What Transmission Is in a 2000 Honda Civic Si?
The 2000 Honda Civic Si (EM1, U.S./Canada market) came exclusively with a close-ratio 5-speed manual transmission, factory-designated S4C, paired to the B16A2 engine; it did not offer an automatic or a factory limited-slip differential. In enthusiast and parts catalogs, you may also see Y21 mentioned in relation to similar B-series gearsets, but the U.S.-market 2000 Si’s original equipment is the S4C.
Contents
Factory Specification and Context
Honda positioned the 1999–2000 Civic Si as a high-revving, driver-focused model. Its standard and only transmission was a close-ratio 5-speed manual engineered to keep the B16A2 in its VTEC powerband. The unit uses a hydraulic clutch and a 4.40 final drive, favoring responsiveness over highway revs. Unlike Type R models of the era, the Si did not receive a helical limited-slip differential from the factory in the U.S. or Canada.
Transmission Codes and Market Variations
Honda’s B-series gearboxes are identified by stamped case codes. For the 2000 Civic Si, the original equipment code is S4C. Some similar B-series transmissions—most notably Y21 and certain S4C variants—share close gear stacks, and limited-slip versions existed in performance models overseas (e.g., Civic Type R), but those LSD units were not standard on the North American Si. Replacement or swapped units over the past two decades mean an individual car could wear a different code today, even if it began life with an S4C.
Typical Gear Ratios for the 2000 Civic Si (S4C)
The following list outlines the commonly cited factory gear ratios for the U.S.-market 1999–2000 Civic Si’s S4C transmission. These ratios emphasize acceleration and midrange pull, complementing the B16A2’s high-revving character.
- 1st: 3.230
- 2nd: 2.105
- 3rd: 1.458
- 4th: 1.107
- 5th: 0.848
- Final drive: 4.400
While minor sourcing discrepancies can appear in community literature, these figures reflect the accepted baseline for the EM1 Si’s U.S.-spec S4C gearbox without LSD.
How to Confirm What’s in Your Car
Given the age of these cars and the popularity of swaps and rebuilds, it’s wise to verify the transmission code on the case rather than relying solely on model-year assumptions. The following steps can help you confirm what’s installed.
- Locate the transmission stamp: Look for an alphanumeric code (e.g., “S4C-xxxxx”) cast/stamped on the bellhousing or top/front of the case near the engine-starter area.
- Check for hydraulic hardware: The EM1 uses a hydraulic clutch; verify the clutch master cylinder and slave cylinder are present and connected.
- Cross-reference the code: Compare the stamped code with reputable Honda parts catalogs or enthusiast databases to confirm gearset and LSD status.
- Inspect for LSD (if in doubt): With the car safely lifted, slowly rotate one front wheel by hand in neutral; opposite-direction rotation can suggest an open diff (stock Si), while same-direction movement can indicate LSD—though this is not a definitive test.
These checks help separate factory specification from later modifications, ensuring accuracy for maintenance, parts ordering, or performance planning.
Why It Matters
Knowing the exact transmission matters for sourcing the correct clutch kit, fluid, sensors, and synchro components, as well as predicting performance characteristics. The Si’s close ratios and 4.40 final drive contribute to its lively feel—one reason the EM1 remains sought-after among enthusiasts. If you discover a non-original gearbox, gear ratios or differential type may differ, altering drivability.
Bottom Line
The 2000 Honda Civic Si left the factory with a hydraulic-clutch, close-ratio S4C 5-speed manual (no automatic, no factory LSD in North America). Over time, some cars may have Y21/S4C swaps or aftermarket LSDs, so a quick case-code check is the best way to be certain of what’s in your specific car.
Summary
Original equipment for the 2000 Civic Si is the S4C 5-speed manual transmission with a 4.40 final drive and no factory LSD in the U.S./Canada. Typical ratios are 3.230/2.105/1.458/1.107/0.848. Because many EM1s have been modified or repaired, confirm by reading the stamped transmission code on the case.
What transmission does the Civic Si have?
6-speed manual transmission
Powered by a turbocharged 1.5L 4-cylinder engine paired with a close-ratio 6-speed manual transmission, the Civic Si provides a perfect balance of power and agility.
What kind of transmission does a 2000 Honda Civic have?
Honda Civic (sixth generation)
| Honda Civic Sixth generation | |
|---|---|
| Transmission | 5-speed manual 4-speed automatic CVT – HX only |
| Dimensions | |
| Wheelbase | 103.2 in (2,621 mm) |
| Length | 4,178 mm (164.5 in) (1995-98 hatchback) 4,171 mm (164.2 in) (1999–2000 hatchback) 4,448 mm (175.1 in) (coupé/sedan) |
What year Civic Si has a K20Z3?
K20Z (i-VTEC)
| Engine | Application | Rev limiter |
|---|---|---|
| K20Z2 | 2006–2010 Honda Civic (SEA) | |
| K20Z3 | 2006–2011 Honda Civic Si | 8300 rpm |
| 2007–2010 Acura CSX Type S | 8300 rpm | |
| K20Z4 | 2007–2010 Honda Civic Type R ( EDM ) |
What is the spec of the 2000 Honda Civic Si?
The Civic Si is powered by a DOHC 1.4L inline-4 VTEC motor which is paired with a 5-speed manual transmission. The motor produces 160 horsepower and has been left in a stock configuration. The exterior is finished in a very clean Flamenco Black Pearl. Complementing the black paint is 15-inch brushed alloy wheels.
