BMW 5-Series

The BMW E39 is the BMW 5 Series made between 1995 and 2003. A mid-generational refresh appeared in 2000, featuring minute detail changes.

For the 2001 model year, BMW updated the E39 with newer, clear-lens tail, side marker, and headlights which first displayed the now-popular "angel eyes." Rear tail lights were changed to "wave-guide" LEDs, while the side and rear turn signals were changed from amber lenses to clear. The black trim was now painted to match the body color, and the front bumper now featured rounded fog lights. Internally many changes were made to electronics; items such as window regulators and the air conditioning were updated. The 528i was replaced by the 530i which had a new 228 hp M54B30 3.0 L inline-6. A new entry-level 525i was introduced featuring a 192 hp M54B25 2.5 L I6 and a slightly lower price.

The E39 all-steel body acts as a safety cage for occupant protection. The structural rigidity of the monocoque was increased using computer-aided engineering. This allows key points to be reinforced, to increase rigidity, without significantly adding to the weight. The overall increase is 20 pounds, which is offset by the aluminium suspension. Laser welding techniques ensure rigid bonding throughout. Another area of focus in the design of the body was in structural dynamics. The body was designed so that the frequencies for torsional twisting and bending are in separate ranges and above natural frequency. These frequencies are out of the range of engine and driveline vibrations; thus they will not amplify them.

With the E39, two steering types and double pivot, MacPherson strut suspensions systems are used. For the 520i–530i models, BMW, for the first time in a 5 series, utilized rack and pinion steering. This not only offers weight reductions over the recirculating ball type used on the V8s, but also provides quicker steering response through its variable ratio, as well as a more precise feel. This system steers from the front of the axle.

Six-cylinder models also receive an aluminium front subframe. The struts use aluminium "Tension Link" that comes from a forward position back to the front of the wheel and an aluminium horizontal link to locate them. Aluminium is used for the steering knuckles, outer strut tube, and the spring pads; saving 21 kilograms 46 pounds.

With the 540i, BMW retained the front steering and suspension from the previous E34 540i with the design based on the E38 7 Series. The physical size, dimensions, and weight of the V8 engine required the use of the older recirculating ball steering. This system steers from the back side of the axle. The front subframe is steel. To compensate for the heavier front end, BMW used extra aluminium in components including the steering box, steering knuckles, outer strut tube, and the spring pads. The struts are located by an aluminium "Thrust Link" that comes from the rear to meet the back of the wheel and an aluminium horizontal link.

Source: Wikipedia, 2012

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