Clutch Masters 725 Twin Disc Clutch Kit for B-Series B16 B18

Clutch Masters 725 Twin Disc Clutch Kit | B-Series B16 B18

When a single disc stops holding your B-series, this is the next step. The Clutch Masters 725 Series Twin Disc Clutch Kit is a 7.25" (184mm) twin disc built for drag-focused B16 and B18 builds, from a turbo B18C1 DC2 Integra to a B16A2 EM1 Civic Si that lives at the strip. Both versions ship with the steel flywheel in the box, so there's no separate flywheel purchase to plan for.

What It Is and Why It Works

Two 7.25" discs split the work one disc can't handle alone. Clutch Masters estimates the FX725 twin at roughly 700 lb-ft of torque, and they're upfront that every torque rating is a ballpark, not a guarantee. The smaller diameter assembly carries less rotating mass than a full-size single, so your B-series revs quicker, shifts faster, and stages more consistently at high RPM.

The cover is machined from billet aluminum and Type 3 hard anodized, with roughly 25% more tensile strength than a cast cover. Clutch Masters measured about .003" of flex in their billet cover where a cast or stamped unit can flex up to .030", so pedal input goes into moving the diaphragm instead of bending the cover. The QR quick release pressure plate uses three spring-loaded bolts to engage and disengage the pressure ring evenly, which Clutch Masters says cuts internal clutch noise and chatter by up to 50%. That's the feature that makes a race twin tolerable on the street.

You pick between two disc setups. The Street and Race version (TD7S) pairs one ceramic rigid disc with one fiber tuff rigid disc for friendlier engagement. The Race version (TD7R) runs two ceramic rigid discs for maximum bite. Both are rigid discs, so neither drives like a sprung street clutch.

Specs

Available Options

Fitment

Manual transmission B-series applications only. Clutch Masters also lists the 1.6L DOHC Civic through 2001, which covers the Canadian Civic SiR. If you're running a B-series swap in an EG or EK chassis, the clutch follows the engine and transmission, not the chassis, so this kit works with your swapped B16 or B18 hydraulic setup.

What to Know Before You Buy

Pick your stage honestly. The TD7R with two ceramic discs is the drag piece: it bites hard, engages like a switch, and will make traffic miserable. The TD7S trades a little holding power for engagement you can live with on the drive to the track. Both use rigid discs, so expect more noise and a firmer take-up than any sprung single disc, QR system or not. Clutch Masters says it plainly: this clutch handles occasional street driving, it's not built to daily.

The steel flywheel comes in the box, which is worth noting because the single disc 725 kits with an -X part number make you buy the flywheel separately. If you're chasing every last bit of rotating mass for a race-only car, Clutch Masters also makes a billet 6061-T6 aluminum flywheel version that carries an SFI 1.2 rating for NHRA, IHRA, SCCA and NASA classes; check your rulebook before choosing steel.

While the transmission is out, replace the release bearing (Clutch Masters sells the twin disc release bearing separately, it's not part of this kit) and go through your clutch hydraulics. A 700 lb-ft twin will expose a tired master or slave cylinder on the first hard launch. Clutch Masters also offers a flywheel friction lock that prevents the flywheel from fretting loose on the crank, cheap insurance on a high-RPM B-series. And if your build makes under about 400whp and sees regular street duty, an FX400 single disc will hold it and cost you a lot less hassle at every stoplight.