Vibracoustic, a supplier of automotive vibration control technology, has developed a cord-reinforced elastomer coupling – named NRG Disc – for the new BMW Alpina B7 Bi-Turbo, one of the most powerful and fastest all-wheel drive sedans. Jointly developed with BMW, this new coupling is claimed to offer benefits in terms of durability and weight in comparison to other solutions available today.
Sports sedans are usually equipped with rear-wheel drive or all-wheel drive, meaning the propshaft is subject ed to very high strain: at speeds of 300km/h, it rotates around its own axis up to 7,500 times per minute. The torsional vibration occurring in the engine is transferred to the propshaft via the transmission, where it can cause noise and vibrations as well as damage the drivetrain. Typical symptoms include ‘clunking’ noises, declutch bumps, and gear rattle noises.
Hardy discs isolate torsional vibration occurring at the prop shaft. They also harmonize the torque ramp-up and compensate for the axial displacement and Cardan angle. Vibracoustic is breaking new ground in the BMW Alpina B7 Bi-Turbo with the NRG Disc (New Rubber Generation Disc), a cord-reinforced flexible coupling. With 447kW (608PS), 800Nm of torque and a top speed of 310km/h, the vehicle is very powerful, but through the use of specific cord packages for drive and overrun direction, different cord types, optimized winding processes and elastomer compounds, refinement is enhanced. The disc is also claimed to be 32% lighter and more compact than other series solutions available on the market.