Lightweight Flywheel Chatter - 986 Forum - The Community for Porsche Boxster & Cayman Owners

pecivil · 08-02-2007, 11:45 AM

I have the aasco fly and it has chattered fron day1. I also had clutch done, with new everything when it went in. My porsche mech who did it told me it would chatter before he did it. What exactly makes the noise he was not sure about. He said it is much better in boxsters than in 996's. In a 996 the transmission is between you and the engine, and in the box, the engine is between you and the tranny, this was his reason. My chatter is only noticable stopped at idle, you can hear it, but it isnt what I would call loud. But any "car guy" standing next to the car would immediately know something is up.

I did get a chance to hear a 996 with one in his shop, and it is MUCH louder inside the car than in the box.

I also know that in BMWs with lt wt flys there is chatter. I think it is just inherent to lt wt flys bolted onto cars designed for dual mass flys.

pecivil · 08-02-2007, 11:48 AM

also, I am pretty sure the reason the manufacturers went to dual mass flywheels in the first place was for smoothness and to reduce vibrations in the drivetrain from the drivers perspective. I think Porsche started using them on the 964 and 968.

Cloudsurfer · 08-02-2007, 08:22 PM

Regardless of the reason, I can understand why a 996 is louder than a 986 due to drivetrain layout. If the chatter really is "normal," I'll just live with it. Its not obnoxious, but it is noticeable.

Such is life....

Patrick

Rwc94303 · 12-30-2016, 07:58 PM

I know this thread is old but I know what the answer is: Transmission gears are rattling against their mated pairs. Removing the dual mass flywheel took away the isolation of crankshaft torsional vibration from the gearbox. At low engine speed compression strokes and then power strokes, slow and then increase crankshaft rotational speed markedly, causing gears in the transmission to bang forward and back against each other making this sound.

When you disengage the clutch (pedal down) the transmission is disconnected and the noise goes away.
Using a driven disc that has a spring hub is the best answer I know of to lessen this noise.

Hope this helps someone.
Randy