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Pelican Parts

Why do lightened flywheels rattle?

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6 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
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YOUR RESEARCHWhy do lightened flywheels rattle?

Leading reported evidence

Replace gearing, etc etc

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Performed · outcome unconfirmed · Original poster

He just got it back from the shop after all kinds of fun work, new bigger turbos, changed gearing, etc etc.

Why do lightened flywheels rattle?
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Leading evidence: 'Replace gearing, etc etc' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Replace gearing, etc etc' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.

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Run sachs stage 2 clutch disk and pressure plate

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Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.

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Performed · outcome unconfirmed

I am the guy referenced above with the Supercharged 997 and LWFW, and I am running a Sachs Stage 2 clutch disk and pressure plate, which does not have those springs, and my LWFW still clatters.

Why do lightened flywheels rattle?
Frequently discussed actions (2)

These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.

Replace gearing, etc etc

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that performed work without a confirmed outcome
1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Performed · outcome unconfirmed · Original poster

He just got it back from the shop after all kinds of fun work, new bigger turbos, changed gearing, etc etc.

Why do lightened flywheels rattle?

Run sachs stage 2 clutch disk and pressure plate

No successful repair reported for this finding.

0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Discussions that performed work without a confirmed outcome
1

0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.

0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.

Performed · outcome unconfirmed

I am the guy referenced above with the Supercharged 997 and LWFW, and I am running a Sachs Stage 2 clutch disk and pressure plate, which does not have those springs, and my LWFW still clatters.

Why do lightened flywheels rattle?
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6 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.

  • Pelican Parts: 1 discussions

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POST 1 / ORIGINAL POSTEROriginal post

I was out in my buddies 996 last night. He just got it back from the shop after all kinds of fun work, new bigger turbos, changed gearing, etc etc. Anyway when he idles the lightened flywheel sounds absolutely terrible. Rattles like crazy. Our friend with a supercharged 997, his does the same. I'm a pretty technical guy and have rebuilt all kinds of different engines, know the fundamentals and parts, etc, but I don't understand this. I'm sure someone here has the answer..please enlighten me.

POST 2Original post

The original dual mass flywheel does a great job of dampening all the noise from the transmission as well as adding torsional dampening between the crank and trans input shaft. The lightweight aluminum versions seem almost to amplify the noise coming from back there!

POST 3 / ORIGINAL POSTEROriginal post

So that's what it is, just transmission noise coming through that was normally dampened? It sounds terrible. lol. He stalled a couple times too. lol Between the lightened flywheel not keeping as much inertia and the taller first gear it drives like a different car. I don't know how much boost the thing is putting out now, but it goes like stink. I feel like my Lotus is a relatively fast car, but the low end grunt of that thing is other worldly. He would blow me away all day long. (I can still take him in the curves though )

POST 4Original post

I,ve been told the rattle is the LWF clutch disc which has springs on it. The dual mass clutch disc is solid without the small coil springs. The rattle goes away as soon as the clutch is engaged and takes up the play on the torsion springs.

POST 5 / ORIGINAL POSTEROriginal post

Indeed it does. As soon as the clutch in engaged, no rattle.

POST 6Original post

Quotes source post: 5609353

The spring-loaded clutch pressure plates are stage 3, or race plates. This is not the source of the clatter Keith is referring to, although they may contribute to some other sounds. I am the guy referenced above with the Supercharged 997 and LWFW, and I am running a Sachs Stage 2 clutch disk and pressure plate, which does not have those springs, and my LWFW still clatters. That's how I know that those springs are not the cause. However, I don't mind the sound of it in my car at all. Plus, people who know what the clatter is smile when they hear it- they know it means business. BTW, from outside the car, the clatter is more noticeable on the passenger side. My Porsche tech said he thinks it may be because the tranny case is thinner on that side- odd, eh? CATTMAN

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