle 3 Front Axle (hydraulic connection) 4 Pressure Sensor, push rod circuit 5 Pulsation Damper 6 Isolating Valve 7 Electric Changeover Valve 8 Self-Priming Return Pump 9 Damper Chamber 10 Accumulator Chamber 11 Front Left Inlet Valve with Orifice Plate, analog 12 Front Right Inlet Valve with Orifice Plate, analog 13 Rear Right Inlet Valve, analog 14 Rear Left Inlet Valve, analog 15 Rear Left Outlet Valve 16 Rear Right Outlet Valve 17 Front Left Outlet Valve 18 Front Right Outlet Valve 19 Front Right Wheel Brake 20 Front Left Wheel Brake 21 Rear Right Wheel Brake 22 Rear Left Wheel Brake System Components The predominant differences in the design of MK60E5 compared to MK60psi are: • Analog valves • 4 pressure sensors for individual braking pressure acquisition at each wheel. Sensors Hydraulic Unit The Teves MK60E5 hydraulic unit consists of: • Front axle - 2 analog inlet valves - 2 high-speed outlet valves -1 isolating valve -1 changeover valve Sensor system Principle Manufacturer Active wheel speed sensors Magnetoresistive principle Teves Steeiing angle sensor (LWS) in steering column switch cluster {SZL) Basic sensor, potentiometer technology Yaw rate sensor Double tuning tort; principle Lateral acceleration sensor Capacitive principle VTI 5 pressure sensors Piezoresistive [change in resistance in piezo) Brake light switch Hall principle Brake fluid level switch Peed contact switch Control Unit The control unit is mounted behind the left front wheel well cover and is attached to the hydraulic unit. It consists of: • Add-on control unit • Integrated semiconductor relay (motor and valve relay). • Rear axle - 2 analog inlet valves - 2 high-speed outlet valves -1 isolating valve -1 changeover valve Pressure Generation • Pump with two differential piston pump elements • Operated by means of common eccentric shaft • 250 W pump motor • ASC and DSC mode: Self-priming return pump Engine Intervention • Ignition timing adjustment • Charge control Interfaces • CAN-bus interface (F-CAN, PT-CAN) M Chassis and Suspension 13 14 M Chassis and Suspension E90 M3 The chassis of the E9X M3 is based on the chassis of the E9X series models respectively. All modifications are described in this section. E92 M3 Chassis Designation E92 M3 Series E92 335i Tire ty offset ae/Wheel rim type/Rim mm] 245-40 ZR 18/8.5 Jxl 8/ IS29 225-45 WR 17 RSC/8Jx1 71 IS34 Tire radius [mm] 305 295 Wheelbase [mm] 2761 2760 Track width [mm] 1538 1500 Total toe 16’ 14’ Toe differential angle 2° IT o 'nT o Camber -1° -18’ Kingpin inclination 15° 2’ 14° 7’ Kingpin offset [mm] 8.4 5.1 Trail [mm] 29.4 20.3 Trail angle 7° 8’ Double-jointed Spring Strut Front Axle Complete front axle Wheel suspension components Front Axle Carrier The front axle carrier is an aluminum alloy construction. In order to ensure optimum strength and torsional rigidity, a high-pressure forming technique has been used to manufacture certain sections. Aluminum has been chosen for its lightweight and strength proper¬ ties. The components of the front axle are joined together by an aluminum welding process. Front axle carrier Index Explanation Index Explanation 1 Rubber mount for tension strut 4 Wheel hub 2 Tension strut 5 Wishbone 3 Swivel bearing 6 Front axle carrier M Chassis and Suspension 15 16 M Chassis and Suspension Swivel Bearing The ’M’ swivel bearing is completely new. The bearing is made from an aluminum cast alloy, which reduces the weight by 500 grams. The following changes have been made to the front wheel carrier: • Adjusted dimensions for the larger M wheel. • As described below, the method by which the spring strut is clamped into the swivel bearing has been changed. • The geometric fixing points for the wishbone, tension strut and steering track rod have been selected to ensure opti¬ mum sports vehicle kine¬ matics. • Modified mounting posi¬ tion for the larger brake caliper. V Index Explanation 1 Clamp connection of the spring strut support 2 Attachment points for the tension strut, wishbone and steering track rod 3 Brake caliper mounting Spring Strut The front steel suspension spring has a 95 mm compression and 100 mm rebound travel. A new spring concept supports lateral chassis stability. Depending on the vehicle weight (eguipment), modified spring types are used. Index Explanation 1 Retaining nut, shock absorber to support bearing 2 Dowel pin, support bearing to body 3 Mounting fixture, support bearing to body 4 Joint seat 5 Support bearing 6 Upper spring seat 7 Support disc 8 Additional damper/spring 9 Gaiter 10 Lower spring seat 11 Spring strut Spring strut connection to the wheel carrier compared to the E9x series models Index Explanation A Spring strut support in the E9x series model 1 Vertical force (Z-axis) 2 Upper and lower limit for supporting lat¬ eral and longitudinal force (X and Y axis) 3 Clamp height 52 mm parallel fit 4 Parallel contact face Index Explanation B Spring strut support in the E9x M3 1 Vertical force (Z-axis) 2 Upper and lower limit for supporting lat¬ eral and longitudinal force (X and Y axis) 3 Clamp height 76 mm with parallel upper and conical lower fit 4 Upper cylindrical and lower conical contact face i*- M Chassis and Suspension 17 18 M Chassis and Suspension As shown in the diagram, the clamp height has been increased on the Z-axis from 52 mm on the E9x series model (left) to 76 mm on the E9x M3 (right). The front spring strut now has an additional support. The wheel carrier has also been modified to compensate for the increased drive and dynamic forces. The lower contact face of the spring strut in the E9x M3 has a cone, which is positioned firmly in the wheel carrier. In E9x vehi¬ cles, however, the front spring strut has a parallel construction and is only held in place by the clamping force. This design change and the increased clamp height accommodate the increased reaction forces of the spring strut and increase the overall stability of the wheel suspension. During assembly, the M3 spring strut is pulled into the lower cone using a new special tool. Note: Follow the installation and removal process accord¬ ing to the service repair instructions. Tension Strut The tension strut is similar to that used in the E9x series vehicles, but features an 'M'-specific harder rubber mount. Wheel Bearing Unit The M3 wheel bearing unit is identical to the E60 M5 wheel bear¬ ing unit. It has three dowel pins for the brake disc. Front Anti-roll Bar The weight-optimized front anti-roll bar was adapted for the M3 and has a special rubber bearing material for more direct response. The hinged brackets are made out of an aluminum alloy (steel in E9x series vehicles). Wishbone The M control arm is completely new and is connected to the axle carrier and wheel carrier by two ball joints. It is manufactured out of forged aluminum alloy. Steering System The design of the rack-and-pinion steering system is the same as in the E9x series vehicles. The average variable overall ratio is 12.5 (sports-oriented comared tol 6 in the E9x series). In the M3, the steering force support is controlled by the MSS60 via the Servotronic valve. A speed dependent characteristic curve is stored in the MSS60 for this purpose. With the MDrive menu option, a second and even more sports oriented characteristic curve can be activated (see the chapter on MDrive). The steering oil is guided through the steering oil cooler before it returns to the oil reservoir. The E9x M3 is not available with active steering. Index Explanation 1 Steering oil header tank 2 Steering oil hydraulic pump 3 Steering transmission housing 4 Steering oil cooler 5 Steering wheel spindle M Chassis and Suspension 19 20 M Chassis and Suspension Rear Axle The rear axle carrier is constructed from steel sections which are welded together. All mounting points for the rear axle and suspen¬ sion components are formed or attached to the axle carrier making it an integral component. Nearly all components of the rear chassis have been revised, the aim is to achieve optimum sports vehicle kinematics, chassis stabil¬ ity and a more precise and direct response, with a simultaneous reduction in weight. This has been achieved by the careful selection of materials for the axle components and bearings, and through a modification of the axle geometry. Construction of Rear Axle Designation E92 M3 Series E92 335i Tire typeAA/heel rim type/Rim offset [mm] 265-40 ZR 18/9.5Jxl 8 / IS23 225-45 WR 17 RSC/8Jx1 71 IS34 Tire radius [mm] 311 295 Wheelbase [mm] 2761 2760 Track width [mm] 1539 1513 Total toe 10’ 18’ Driving axis angle 0° 0° Camber -1° 45’ o 00 o Index Explanation Index Explanation 1 Wheel carrier 5 Wishbone 2 Toe struts 6 Shock absorber 3 Connections from control arm to rear axle carrier 7 Rear axle carrier 4 Camber struts 8 Traction strut with semi-trailing arm below it Wheel Carrier The attachment points for toe, camber, wishbone, longitudinal and traction struts have been positioned specifically for the 'M' model. Its overall dimensions allow for the larger M wheel to be fitted. The ’M’ wheel carrier is fitted with a modified rubber mount connecting to the semi-trailing arm and a ball joint for the camber strut. Toe Struts The new ’M’ toe strut is forged from Aluminum. It is one-piece and has two integrated ball joints. Camber Struts The 'M' camber strut is a new lightweight component forged from Aluminum. Its design reduces the unsprung mass of the vehicle. Wishbone The new 'M' wishbone is forged from aluminum and has a modi¬ fied integrated ball joint and a rubber mount. Control Strut The semi-trailing arm is the only rear suspension strut that is taken from the E9x vehicles. It is connected further inwards on the rear axle carrier, only the rubber mount is new. Traction Strut The geometry of the forged aluminum 'M' traction strut has been revised. It now has a new integrated rubber mount for the wheel carrier. The ball joint for