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Old 09-15-2012, 10:24 PM
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Fast Bob Fast Bob is offline
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Join Date: Jun 2004
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Mein Auto: 2004 330Ci ZHP 3 pedals
Originally Posted by numindast View Post
I'm a member of the uninitiated crowd, what makes an 8-lb flywheel "off road use only" as you said earlier? What does having an 8 lb 'wheel do to the driving experience?

As a slushbox owner I'm obviously not planning to do any such thing but I am still curious.
A flywheel serves a couple of acts as a big vibration damper, smoothing out engine pulses (not a BFD on BMW`s I6s, which have excellent primary balance). It also stores kinetic (rotational) energy, which make it easier to get the car under way from a standing start (a slightly heavier `wheel is beneficial here). When a manual trans is idling in neutral, all the shafts & gears are sort of banging around inside the trans case, because nothing is engaged or under load, so the (heavier) flywheel also dampens any potential rattling from the trans. An 8-lb. `wheel doesn`t offer much in the way of damping or centrifugal energy, so you will have more driveline noise, and the car will be harder to launch smoothly. Performance always involves a trade-off of some sort....a heavier flywheel (24 lbs. for the stock unit) gives acceptable levels of performance for non-enthusiasts, but is sluggish to react to change (remember Newton`s Third Law ?). A 16-lb. solid billet wheel is probably the best allows much faster rev capability, while providing enough inertial energy that the car isn`t a royal pain in the ass in everyday driving. And, the solid billet `wheel/sprung clutch combo offers a substantial improvement in engagement feel and predictability compared to the stock DMF/SAC setup.

Hope that was clear enough for ya....
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