Clutch Masters 00+ K/Motor F/Transmission Aluminum Flywheel

Building a rear-drive K-swap with a Honda K20 or K24 in front of the S2000 six-speed and want the quickest-revving setup you can get? Clutch Masters FW-K2F-AL is the aluminum flywheel for that exact conversion, which the maker catalogs as K Motor to F Trans. It is the track-focused half of a two-flywheel family: the same K2F clutch kits also bolt to the steel FW-K2F-SF, and choosing between the two comes down to how the car is driven.

What this flywheel does in a K-series to S2000 conversion

No factory flywheel joins a K-series crankshaft to the S2000 clutch and release system, so the swap flywheel sets the clutch position for the F-series gearbox. Clutch Masters states that its K2F conversion clutch kits work only with FW-K2F-AL or FW-K2F-SF, so the flywheel and clutch are bought as one matched system.

Clutch Masters machines its aluminum flywheels in house from 6061 aluminum billet and Type 3 hard anodizes them. The clutch does not run on bare aluminum: the friction face is a separate insert, and Clutch Masters sells replacement inserts, so a worn face can be renewed rather than the whole flywheel being scrapped. The maker lists a 13.0 lb shipping weight for FW-K2F-AL, about 2 lb less than the boxed steel version.

Less rotating mass lets the engine pick up and drop rpm faster, which is what a road course or autocross car wants. The trade-off is drivability. Clutch Masters says it usually recommends steel over aluminum because aluminum flywheels can add gear noise, and it describes aluminum mainly as a race choice. Expect a bit more care pulling away from a stop and more audible gear rattle at idle than with the steel FW-K2F-SF.

Signs the flywheel needs attention

• Shudder as the clutch takes up, often from a glazed or uneven friction insert
• Slipping at full throttle in the upper gears even after a fresh disc
• Heat checking, scoring or hot spots on the insert face at clutch service time
• Loose or fretted flywheel bolts, or a flywheel that has walked on the crank flange
• A new K to S2000 build that needs a flywheel to make the conversion work at all

How to confirm before buying

With the transmission out, check the friction insert, the insert fasteners and the crank mounting face. A worn insert alone may only need a replacement insert; a cracked hub, damaged bolt holes or a flywheel that has spun on the crank calls for a new flywheel. Slipping under load should be checked properly before parts are ordered, and our slipping diagnosis guide covers reading rpm against road speed. If you are not sure whether a hesitation is a flare or a true slip, this guide on flare versus slip helps separate them.

Fitment

Clutch Masters lists FW-K2F-AL for Honda and Acura 2.0L K20 and 2.4L K24 engines from 2000 on, mated to the S2000 F-series transmission. It will not fit an S2000 still running its original F20C or F22C, a K-series with a front-drive Honda gearbox or a K-series on a Subaru transmission. For the Subaru gearbox swap use the FW-K721-SF flywheel. Mostly driven on the street? The steel FW-K2F-SF fits the same clutch kits. Adapter plates and bellhousings differ between swap builders, so send us your engine code and whose swap parts you used and we will check fitment first. More parts are in our clutch and rebuild kits section.

Install notes

• Clean the crank flange and flywheel mating face completely; aluminum is softer than steel, so any burr or debris can keep the flywheel from seating flat.
• Use new flywheel bolts, torqued in stages in a cross pattern to your swap kit spec. Clutch Masters offers a Flywheel Friction Lock, a hardened shim with an installed thickness of .010 to .012 in that it says stops fretting between crank and flywheel.
• Confirm the friction insert fasteners are tight before fitting the clutch, and center the disc with an alignment tool before snugging the pressure plate bolts evenly in a star pattern.
• If the build uses a crank pilot bearing, replace it; a pilot bearing puller removes the old one cleanly.
• Bleed the hydraulics and follow the clutch maker's break-in before any hard launches.

Will FW-K2F-AL fit a stock S2000 with the F20C or F22C?

No. It is only for a Honda or Acura K20 or K24 engine mated to the S2000 transmission. A factory-engine S2000 needs a standard S2000 flywheel.

What clutch goes with this flywheel?

A Clutch Masters K2F clutch kit. Clutch Masters says its K2F conversion kits only work with FW-K2F-AL or the steel FW-K2F-SF, so choose the kit level to match the engine's power.

Is aluminum or steel better for my K-swapped S2000?

Aluminum is lighter and revs faster, which suits track and autocross use. Clutch Masters notes aluminum can add gear noise and usually recommends steel for street cars, which is the FW-K2F-SF.

Can the friction surface be replaced when it wears?

Yes. Clutch Masters aluminum flywheels use a separate friction insert, and the maker sells replacement inserts with new flange nuts and socket cap screws.

Does it work with a K-series and a Subaru six-speed?

No. That swap uses the Clutch Masters FW-K721-SF flywheel. FW-K2F-AL is only for the S2000 F-series gearbox.

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