Genuine Honda Product
Direct Factory Replacement Part
Fits DC Integra, EG/EK Civic, Del Sol, S2000, and NSX
Cap and Diaphragm Assembly

Description
Vehicle Fitment
Included

Honda OEM Clutch Master Cylinder Cap - DC Integra / EG/EK Civic / S2000 / NSX

You're looking at your clutch master cylinder reservoir and the cap's either missing or it's cracked and sitting there doing nothing. The plastic's brittle. It's been 25+ years of heat cycles. The cap cracked and you lost it or you just left it off because it looked like it wasn't doing anything anyway. Here's the problem. Without the cap your reservoir's exposed. Dust is getting in. Road grime is getting in. Oil vapor's getting in. Water's getting in. Your clutch fluid's getting dirty. Dirty fluid means air bubbles. Air bubbles in the lines mean your clutch pedal's going to go spongy on you. You're going to press the pedal and it's going to feel mushy. You won't be able to find the bite point. You're going to grind gears trying to shift because you can't control the clutch anymore. This is genuine Honda OEM part 46973-SD4-003. It's the cap that belongs on your clutch master cylinder. Comes with the white diaphragm seal already molded into it. Screw it on and you're done. Your clutch pedal firms back up. Your fluid stays clean. Stop driving around with an exposed reservoir.

Here's What Happens When the Cap's Missing or Cracked

The clutch master cylinder's a sealed hydraulic system but it needs to breathe. When you press the clutch pedal the piston moves and the fluid level changes. The cap's got a diaphragm built into it that lets air in and out as the level rises and falls. Without the cap the reservoir's just sitting there open to the world. Dust gets in. Oil gets in. Moisture gets in. The clutch fluid starts getting contaminated with particles. Those particles create friction inside the lines. Friction creates air bubbles. Air bubbles in a hydraulic system make everything spongy. Your pedal's supposed to be firm and responsive. Instead it's mushy. You can't modulate the bite point. You're over-engaging the clutch or under-engaging it because you can't feel where you are in the travel. You're grinding gears. You're stalling the car. You're frustrated because something doesn't feel right. The problem's been sitting right there the whole time. The cap's missing and the fluid got dirty. Replace the cap. The pedal firms back up. Everything works again.

Diaphragm's Already Attached - Just Screw It On

This cap's not a separate piece from the diaphragm. They're molded together as one unit. You're getting the cap and the seal in one shot. Screw it onto the top of the reservoir and you're done. No ordering a cap and a diaphragm separately. No trying to install a diaphragm inside a cap. It's all there. The diaphragm lets air pass through when the fluid level changes but it keeps contaminants out. That's the whole job. The diaphragm breathes so you don't get a vacuum inside the reservoir but it seals out dirt. Direct replacement. Same cap. Same function. Same job it's always done.

Replace It Now - Don't Mess Around With This

If your cap's cracked or missing don't wait. Replace it now. We've seen people try to fix a spongy clutch by bleeding the lines over and over. They're bleeding and bleeding and nothing's working. They're frustrated. They're spending hours on this. Then they finally look at the master cylinder and realize the cap's been missing the whole time. The fluid got contaminated because the reservoir was exposed. That's why bleeding doesn't work. The problem's not trapped air. The problem's dirty fluid. Buy the cap. Screw it on. Done. We've also seen people ignore a cracked cap for months. They figure it's not a big deal. Then one day the clutch pedal goes mushy and they're wondering what happened. The cap cracked. Dirt got in. Fluid got contaminated. Clutch went spongy. Six months of driving around with a cracked cap wasted. Don't ignore it. You see a crack replace it immediately.

Honda OEM - Not Some Cheap Knockoff

This is genuine Honda OEM part 46973-SD4-003. It's the cap Honda puts on at the factory. The plastic's the right durometer so it doesn't crack easy. The diaphragm's the right thickness and material so it actually seals. The threads match your reservoir so it screws on right. Aftermarket caps are out there. Some are fine. Some are garbage. We've seen cheap knockoff caps with diaphragms that don't seal worth a damn. The cap screws on but air still gets in. Dirt still gets in. The clutch still goes spongy. We've seen cheap plastic caps that crack easier than the Honda caps because the material isn't as good. We've seen caps where the threads don't match perfectly and they don't seal right when you screw them on. The cap's holding back atmospheric pressure and keeping your fluid clean. It's not where you cheap out with an Amazon knockoff. Buy the Honda cap. It fits. It seals. It lasts. You screw it on once and you're done thinking about it.

What You Get
- Honda OEM clutch master cylinder cap - part number 46973-SD4-003
- Plastic cap with white diaphragm seal molded in
- Genuine Honda - not aftermarket
- Direct replacement
- One cap per order
Fits These Cars
- 1994-2001 Acura Integra
- 1986-1995 Acura Legend
- 1991-2005 Acura NSX
- 1992-1994 Acura Vigor
- 1990-1996 Honda Accord (4 Cylinder)
- 1992-1995 Honda Civic
- 1996-1999 Honda Civic DX/EX/LX Sedan
- 2001 Honda Civic
- 1997-2001 Honda CR-V
- 1993-1997 Honda Del Sol
- 2000-2006 Honda Insight
- 1988-2001 Honda Prelude
- 2000-2009 Honda S2000
Note: Clutch master cylinder cap for DC Integra, EG/EK Civic, S2000, NSX, and other Honda/Acura models. Genuine Honda OEM part 46973-SD4-003. White diaphragm seal molded into cap (one piece). Screws onto top of clutch master cylinder reservoir. Cap lets air breathe while keeping dirt, dust, oil, and moisture out of reservoir. Missing or cracked cap causes contaminated fluid, air bubbles, spongy clutch pedal. Replace when cap cracked or missing. Don't ignore damaged caps. Direct replacement - screws on. One cap per order.
1994-2001 Acura Integra
1986-1995 Acura Legend

1991-2005 Acura NSX

1992-1994 Acura Vigor

1990-1996 Honda Accord (4 Cyl)

1992-1995 Honda Civic

1996-1999 Honda Civic DX/EX/LX Sedan

2001 Honda Civic

1997-2001 Honda CR-V

1993-1997 Honda Del Sol

2000-2006 Honda Insight

1988-2001 Honda Prelude

2000-2009 Honda S2000
(1) Clutch Master Cylinder Cap

Clutch Master & Slave Cylinders