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Old 11-11-2020, 09:48 AM   #1
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This might be worth perusing.
Lightweight flywheel a bad idea?
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Old 11-11-2020, 12:12 PM   #2
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Oh sorry for my late repsons, thanks all for the good input!

It looks like the flywheel I was offered has gone so I need to find something else. A lot of talk about the Aasco alu-wheel. I also realize that I want a sprung clutch, to mitigate the ratteling. This car is mainly a street car but I want it to be competetive at the track too.

So, if I would go with the Aasco, do anyone know a sprung clutch that would fit? My car is the 986s 2003.

Also a question to yoou gues who responded about lifting heigt, the 20", do you mean the total clearance so that 20" jacks would be enough? Or do I need to lift it 20" higher than how it stands with the wheels on? Stupid questions I guess.

I know that itīs an increased risk, but wtf..
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Old 11-11-2020, 01:30 PM   #3
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Quote:
Originally Posted by Robert986 View Post
Oh sorry for my late repsons, thanks all for the good input!

It looks like the flywheel I was offered has gone so I need to find something else. A lot of talk about the Aasco alu-wheel. I also realize that I want a sprung clutch, to mitigate the ratteling. This car is mainly a street car but I want it to be competetive at the track too.

So, if I would go with the Aasco, do anyone know a sprung clutch that would fit? My car is the 986s 2003.

Also a question to yoou gues who responded about lifting heigt, the 20", do you mean the total clearance so that 20" jacks would be enough? Or do I need to lift it 20" higher than how it stands with the wheels on? Stupid questions I guess.

I know that itīs an increased risk, but wtf..
Do your best to ignore anyone who says there are documented cases of failed crankshafts due to lwfw. Everyone always says this, but when pressed to provide said documentation, it invariably comes back to "Jake Raby says..... blah blah blah". He has "documented" ONE such case, with untold countless other extreme modifications done to the motor, yet le laid blame on the LWFW. Of course he did...

JFP on this forum has also said he's seen several over his years. I respect JFP immensely, and so I believe him. but they aren't "documented" so that we can look at what the circumstances were surrounding the failure. At that point I have to chalk those up to the same ethereal whispers of something.

On the other hand, there are literally HUNDREDS of documented installations with nary a problem. Including my own.

FWIW: I did not bother with a damped pulley, as that negates to some extent the reduction of weight I just did on the flywheel. I'm running a lightweight alu underdrive pulley. I DID however have my new pressure-plate balanced with the Aasco flywheel. Both were "close" from the factory, but not exact.
Use the Sachs Stage 3 clutch. And expect to hear the gear-lash anyway, when the trans is warm.

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Old 11-12-2020, 11:02 AM   #4
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Now that I've got a little more time, I thought I'd give you a little more of a complete view on the LWFW.

Most of this debate centers around what the actual purpose of the flywheel is on this motor. On many motors, the flywheel acts as an external balancer. You balance it with the reciprocating assembly to offset the imbalance inherent in the reciprocating assembly. When the flywheel is replaced with a flexplate (in the case of an automatic trans, for instance) then a balancer is used on the front of the crank.

This is NOT the same as a harmonic damper. (By the way; we're damping harmonics with a damper; we are NOT dampening harmonics with a dampener. )

A harmonic damper is simply absorbing shocks which tend to become vibrations. A harmonic begins with an event and then it "oscillates" at a wavelength which tends to feed itself, increasing dynamically as it travels the length of the crankshaft. A damper absorbs that oscillation / vibration / harmonic. But here's the deal (Biden reference haha) an internally balanced motor like the M96 has very few opportunities for that harmonic to occur, and if it does, it's absorbed in the gear-pack pretty effectively. Maybe you could have an issue if you like sustained high-revs in neutral.... The Dual-Mass flywheel is neutrally-balanced (such as a dual-mass unit CAN be balanced). IF you neutral-balance your LWFW, then your motor remains balanced.

So everyone who tells you you need to "dampen" the motor if you remove the DMFW flywheel; hand them a spray-bottle and tell them to have at it.

Quote:
Originally Posted by Robert986 View Post
Oh sorry for my late repsons, thanks all for the good input!

It looks like the flywheel I was offered has gone so I need to find something else. A lot of talk about the Aasco alu-wheel. I also realize that I want a sprung clutch, to mitigate the ratteling. This car is mainly a street car but I want it to be competetive at the track too.

So, if I would go with the Aasco, do anyone know a sprung clutch that would fit? My car is the 986s 2003.

Also a question to yoou gues who responded about lifting heigt, the 20", do you mean the total clearance so that 20" jacks would be enough? Or do I need to lift it 20" higher than how it stands with the wheels on? Stupid questions I guess.

I know that itīs an increased risk, but wtf..

Last edited by maytag; 11-12-2020 at 11:04 AM.
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Old 11-12-2020, 04:24 PM   #5
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Maytag throws it down ... Don't believe the hype.

I'm just one data point with a seven year old Aasco flywheel/clutch combo in a 2.5 race car running 10 - 20 days a year.

No issues, except I think I now no why my seven year old clutch slips a bit when it gets hot. Age!

Glad I checked my notes.
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