Honda K20Z3 Final Drive Gear 41233-RPT-010

Genuine Honda K20Z3 Final Drive Gear (41233-RPT-010)

This is the genuine Honda final drive gear from the K20Z3 transmission, the ring gear that sets your final drive ratio and transfers power from the transmission to the differential. It's the part you need when you're rebuilding a transmission, replacing a worn or damaged final drive, or installing a limited-slip differential, since an LSD bolts to this ring gear. Original equipment in the PNN3 transmission from the 2007-2011 Civic Si. Confirm your transmission before ordering, because the Si used two different final drives depending on year.

Confirm Your Transmission First

The most important thing on this page, because the 8th-gen Si used two different final drive gears and they're not interchangeable.

This gear (41233-RPT-010) is from the PNN3 transmission, the 2007-2011 Civic Si. If you've got a 07-11 Si or that transmission, this is your final drive.

The 2006 Civic Si Coupe is different. It came with the PNN4 transmission, which uses a different final drive gear, part 41233-PZF-020. That same PZF gear is also found in the K20Z1 (NSN4 transmission) and the K24A2 (ASU5 transmission). So if you're building a PNN4, K20Z1, or K24A2 transmission, you need the PZF gear, not this one.

The rule: match the final drive to your actual transmission, not just the chassis. A 07-11 Si (PNN3) takes this RPT gear; a 2006 Si Coupe, K20Z1, or K24A2 takes the PZF gear. Getting this wrong means a final drive that won't work in your transmission, so verify your transmission code before ordering.

What the Final Drive Does

The final drive gear (the ring gear) is the last gear reduction in the transmission, it's what the differential turns, and its ratio sets how engine RPM translates to wheel speed in every gear. It takes all the torque coming through the transmission and sends it to the differential and out to the axles.

You need a new one in a few situations: rebuilding a transmission where the original is worn, replacing a final drive damaged by a failure, or swapping to this ratio. It's also the gear a limited-slip differential mounts to, so an LSD install involves this ring gear directly.

Works With K-Series LSDs

Important if you're building the transmission with a limited-slip differential.

This final drive gear works with K-series limited-slip differentials, the LSD bolts to this ring gear. So if you're installing an LSD into your K20Z3 transmission, this is the compatible final drive, and the two go together as part of building a proper limited-slip setup. An LSD transforms how the car puts power down out of corners, and it mounts to this gear.

You'll Need Fresh Ring Gear Bolts

Don't reuse the old ones.

Whenever the ring gear comes off, for this final drive swap, an LSD install, or a rebuild, you need fresh ring gear bolts. They're torque-to-yield fasteners that stretch when torqued, so they can't be reused reliably. And note: if you're installing an LSD, you need the shouldered ring gear bolts (the higher-torque version), not the standard non-shouldered ones, even if your transmission didn't originally have an LSD. Ten bolts are required, so order a fresh set with this gear.

Fitment

Genuine Honda K20Z3 final drive gear, PNN3 transmission (2007-2011 Honda Civic Si). Part number 41233-RPT-010.

Not for the 2006 Si Coupe (PNN4), K20Z1 (NSN4), or K24A2 (ASU5), those use final drive 41233-PZF-020. Confirm your transmission before ordering.

If you're building or rebuilding a K20Z3 (PNN3) transmission, replacing a worn final drive, or installing an LSD in a 07-11 Civic Si, this is the genuine Honda ring gear for the job. Confirm you've got the PNN3 transmission, grab fresh shouldered ring gear bolts (and your LSD if you're adding one), and build the final drive right.