Aasco flywheel is here.

[Jake Raby]

Originally Posted by insite

FYI, i was using the LWFW with a spring centered clutch. i'm pretty sure it wasn't a fractured crank, but i haven't opened the motor yet. the engine had 140k miles on it.

The material on the magnetic drain plug that you posted a few days ago look like rod bearing material to me.. This can be from a compromised crank that fractured at the radius of a rod journal and toasted that bearing. This is exactly what happened to Lon's engine, when he sent it to me he thought that it had lost a rod bearing, when it arrived I found the broken crank before I even disassembled it. Who knows, only a teardown will prove what the real cause is.

The sprung center disc only helps with harmonics and frequencies that are sent upstream through the input shaft from the drivetrain. The sprung center disc does nothing to aid in the harmonics generated by the engine that cannot be absorbed by the second mass of the flywheel after it has been removed and replaced with a single mass.

[Gilles]

Originally Posted by Jake Raby

The sprung center disc only helps with harmonics and frequencies that are sent upstream through the input shaft from the drivetrain. The sprung center disc does nothing to aid in the harmonics generated by the engine that cannot be absorbed by the second mass of the flywheel after it has been removed and replaced with a single mass.

Jake, can the loss of the dual mass flywheel be compensated with an UDP that has a harmonic balancer built into it? like the ones offered by RSS or ATI Racing..?

http://www.atiracing.com/products/dampers/damper_tech.htm your comments will be greatly appreciated.

Gilles, across the street from El Toro base...

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[Jake Raby]

Nothing makes up for the huge second mass positioned centrally between the engine and transaxle.

Everything helps, but nothing makes up for it completely.

if you were near El Toro in the early-mid nineties I was doing my part keeping you awake at night in those big Helicopters!

[mattatk]

Are you referring to chinooks?

[Jake Raby]

CH 46 Sea Knights.. Thats what I crewed and twisted wrenches on at Tustin and El Toro in my USMC days.

[07Prototype]

Newb chiming in...

After reading all of this it seems like the safest bet is to stick with an OEM\Factory flywheel but I would still like the assembly a little more performance ready. Jake you seem like the Guru here, have you heard of any problem with the Spec clutches offered or any better brands? I haven't been able to find any other companies offering performance clutches for 2001 986.

[thstone]

I am having a LWFW (and new clutch) installed right now. Should be done by tomorrow.

After reading through this thread (and others), there is no way that removing the DMFW and installing a LWFW can cause crankshaft failure. No how, no way. All production engines are factory balanced to the degree necessary (along with the proper design considerations such as bearing placement and type) to ensure proper and sufficient engine balance.

No engine is in perfect balance, no matter how much time and effort you put into it. Some engines can be in better balance than others but meeting the engine balance criteria to ensure long-term engine reliability is easily met by standard design and production methods.

Harmonics are a red herring in this discusion. Harmonics have very little energy unless a forcing function is driving at one of the harmonic frequencies. Yes, this can happen to a really old bridge in high winds but can't happen in a modern engine because the only forcing function in an engine is the cylinders firing which create the primary or fudamental frequency.

Beyond that, there's nothing in an engine (analogous to the wind in the bridge example) that would drive a harmonic with sufficient energy to cause catastrophic failure of the engine.

The DMFW is meant to reduce minor engine vibration from being transmitted to the body and interior (as part of NVH control), not to keep the engine from self destructing.