PRODUCT DETAILS
Competition Clutch Stage 4 Clutch Kit | K20 RSX, Civic Si
If you're pushing your 2002-2006 Acura RSX or 2002-2011 Honda Civic Si hard, the Competition Clutch Stage 4 (8037-1620) is the "I'm done with stock" move. Turbo, supercharger, nitrous, or a rowdy street and strip K20 build: this is the clutch you bolt in when you're done slipping through third and fourth. One thing up front so nobody's surprised at the box: the flywheel is not included, so plan on a new or freshly resurfaced flywheel in the same job.
What the Stage 4 Actually Is
The disc is a six-puck, torque-sprung setup with ceramic buttons, so it grabs hard and survives heat. Competition Clutch rates the Stage 4 at up to 250% over stock torque capacity, around 400 lb-ft at the wheels per the manufacturer, with roughly 1,700 lbs of pressure plate load behind it. Engagement is firm and direct, but the sprung hub damps the shock loads that an unsprung "on/off" disc feeds straight into your transmission, which is the difference between a race clutch you can drive to the track and one that lives on a trailer.
The kit comes as a full package: performance pressure plate, six-puck ceramic sprung disc, throwout bearing (where applicable), pilot bearing or bushing (where applicable), and an alignment tool. Everything except the flywheel, so you're not mixing random parts to complete the install.
Key Features
- Fits K20 engines in the 2002-2006 Acura RSX (K20A3 5-speed and K20A2/K20Z1 Type-S 6-speed) and 2002-2011 Civic Si (EP3 K20A3, FG2/FA5 K20Z3)
- Six-puck torque-sprung ceramic disc: aggressive bite with more streetable manners than an unsprung puck
- Up to 250% increase in torque capacity, approx. 400 lb-ft at the wheels (per manufacturer)
- 1,700 lb pressure plate load (per manufacturer)
- Includes throwout bearing, pilot bearing/bushing, and alignment tool
- Flywheel NOT included: pair it with a new flywheel or have yours resurfaced
- Recommended 300-mile street break-in for the most consistent engagement
Fitment
| Year | Make | Model | Trim | Engine |
| 2002-2006 | Acura | RSX | Base and Type-S | K20A3 / K20A2 / K20Z1 |
| 2002-2005 | Honda | Civic | Si (EP3) | K20A3 |
| 2006-2011 | Honda | Civic | Si (FG2/FA5) | K20Z3 |
K-series manual transmissions only. If you're K-swapped in an older chassis, this kit works with your K20 and its transmission; the chassis doesn't matter to the clutch.
What to Know Before You Buy
Sort the flywheel before the transmission comes out. A fresh ceramic disc on a heat-checked, glazed flywheel is how you get chatter and hot spots that no break-in will cure. Resurface your stock flywheel or grab a new one in the same order, and while everything's apart, look at the clutch master and slave cylinders, because a 1,700 lb pressure plate will find the weak spot in tired hydraulics.
Then break it in like you mean it. For the first 300 to 500 miles, stay out of full-throttle launches and high-RPM clutch dumps. Shift often, use light to moderate throttle, and let the disc seat into the flywheel and pressure plate. That's what gives you stable engagement and long life instead of hot spots and chatter. And be honest about the car: a six-puck ceramic disc on a bolt-on daily is more clutch than you need, and a Stage 2 or 3 will be far friendlier in traffic. This one is for builds that actually make the power. If you're unsure about setup or break-in, reach out and we'll walk you through what's worked on our own K20 builds.
| Year | Make | Model | Trim | Engine |
| 2002-2006 | Acura | RSX | Base and Type-S | K20A3 / K20A2 / K20Z1 |
| 2002-2005 | Honda | Civic | Si (EP3) | K20A3 |
| 2006-2011 | Honda | Civic | Si (FG2/FA5) | K20Z3 |
K-series manual transmissions only. If you're K-swapped in an older chassis, this kit works with your K20 and its transmission; the chassis doesn't matter to the clutch.
Before You Pull the Transmission
Sort the flywheel first. A ceramic six-puck disc is unforgiving of surface problems, so inspect your flywheel for heat cracks, hot spots, and runout before anything comes apart. If it's questionable, resurface it or replace it. While you're in there, check the clutch master cylinder and slave cylinder. A 1,700 lb pressure plate will find weak spots in tired hydraulics faster than a stock clutch ever did.
The Install
Standard clutch replacement procedure applies. Use the included alignment tool to center the disc before you torque the pressure plate bolts. Don't skip this step; an off-center disc makes the transmission input shaft fight the pilot bearing on the way back in, and it shows up as vibration later.
Break-In Period
Competition Clutch specifies a 300-mile break-in. For those 300 miles, avoid full-throttle launches, hard clutch dumps, and extended clutch slip. Shift often, keep throttle light to moderate, and let the disc seat evenly against the flywheel and pressure plate. That's what gives you consistent engagement and long service life. Rush the break-in and you're likely to get hot spots and glazing instead.
A Realistic Heads-Up
A six-puck ceramic disc has a firm, noticeably heavier pedal compared to stock. In slow traffic it's more work. If your car is a bolt-on daily and you're not making significantly more power than stock, a Stage 2 or Stage 3 will be friendlier to live with. The Stage 4 is for builds that actually need it.
Disc Specifications
The Stage 4 1620 Series uses a six-puck, torque-sprung ceramic disc. The sprung hub (torque-sprung) design is what separates the 1620 Series from Competition Clutch's rigid 0620 Series (part 8037-0620). If you're looking at both, the 1620 is the one with hub damping. The 0620 is stiffer and unsprung. These are different products.
| Spec | Value |
|---|---|
| Disc diameter | 8.500 in. |
| Input shaft diameter | 1-1/32 in. |
| Spline count | 24T |
| Disc type | Six-puck, torque-sprung, ceramic buttons |
Pressure Plate
Retailer listings, including Real Street Performance and Paradise Racing, cite a pressure plate clamp load of 1,700 lbs. Competition Clutch's own published material states a torque capacity increase of up to 250% over stock. An absolute lb-ft figure does not appear in Competition Clutch's own published specs, so treat any wheel-torque number you see elsewhere as a retailer-derived estimate rather than a manufacturer guarantee.
Part Numbers
The primary part number is 8037-1620. You'll also see it catalogued as CCX-8037-1620, COC-8037-1620, CC-8037-1620, and CCL-8037-1620 depending on the retailer. All of those point to the same kit.
Series Note
Competition Clutch calls this the 1620 Series. The sprung hub is the defining feature of that designation. If a listing shows 8037-0620, that's the unsprung 0620 Series, and it's a meaningfully different product in daily use.
- Performance pressure plate
- Six-puck torque-sprung ceramic disc
- Throwout bearing (where applicable)
- Pilot bearing/bushing (where applicable)
- Alignment tool
Flywheel is not included. Plan for a new flywheel or a freshly resurfaced stock unit in the same job. Putting a fresh ceramic disc against a heat-checked or glazed flywheel is how you get chatter and uneven wear that no break-in period will fix.