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Lightweight Flywheels; (Any Disadvantages?)

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  • Lightweight Flywheels; (Any Disadvantages?)

    hi there,

    are there any disadvantages for having a flywheel thats too light on a street use car?

    also what are the differences of buying a lightweight flywheel and having the stock one machined for weight loss?


  • #2
    Hmm, off the top of my head, I guess a negative would be noise, well at least with my experience. My lighter flywheel made accel. a little louder, but faster

    One advantage of machining the stock flywheel would be that aftermarket ones are aluminium, and some cheap ones have been known to shear apart..


    • #3
      the flywheel is there to keep the vehical from stalling as easily. It purposely increases the rotating mass and thus the rotating inertia, giving your engine more power the moment the clutch is disengaged by "storing up" the energy from the engine.

      Basically, when the car is idling, some of the power from the engine goes into accelerating the flywheel up to speed, giving the flywheel rotating inertia (i dont remember the exact formulas... something like the power a rotating drum can provide is its inertial mass times the angular velocity (RPMS) ) The power that is being stored in the flywheel supplements the power from the engine when you engage the clutch, so if your sitting on a hill trying to get going from a start, the flywheel and engine will be helping you get started, not just the engine. It will also make engine braking less effective, because now there is less mass (and less inertial mass) for the wheels to have to spin, so theres less force applied to the wheels from the drivetrain, and less stopping power from engine braking.

      Now for the good... It reduces both sprung mass and rotating mass, so when you are accelerating (once in motion), your engine does not need to exert as much power to accelerate the flywheel, so that extra power goes to the wheels. Because of the lack of mass, engine response also increases (or at least the willingness to rev increases) There is of course less strain on the crank-shaft bearings and engine overall, but not enough to make a huge difference.

      Generally, from the factory, the flywheels can be a bit lighter, but you dont want to go way too far, cause then it will be pretty hard to get your car moving from a stop without destroying your clutch


      • #4
        is that y i stall sometimes after shifting into neutral after a high hard RPM?