System Components
Front Axle: The traditional double pivot spring strut axle with tension rods is used. The double pivot refers to the lower mounting of the strut and hub carrier around which the wheel turns. The lower control arm and the tension rod form the two lower physical pivot points. The lower pivot point is actually an imaginary point formed by the extension of the control arm and tension rod.
This suspension system is preferred because of these excellent features:
- Constant tracking over the entire compression and extension travel of the suspension.
- Camber change (reaction) during compression.
- Straight-ahead driving with 0 mm kingpin offset (also reduces steering effort) even though wide tires are used.
- Anti-dive control (during braking).
- Fewer components (weight savings).
The double pivot front axle of the is bolted to the body sub-frame.
Front Axle Carrier: The materials used in the front axle carrier offer high tensile strength to support extreme loads. The front axle carrier is also manufactured from aluminum. It consists of cast alloy preformed sections which are welded into the extruded sections.
The front axle carrier accommodates the steering gear, control arms and tension struts, engine mounts, stabilizer bar, heat shield and the underbody panels.
An "thrust zone" panel is bolted on to increase the transverse rigidity of the front of the vehicle. This reinforcement has a positive effect on the handling, sound level and crash performance.
The benefits as a result of the improved front axle include increased agility, improved comfort by the reduction of unsprung weight, a reduction in fuel consumption by lowering the gross vehicle weight and better axle load distribution.
Control Arms: The control arm locations are similar to the E39 528i with a single control arm and tension rod per side. The layout of the arms combined with the tensioning rods located in front of the wheel center provides balanced steering during cornering.
The hydro mounts in the front of the tension rods contain hydraulic fluid in internal channeling to dampen wheel vibrations.
Small vibrations are cushioned by these mounts and isolated from the steering wheel.
Stabilizer Bar: The standard stabilizer bar (1) is designed as a tubular stabilizer bar, which minimizes body "roll" during cornering. It is connected to the spring struts by links (rods) to provide the best performance leverage.
The connection on the spring strut is high mounted so that when driving straight ahead and hitting a bump on one side, the spring strut will not be turned (bump steer).
The active roll stabilizer bar (ARS) will be covered in Dynamic Drive.
Spring Strut, Hub Carrier and Wheel Bearing: The twin tube gas pressurized shock absorbers and the hub carrier are bolted together. The tube is made of aluminum and has a locating tab on the side which is used to align it into the hub carrier in the correct position.
The tube and hub carrier are produced in left and right versions and are identified by a label. The wheel bearing assembly is bolted onto the hub carrier.
Upper Mount: The upper mount contains the spring strut support bearing and a centering pin (1) inserted to retain the factory preset camber.
The centering pin can be removed for minor camber adjustments (+/-18') provided by slots in the strut tower under the upper mount securing nuts.
The cable shown in the diagram is the connection for the EDC-K which will be covered in Dynamic Drive.