It's not the flywheel that causes chatter, it's the clutch.
If the flywheel has uneven friction charactoristics (hot spots and such), that will cause chatter. But on a correctly machined flywheel, the flywheel will not cause chatter.
Chatter comes from the clutch. if a clutch's friction disk has a high coefficient of friction and a not so even distribution of that friction, the clutch will chatter. So, puck style friction disks, while good for cooling and eliminating green fade on the clutch, they will chatter. Even a full face disk will chatter, including the stock one. To make this chatter less apparent to the user, they install a set of springs in the hub.
In other words, if you need ultra high torque handling capabilities, go with a solid hub 4-6 puck friction disk, with a high clamping force pressure plate. Under this is a solid hub 4-6 puck friction disk with a lower clamping force. under this is a full face friction disk with a sprung hub and a high clamping force pressure plate, under this is stock with the lower clamping force.
So basically (higher torque handling capability = greater chances of chatter)
Now, onto flywheels :-)
I have a GREAT knowledge of flywheels, and have used every type... standard 304 stainless, lightened factory, Chromoly, and multi-piece alluminum.
the lighter the flywheel, the quicker your engine will rev (both up and down), and more energy will be transfered to the wheels, but there are a couple drawbacks... a flywheel is designed to store energy, the heavier the flywheel, the more energy is stored. This stored energy does two things, first it smooths the engine and second it helps your car move off from a dead stop.
Smoothing out the engine... your engine has two forces that affect the rotation. The first is the power stroke, which "kicks" the engine into rotation, the next is drag, which tries to slow the rotation down. The flywheel uses it's stored energy to maintain rotation speed till the next "kick". The heavier the flywheel, the more energy stored to combat the drag and thus a smoother engine
Starting off from a stop. The energy stored in the flywheel is what helps to start you off from a stop... When you let the clutch out, the energy stored in the flywheel, is transfered through the transmission to the rear wheels to help you move off.
Thus, with a lightweight flywheel... the engine ("MAY") run slightly rougher on a 4 cylinder engine.... though on my past experiences with MR2s, Hondas, and Nissans, this has been a non-issue and was not noticeable. Also, you have to rev the engine slightly more when taking off from a stop because there is less energy stored in the flywheel.
Now, here are my experiences with light flywheels.
professionally Lightened and heat treated stock (customer used against my judgement) - exploded while reving in the garage, destroyed the engine block, transmission case, put a 8" round divet in the concrete floor, and a 3" hole in the roof 20 feet up. The only thing that kept the tuner in the driver's seat from being injured was that when the ring gear came apart, the part heading to the driver's seat hit the starter motor and bent into a roller coaster shape. It's pretty cool and I have a picture of it somewhere.
Light 304 Stainless - was OK... not much lighter than stock, but worked well
Fidanza multi piece construction... Light weight, reved well, has replaceable friction material.... However, the dowel pins on one customer car came out, rattled around the bell housing and destroyed the transmission case. On another car, the ring gear came off, and buzz-sawed through the tranny case destroying the case, wiring harness and some hard pipes. Through past poor experience, I will NEVER use nor recomend multi-piece flywheel designes, especially with different metals as they have different expansion rates with heat, which mean that they can work themselves loose and come apart. All the Fidanza supporters always say how they are safe because they meet SFI specifications... However the SFI also says that they can only be used with a scattershield in case they come apart.
Chromoly... Absolutely the BEST, light, strong, and last... and when the starter disengages, the flywheel makes this ringing sound that's pretty cool :-) They handle the heat well, they are single piece design, there really is only one drawback... they are expensive but worth it.
So, for a car under 450 ftlbs or so of torque (to the flywheel), I would recomend a chromoly flywheel with a full face, sprung hub friction disk and heavy pressure plate... ACT makes pretty good products, but they don't list anything for our car.... I'm going to give them a call next week to see what they can do.
