Boxster S Clutch - what stage?

[JFP in PA]

Funny, I never said ANYTHING about your cherished light weight flywheel…….

"A dual-mass flywheel (DMF) is a rotating mechanical device that is used to provide continuous energy (rotational energy) in systems where the energy source is not continuous, the same way as a conventional flywheel acts, but damping any violent variation of torque or revolutions that could cause an unwanted vibration. The vibration reduction is achieved by accumulating stored energy in the two flywheel half masses over a period of time but damped by a series of strong springs, doing that at a rate that is compatible with the energy source, and then releasing that energy at a much higher rate over a relatively short time"

From a LUK white paper on DMF theory:

"The primary feature of the DMFW is the almost complete isolation of torsional vibrations."

"The DMFW permanently alters the vibration system of the crankshaft. In
the conventional system, the heavy flywheel including the clutch is rigidly
connected with the crankshaft. The large inertia of the flywheel generates
high reaction forces on the crankshaft.
The DMFW system behaves more favorably because the secondary
flywheel mass can be disregarded for the bending load. It is only very
loosely connected via the torsion damper as well as via the roller bearing to
the primary flywheel mass and therefore generates practically no reactions.
The primary flywheel mass is much lighter than a conventional flywheel and
is also elastic, like a flexplate for a torque converter.
Inherent bending and torsion resonance forms change with the DMFW in
comparison to a conventional system. The crankshaft is mostly relieved.
Figure 7 illustrates a measured example. Both torsion and bending
vibrations are lower with the DMFW. In individual instances, it must be
decided whether the crankshaft damper can be omitted or if a simpler
material can be used for the crankshaft, such as a casting."

Sure sounds like the people that make them believe other wise about what a DMF does...……..…...

[maytag]

Originally Posted by JFP in PA

Funny, I never said ANYTHING about your cherished light weight flywheel…….

Sure sounds like the people that make them believe other wise about what a DMF does...……..…...

Sounds to me like we're talking about a different type of dual mass flywheel. What LUK is describing there is a far cry from what's installed on the M96. Those types of dual-mass flywheels have been used on large-equipment motors for quite some time, and are in production cars recently because of the significant vibrations inherent in small 3, $ 4 cylinder motors with very small displacement, where the firing pattern doesn't allow for an even delivery of power. But even then, the number one concern is the transfer of that uneven torque / vibration / sound / harmonics to the driveline.

And as to your snarky comment about my "cherished" lwfw: that's how we GOT to this conversation, friend. And that's the only reason I can think of to ditch the comfort of a dual-mass flywheel. (can YOU think of another reason?)

there was really no need to get personal about this, JFP. we were being friendly. maybe a little sarcastic, hehe but friendly.

I think some of y'all have become very comfortable tossing-out "conventional wisdom", as if it were fact. I realize that's very common: the more something gets repeated without being challenged, the more it is just accepted as truth. The problem is that now you're offended when someone challenges it. I'm not being rude, I'm questioning because it's what I do: I'm a "disruptive innovator" by trade. If it doesn't make sense, then let's change how we're doing it. If conventional wisdom is right, then let's keep it. But if it doesn't hold-up to scrutiny, then let's put it back in the "needs further research" category. (or even the "myth debunked" category)

[JFP in PA]

Originally Posted by maytag

Sounds to me like we're talking about a different type of dual mass flywheel. What LUK is describing there is a far cry from what's installed on the M96. Those types of dual-mass flywheels have been used on large-equipment motors for quite some time, and are in production cars recently because of the significant vibrations inherent in small 3, $ 4 cylinder motors with very small displacement, where the firing pattern doesn't allow for an even delivery of power. But even then, the number one concern is the transfer of that uneven torque / vibration / sound / harmonics to the driveline.

And as to your snarky comment about my "cherished" lwfw: that's how we GOT to this conversation, friend. And that's the only reason I can think of to ditch the comfort of a dual-mass flywheel. (can YOU think of another reason?)

there was really no need to get personal about this, JFP. we were being friendly. maybe a little sarcastic, hehe but friendly.

I think some of y'all have become very comfortable tossing-out "conventional wisdom", as if it were fact. I realize that's very common: the more something gets repeated without being challenged, the more it is just accepted as truth. The problem is that now you're offended when someone challenges it. I'm not being rude, I'm questioning because it's what I do: I'm a "disruptive innovator" by trade. If it doesn't make sense, then let's change how we're doing it. If conventional wisdom is right, then let's keep it. But if it doesn't hold-up to scrutiny, then let's put it back in the "needs further research" category. (or even the "myth debunked" category)

DMF's come in many physical and mechanical configurations, the use of elastomeric separators like those found in the 986/987 DMF are just the latest and lowest cost variety, which is very common in modern passenger cars.

The white paper I referred to is just one of several available that trace the development and evolution of the concept from its first automotive use in 1985; it is hardly "conventional wisdom", but more an attempt to document the history, practical use, and end value of an idea from the first bent spring design to the current use of elastomeric materials.

To put an end to this as I can clearly see not interested in the background of why the DMF was developed and deployed, as well as what it was designed to do, just remember that there is "needs further research", and then there is what is called conformational bias, which implies disregarding whatever data does not fit a preconceived notion...….

Have a nice weekend.

[maytag]

Originally Posted by JFP in PA

......there is "needs further research", and then there is what is called conformational bias, which implies disregarding whatever data does not fit a preconceived notion...….

Exactly! Couldn't agree more! Persisting in a belief despite all data to the contrary.... crazy, ain't it? (Except the term is "Confirmation Bias". Confirm and Conform are two very different things)

You have a great weekend too!

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