I have made a few posted relative to the affects of using a lightened flywheel in this forum previously and it seems that you guys could use a bit of information and clarification. Clatter is to be expected when moving from a dual-mass flywheel to a single-mass flywheel. This is due to the elimination of the dampening that is inherent to a dual-mass flywheel because of its design.

A dual-mass flywheel has two halves (planetary and secondary), and between these halves you will find torsion springs, cushions, and a bearing. These allow the flywheel-half that contacts the clutch disc to move or flex during use. Dual-Mass flywheels provide maximum isolation and frequency dampening of engine vibration, gear noise and engagement...but they also sap the transfer of power from the engine to the wheels because of their excessive weight.

Use of an aluminum or steel single-mass flywheel will have no harmful affect on a cars drivetrain. In fact, the lightened weight and lower MOI will actually allow for the rotating assembly to function with less effort. The gear noise that accompanies the use of a lightened flywheel is always present, even when using the original dual-mass flywheel. The difference is that the dual-mass unit masks this sound. There have been several folks on this forum that have seen gear noise develop even when using a dual-mass flywheel. This occurs when the OE flywheel's dampener stops functioning...and though this doesn't happen often, it happens. This will be more prevalent in cars that have drastic increased in torque output.

I hope this info helps. Let me know if you need anything else. Thanks,

 

Because there is still a lot more weight on drivetrain side including the flywheel and pressure plate. The flywheel acts as a damper though the dual mass unit is a far better damper. Every single "lightweight" pulley on the VQ market removes the dampening capabilities of the crank pulley. A lot of engineering goes into making those crank pullies crank dampers and the aftermarket companies fail to understand the intended purpose of the design. They say stupid things like "the motor is interally balananced" or "their pulley is perfectly balanced". These statements only prove their ignorance.

 

The biggest negatives with the lightweight flywheel are:

1) Noise

2) Reduced rotational inertia. If you remove rotational inertia, it makes it harder to put a device into motion. With a lightened flywheel, your car will be far more prone to bogging on the launch. Trey Hutchinson, the most avid drag racer on this site, has stated that his lightened flywheel consistently costs him 60' time because his car can't launch as effectively or consistently as one with a OEM flywheel.

The performance advantage of a lightened flywheel will not be seen in the 1/4 mile. If anything, you'll be slower. Road racing is where the advantage lies. When the car is operating at very high rpms, the lightened flywheel will make it easier to rev match downshifts and reduce chassis movement on the shifts.

 

Did you read the desription above? If he is right, going to a lightened flywheel removes much more dampening ability (and way more mass) then anything a light pulley would do.

 

I mentioned in my above post that MOI (Moment of Inertai) would in fact change. This will affect the way the car leaves from a stopped position but using increased RPM's at launch will help to counter this. Lower MOI is great for cars that spend the majority of their time in the mid to high RPM range. I personally run one of our Super-Twin clutch kits that has a total weight (including the clutch and flywheel) is 35-lbs. I like the feel of a lightened flywheel as it will allow the car to gain and loose RPM more effeciently. It will also, as a result of the reduced mass, allow you to more effeciently put the power to the wheels.

As a side note, SPEC offers a steel single-mass flywheel that has a weight closer to the stock dual-mass unit while providing the benefits of better engagement feel and less overall vagueness. This would be a great option for someone worried about reducing MOI. At any rate...I hope this info helps. Thanks!