Audi has produced lightweight fibreglass reinforced polymer (GFRP) springs for its cars and, as owners of Ducati Motor Holding S.p.A., they could soon end up on their motorcycles.
Audi will fit the lightweight springs in an upper mid-size model before the end of the year. Light weight is crucial for car manufacturers to attain fuel economy targets set by authorities, but it is even more important in motorcycles for performance, so it stands to reason these springs will end up on future Ducatis, most likely the lithe Panigale.
The springs are a light green, the fibre strand is thicker than the wire of a steel spring, and it has a slightly larger overall diameter with a lower number of coils. Most importantly, they weigh just 1.6kg which is 40% lighter than conventional springs that weigh 2.7kg.
“The core of the springs consists of long glass fibres twisted together and impregnated with epoxy resin,” says Audi. “A machine wraps additional fibres around this core — which is only a few millimetres in diameter — at alternating angles of plus and minus 45 degrees to the longitudinal axis. These tension and compression plies mutually support one another to optimally absorb the stresses acting on the component. In the last production step, the blank is cured in an oven at temperatures of over 100-degrees Celsius.”
But it is the properties of the springs that make them ideal for motorcycles. “The GFRP springs can be precisely tuned to their respective task, and the material exhibits outstanding properties,” says Audi. “It does not corrode, even after stone chipping, and is impervious to chemicals such as wheel cleaners. Last but not least, production requires far less energy than the production of steel springs.”
Audi doesn’t explain how the springs are able to be more precisely tuned, but it would be a real benefit on a motorcycle where rider weight has such an impact on handling.
Also, the robust nature of the springs to rust, chemicals and stones would make them ideal on a motorcycle where the springs are visible and often part of the overall design aesthetics.