the rear axle carrier has been taken from the E9x series vehicles . Rear Shock Absorbers New M specific rear aluminum dampers are fitted to the M3. Electronic damper control - continuous (EDC-K), is available as an option. The integrated lower damper rubber mount has a support sleeve that improves the rigidity and stability between the damper and the camber strut. Overview of rear axle struts Index Explanation 1 Wheel carrier 2 Toe strut 3 Camber strut 4 Control strut 5 Wishbone 6 Traction strut M Chassis and Suspension 21 22 M Chassis and Suspension Electronic Damper Control - Continuous (EDC-K) EDC-K is available for the first time in the E9x M3. EDC-K is an option and is based on the EDC-K in the E65 and E60 M5. Both dampers of one axis are always activated in parallel. The valve is installed internally in the damper in the damper oil system. console or preset via the MDrive menu and activated using the M button on the steering wheel (for more information, see the MDrive chapter). The input signals come from two vertical acceleration sensors in the front wheel arches and a third sensor in the rear right-hand wheel arch. The compression phase, and in particular the rebound phase, of the shock absorbers can be adjusted by the EDC-K depending on the input signals in a smooth transition from relatively comfortable to a harder sports setting. The driver can choose between three settings, the controlled pro¬ grams "Comfort" and "Normal", or the uncontrolled fixed setting "Sport". The program is selected using the EDC-K button on the center The steering column switch cluster sends the steering angle to the F-CAN. This is transmitted together with the wheel speeds from the DSC to the PT-CAN and evaluated in the EDC-K control unit. The longitudinal, lateral and vertical accelerations calculated as a result are used as a basis for regulation. The EDC-K button signal enters the junction box and is transmitted to the EDC-K on the PT-CAN. EDC-K System Circuit Diagram Index Explanation 1 EDC valve, front right 2 Vertical acceleration sensor, front right 3 Junction box/distribution box 4 EDC-K control unit 5 Vertical acceleration sensor, rear left 6 EDC valve, rear right 7 EDC valve, rear left 8 EDC button on center console 9 Steering column switch cluster 10 DSC control unit 11 Vertical acceleration sensor, front left 12 EDC valve, front left M Chassis and Suspension 23 24 M Chassis and Suspension Wheels and Tires In the standard version, the cast 18" 'M' double spoke wheel (style 260) is available for the E9x M3, with the forged and polished 19" 'M' double-spoke wheel (style 220) available as an option. These are weight-optimized M3 light alloy wheels. The tires are also specifically selected for the M3. The Michelin Pilot Sport (PS2*) is currently fitted. Wheel/tire Specification Standard wheel: Front - Wheel: 8.5 J x 18; IS 29; EH2+ Tires: 245-40 ZR 18 Rear - Wheel: 9.5 J x 18; IS 23; EH2+ Tires: 265-40 ZR 18 Optional: Front - Wheel: 8.5 J x 19; IS 29; EH2 Tires: 245-35 ZR 19 XL Brakes The M Compound brake system with perforated brake discs and three 'M'-typical brake pad wear sensors is used, with a specifically adapted operating principle and dimensions.. The diameter of the brake discs has increased compared to the E46 M3 by 35 mm at the front, and by 22 mm at the rear. Brake System Specification Front brake: Diameter 360 mm, thickness 30 mm, direction-spe¬ cific ventilation, single-piston floating caliper (light¬ weight metal alloy), brake pad wear sensor right and left. Rear brake: Diameter 350 mm, thickness 24 mm, direction-specif¬ ic ventilation, internal handbrake with 185 mm diame¬ ter (similar to E60 M5), single-piston floating caliper (cast metal alloy), brake pad wear sensor on right. Rear - Wheel: 9.5 J x 19; IS 23; EH2 Tires: 265-35 ZR 19 XL Dynamic Stability Control (DSC) MK60E5 The E9x M3 is equipped with the MK60E5 DSC system made by Continental Teves, which has been specifically adapted to its driv¬ ing dynamics. The "civilian" version is installed in several non-M models. The fundamental difference in both versions is the replacement of Dynamic Traction Control (DTC) with M Dynamic Mode (MDM). MDM has been adapted to suit sports car dynamism for experi¬ enced sports drivers. The permitted float angle and longitudinal slip in good environmental conditions (road, weather, etc.) are also equally high. Furthermore, the driving-performance control (FLR), soft stop and Fading Brake Support (FBS) functions are not required in the 'M' version. The braking readiness (applies the foot brake and the handbrake until the discs and drums are dry) and the gradient assistant func¬ tions have been adapted appropriately. Note: An M-specific version of the MK60E5 is installed in the E6x M5 and M6. For further information regard¬ ing DSC systems refer to the Chassis Dynamics training material available in TIS and ICR M Chassis and Suspension 25 26 M Chassis and Suspension