The FAQ you were looking for is here: www.honestjohn.co.uk/faq/dual-mass-flywheels/ There is nothing dismissive about simply stating a fact. Dual Mass Flywheels were developed to reduce vibrations in a four-cylinder diesel car's drivetrain and also to minimise torque reactions on 1st and 2nd gear. The problem is they do this by sandwiching two metal flywheels together with a compound, and that compound can fail, usually at between 40,000 and 80,000 miles depending on how the vehicle has been used. Many van fleets simply substitute solid flywheels and live with the vibration. But this would not be very pleasant in a car.