Clutch Masters 725 Super Single Clutch Kit | K20 K24

If you're putting serious power through a K-series and the twin disc feels like overkill, this is the setup Clutch Masters built for you. The Clutch Masters 725 Super Single Clutch Kit is a 7.25" (184mm) race clutch for K20 and K24 manual transmissions, from a K20A2 RSX Type-S drag build to a K24 swap that lives at the strip. Heads up before you add to cart: this is the 08037-SD7R-X version, and the required 725 Series flywheel is sold separately.

What It Is and Why It Works

The 725 Super Single takes Clutch Masters' drag-racing twin disc platform and strips it down to one 7.25" race disc. Less rotating mass than a twin means the motor revs quicker, shifts feel faster, and you free up a little power that a heavier assembly would eat. Clutch Masters rates the Super Single at roughly 753 lb-ft of torque, and they're upfront that the number is a ballpark estimate, not a guarantee. Driving style and how much time the car spends at peak torque matter as much as the rating.

The cover is the reason this clutch works. Clutch Masters machines it from billet aluminum and Type 3 hard anodizes it. Their billet covers flex about .003" under load where a cast or stamped cover can flex up to .030", so every bit of pedal travel goes into engaging and disengaging the disc instead of bending the cover. That's what makes a race clutch this aggressive still feel consistent at the line, pass after pass.

This kit fits the small-bellhousing K-series 5-speed and 6-speed gearboxes in the RSX (DC5), EP3, FG2 and FA5 Civic Si, FB6 and FG4 Civic Si, CL9 and CU2 TSX, and the 2.4L manual Accords. It's pure racing hardware that tolerates occasional street driving, not the other way around.

Specs

Fitment

Manual transmission K20 and K24 applications only. The 2.4L ILX needs the 6-speed manual (the 2.0L ILX was automatic only). V6 Accords and the turbo K20C1 Civic Type R take a different clutch entirely.

What to Know Before You Buy

The flywheel situation is the thing that catches people. The -X in this part number means no flywheel in the box, and this clutch only works with a Clutch Masters 725 Series flywheel because the assembly is built around its specific dimensions. Your stock flywheel will not work. Clutch Masters makes them in steel (1045 billet core, black oxide treated) and aluminum (billet 6061-T6), both SFI 1.2 rated for NHRA, IHRA, SCCA and NASA competition. Budget for one or buy the version with the flywheel included. Sanctioned drag classes usually require that SFI-rated flywheel anyway, so pick based on your rulebook and how much rotating mass you want.

Be honest with yourself about how the car gets driven. A rigid 7.25" race disc engages hard and fast, with none of the take-up a sprung street disc gives you. Combined with the low rotating mass, it takes real footwork in traffic and it will chatter. Clutch Masters says it themselves: a race clutch on a street car wears fast and is unpleasant to live with. If your K20 or K24 sees commuting duty and the occasional track day under about 500 lb-ft, an FX350 or FX400 will hold your power and keep you sane. This kit is for the car that races and occasionally drives to the gas station, not the one that daily drives and occasionally races.

While you're in there, replace the release bearing and check the clutch master and slave cylinders, because a fresh race clutch shows every weakness in tired hydraulics. Grab a clutch alignment tool if you don't have one. And if you're between the Super Single and the twin disc, the twin holds a bit less by Clutch Masters' own estimates but is the more streetable of the two; the Super Single is the lighter, simpler drag piece.