Body flex
Encyclopedia
Body flex is a lack of rigidity
in a motor vehicle
's chassis
. It is often something to be avoided by car manufacturers as higher levels of body flex is a sign of structural weakness, and means that the vehicle's suspension
cannot work as efficiently - the body takes up some of the 'slack', rather than the parts of the car which were specifically designed for this purpose. A chassis that flexes may be prone to fatigue and further "softening" with use will eventually result in failure. Cars of a sporting nature are, therefore, often very 'stiff', while convertibles or cabriolets are not often considered to be good candidates for high-performance sports cars because of their lack of a rigid roof.
Although, for some time, body flex was a result of attempts to keep a car's weight down, makers such as Audi
(the A8
), and Jaguar
(with the 2003 XJ8
) have employed the use of aluminium
in chassis production to get around this obstacle, ensuring the weight of these cars and their level of body flex can both be kept to a minimum.
Typically, the stiffness of the body is measured in torsion. The body is supported at the spring caps at the rear, and then a torque is applied to the front spring caps via a long beam and a fulcrum. Values achieved range from 1000 lbft per degree for pre-War racing cars, up to 25000 lbft per degree for some modern production vehicles.
Rigidity
Rigid or rigidity may refer to:*Stiffness, the property of a solid body to resist deformation, which is sometimes referred to as rigidity*Structural rigidity, a mathematical theory of the stiffness of ensembles of rigid objects connected by hinges...
in a motor vehicle
Motor vehicle
A motor vehicle or road vehicle is a self-propelled wheeled vehicle that does not operate on rails, such as trains or trolleys. The vehicle propulsion is provided by an engine or motor, usually by an internal combustion engine, or an electric motor, or some combination of the two, such as hybrid...
's chassis
Chassis
A chassis consists of an internal framework that supports a man-made object. It is analogous to an animal's skeleton. An example of a chassis is the underpart of a motor vehicle, consisting of the frame with the wheels and machinery.- Vehicles :In the case of vehicles, the term chassis means the...
. It is often something to be avoided by car manufacturers as higher levels of body flex is a sign of structural weakness, and means that the vehicle's suspension
Suspension (vehicle)
Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. Suspension systems serve a dual purpose — contributing to the car's roadholding/handling and braking for good active safety and driving pleasure, and keeping vehicle occupants...
cannot work as efficiently - the body takes up some of the 'slack', rather than the parts of the car which were specifically designed for this purpose. A chassis that flexes may be prone to fatigue and further "softening" with use will eventually result in failure. Cars of a sporting nature are, therefore, often very 'stiff', while convertibles or cabriolets are not often considered to be good candidates for high-performance sports cars because of their lack of a rigid roof.
Although, for some time, body flex was a result of attempts to keep a car's weight down, makers such as Audi
Audi
Audi AG is a German automobile manufacturer, from supermini to crossover SUVs in various body styles and price ranges that are marketed under the Audi brand , positioned as the premium brand within the Volkswagen Group....
(the A8
Audi A8
The Audi A8 is a four-door, full-size, luxury sedan car manufactured and marketed by the German automaker Audi since 1994. Succeeding the Audi V8, the A8 has been offered with front wheel drive or permanent four-wheel drive, with multitronic or tiptronic automatic transmissions — and in short- and...
), and Jaguar
Jaguar (car)
Jaguar Cars Ltd, known simply as Jaguar , is a British luxury car manufacturer, headquartered in Whitley, Coventry, England. It is part of the Jaguar Land Rover business, a subsidiary of the Indian company Tata Motors....
(with the 2003 XJ8
Jaguar XJ
Jaguar XJ is the designation that has been used for a series of luxury saloon cars sold under the British Jaguar marque. The first XJ was launched in 1968 and the designation has been used for successive Jaguar flagship models since then. The original model was the last Jaguar saloon to have had...
) have employed the use of aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
in chassis production to get around this obstacle, ensuring the weight of these cars and their level of body flex can both be kept to a minimum.
Typically, the stiffness of the body is measured in torsion. The body is supported at the spring caps at the rear, and then a torque is applied to the front spring caps via a long beam and a fulcrum. Values achieved range from 1000 lbft per degree for pre-War racing cars, up to 25000 lbft per degree for some modern production vehicles.