It might surprise you to know that the A-Series engine has a vibration problem! But the factory has known it for years and designed a "dampener" to help absorb or counter balance this problem. The nature of the engine results in vibration that can result in crank bearing being knocked out! The uncomfortable feeling of the engine vibration is a problem, but losing the bearing can be a disaster. The most common dampener is a "one-piece" affair that is actually a pulley with a outer metal ring connected to it with a special vulcanized rubber. Great, simple design. But this same design has an inherent problem- as the rubber dries-up and/or is exposed to oil, dirt, etc. it cracks and stops "dampening". In severe cases this one piece affair has actually separated at the rubber resulting in all kinds of destruction! Check the back side of your dampener the next time you are in the engine bay- it could scare you!