Corrosion damage on wheel suspension parts has been noticed in recent years by the Swedish Motor Vehicle Inspection Company in their annual control inspection of motor cars. This type of damage, which affects relatively new cars, has not occurred on earlier models to any great extent. Since the breakdown of a wheel suspension can lead to a traffic accident, it has been considered necessary to investigate the problem. By evaluating results from the yearly inspections of motor cars, different car models could be judged with respect to extent and age of corroded vehicles. Damaged wheel suspension parts, especially spring mountings of the McPhearson type, were analysed to explain the causes of the corrosion.
To promote traffic safety in Sweden the Swedish Motor Vehicle Inspection Company is responsible for the annual control inspection of motor cars. The age of the car fleet in Sweden has increased according to Fig. 1 if the situation in 1979 is compared with that in 1989. Despite the fact that the average inspected car is older, the corrosion on the car body has decreased if the observation frequencies in different years of inspection is compared, Fig. 2. The most common reason for observations on defects in the structure is perforation corrosion on body parts such as side members, cross members, floor, wheel arches, door pillars and mounting points for chassis components.
During recent years, an increased amount of corrosion damages on wheel suspension parts has however been noticed. This initiated a cooperative investigation between the Swedish Corrosion Institute and the Swedish Motor Vehicle Inspection Company to map out the extent and to analyse the causes of the corrosion problems on the wheel suspension parts on motor cars.
