Aluminum/Steel Construction Of The BMW 5 Series
Short summary:
Aluminum/Steel Construction Of The BMW 5 Series The most interesting characteristic about the 2004 BMW 5 Series, from a collision repair perspective, is its construction ...
Long summary:
Aluminum/Steel Construction Of The BMW 5 Series The most interesting characteristic about the 2004 BMW 5 Series, from a collision repair perspective, is its construction. The front-end structure from the cowl forward is all-aluminum, while the rest of the vehicles structure is steel. The front portion of the lower rails is aluminum; the portion of the lower rails under the floor pan is steel. A rear portion of the upper rails is steel, however the rest of the upper rails are made of aluminum. The floor pan and the lower portion of the A-pillars are steel, both joined to an aluminum cowl panel. The first questions that come to mind are why and how. Why make only the front-end structure out of aluminum? How is aluminum and steel joined while avoiding galvanic corrosion? The why can be answered by considering that an aluminum structure can be just as strong as a comparable steel structure with about one-third less weight. The aluminum front assembly allows the new 5 Series to be slightly longer, wider, and taller than previous model years but still weighs about 20 kg (44 lb) less (see Figure 1). With the front structure made of aluminum, there is almost a near equal weight distribution between the front and rear of the vehicle. Also, with the rear half made out of conventional steel, theres better repairability, necessary for a high volume production vehicle. Aluminum/Steel Construction Of The BMW 5 Series When bare aluminum joins with bare steel, contact or galvanic corrosion can result. Where aluminum meets steel in the 5 Series main structure, the joints are made using adhesives and rivets, a process known as rivet-bonding. Everywhere aluminum and steel come together, the adhesive protrudes at least one millimeter outside the joints. This helps ensure that direct contact between bare steel and aluminum is completely avoided. The steel panels are also galvanized and the aluminum panels are treated with a titanium/zircon coating designed to both hinder oxidation and enhance the adhesive bonding surface. After construction, the entire vehicle is also subjected to a phosphate bath and E-coat. Aluminum part construction used for vehicles is either stamped, extruded, or cast, and the 5 Series uses each of these in the front-end structure. The strut tower/apron assemblies are cast construction. The inner part of the lower rails (engine carriers) are extruded construction, while the outer portion is stamped. The upper cowl panel is extruded and hydroformed. The upper rails and cowl panels are stamped. The alloys are 5000 and 6000 series. Besides the front structure, the driveshaft, suspension system, engine mounting brackets, transmission crossmember, rear subframe, and several exterior panels are also aluminum. November 10, 2003 Technical Information For The Collision Industry Figure 1 The structure on the 2004 BMW 5 Series is aluminum from the cowl forward and the rest conventional steel. ...
Source: www.i-car.com
Related
SUBJECT E39 BMW Accessory Navigation System Speed Input Signal, SI E39 BMW Accessory Navigation System
Speed Input Signal. BMW AG TIS.
20.07.2001 17:48. Issue status (05/2001)
Valid only until next CD is issued ...,
more
SI Ordering the OnBoard Navigation Map Software, Map software for the BMW OnBoard
Navigation System is only current for a
sixmonth period. SI Ordering the OnBoard
Navigation Map Software. BMW AG TIS ...,
more
Original BMW Accessories. Installation instructions., BMW AG Mnchen. 01 29 0 412 215. 12.2005
(Z/S). 2. Preparatory work. TIS No.
Perform quick test. . Disconnect negative
terminal of battery ...,
more
