Action Clutch Lightweight Flywheel for K20A/K20Z/K24A/K24Z

Action Clutch Lightweight Flywheel - Honda/Acura K Series (Chromoly or Aluminum)

Your K series already revs hard. A lightweight flywheel makes it rev harder. Action Clutch builds these in two versions - chromoly steel at 10 lbs and 6061-T6 aluminum at 7.5 lbs. Your factory K series flywheel tips the scales somewhere between 16-18 lbs. Drop 6-10 lbs of rotating mass and your engine responds to the throttle in a completely different way. Throttle blips are sharper, rev-matching is easier, and the engine climbs and drops through the RPM range noticeably faster. It's one of the most satisfying mods you can do on a K-swap or stock K series build.

That said, be straight with yourself about your use case. Lightweight flywheels make your car worse to drive in traffic. Low-speed clutch engagement gets trickier, idle is lumpier, and you'll need to rev more to pull away smoothly. If you're autocrossing, tracking it, or drag racing, that trade-off is worth it. If this is your daily driver and your commute is mostly stop-and-go, stick with stock or go chromoly if you want to split the difference.

Chromoly Steel (10 lbs) vs Aluminum (7.5 lbs) - Which One?

The chromoly flywheel is the smart call for most builds. It's one-piece chromoly steel with a heat-treated friction surface and an integrated ring gear - no pressed-on ring gear that can walk off under hard use. It's SFI 1.1 certified, so it's legal in classes that require certified components. You can also resurface it when the friction surface gets heat-checked, which means it actually lasts. At 10 lbs vs your stock 16-18, you're still cutting 6-8 lbs of rotating mass. That's substantial.

The aluminum flywheel is the choice when you want maximum rev response and weight savings. At 7.5 lbs, it's 2.5 lbs lighter than the chromoly version and up to 10.5 lbs lighter than stock. The body is CNC-machined 6061-T6 aluminum with a high-carbon alloy steel friction insert to handle clutch heat. It's made in the USA, dynamically balanced, and it has both 5-speed and 6-speed bolt patterns machined in. Just know that aluminum flywheels wear faster than chromoly. If you're running it hard on a dedicated track or drag car, budget for eventual replacement. For time attack, autocross, or street/strip builds where weight is a priority, it's the right pick.

Both versions are tested to 18,000 RPM - well above anything a K series will see in real life.

You'll Need a Type-S Clutch Kit

These flywheels use Type-S clutch dimensions. If your car didn't come with a Type-S transmission - RSX Base, EP3 Civic Si, first-gen TSX, Accord, or CR-V - you can't bolt your factory clutch to these. You'll need to run a Type-S clutch kit alongside it. Check the Competition Clutch Stage 2 Street Clutch for K20A2/Z1/Z3 or the Competition Clutch Stage 2 Kit for K20A/Z & K24A2/Z7 depending on your engine and power level.

If you're running a 2012-2015 Civic Si, 2009-2014 TSX, or 2013-2015 ILX, you also need an ECU flash with Hondata or KTuner after the swap. These cars have drive-by-wire and clutch engagement logic that the ECU monitors. Skip the flash and you'll get a clutch pedal warning light and potentially incorrect engagement behavior. It's a quick reflash - don't skip it.

The aluminum flywheel ships with the locating pins installed in the 6-speed position. If you're running a 5-speed, pull the pins and reinstall them in the 5-speed holes before you put it in. Takes five minutes and it's in the instructions.

What's in the Box

• Action Clutch lightweight flywheel - chromoly (10 lbs) or aluminum (7.5 lbs), your choice
• Chromoly: one-piece chromoly steel, heat-treated friction surface, integrated ring gear, SFI 1.1 certified, resurfaceable
• Aluminum: CNC-machined 6061-T6 body, high-carbon alloy steel friction surface, dynamically balanced, made in the USA, dual 5-speed/6-speed bolt pattern, locating pins included
• Both versions tested to 18,000 RPM

Fitment - Requires Type-S Clutch Kit

• 2002-2006 Acura RSX Base (K20A3)
• 2006-2011 Acura CSX Base (K20A3)
• 2002-2005 Honda Civic Si EP3 (K20A3)
• 2004-2008 Acura TSX (K24A2)
• 2003-2012 Honda Accord (K24, 5-speed)
• 2002-2006 Honda CR-V (K24A1)

Fitment - Requires Type-S Clutch Kit AND ECU Flash (Hondata or KTuner)

• 2012-2015 Honda Civic Si (K24Z7)
• 2009-2014 Acura TSX (K24Z3)
• 2013-2015 Acura ILX (K24Z7)

Direct Fit (No Additional Clutch Required)

• 2002-2006 Acura RSX Type-S (K20A2, K20Z1)
• 2006-2011 Honda Civic Si (K20Z3)