Honda S2000 6-Speed
Problems and Cost

Every S2000, AP1 and AP2, uses a close-ratio six-speed with a very short, precise shifter mounted almost directly on top of the gearbox. Honda revised the transmission for the 2004 model year with different ratios and synchronizer changes, which is why owners argue about "early" and "late" boxes. Both versions share the same basic weak points, and both are well past the age where wear parts start to show.

The good news: the S2000 box is strong. Broken gears are rare on stock or mildly modified cars. What wears out is synchros, and what gets misdiagnosed is the clutch system around it.

Common S2000 Transmission Problems

2nd and 3rd gear grind

The signature S2000 complaint. A crunch going into 2nd or 3rd, most often on a fast shift near redline, and almost always worse in the first few minutes of driving. The lower gears use multi-cone synchros that do a lot of work matching speeds from 9,000 rpm, and they wear.

• Only when cold, fine once warm: mostly normal for an older S2000, made worse by tired fluid. Short-shift and take it easy for the first few miles. Our cold shifting guide covers why.
• Only at high rpm, warm: the synchros are starting to wear. It will slowly creep down the rev range.
• At any speed, any temperature: worn rings, or the clutch is not fully releasing. Check the hydraulics before you pull the box.

Rushing the shift is the main cause of synchro wear on these cars. The shifter is so short and precise that it is easy to beat the synchro. Our synchro wear guide explains how to confirm it.

Popping out of gear

Less common than grind, but it happens on high-mileage and tracked cars. Worn engagement teeth, worn detents, or worn forks let the sleeve walk out under load or on decel. Tired engine and transmission mounts and a worn powerplant frame bushing make it worse by letting the drivetrain move. Our popping out of gear guide has the full list.

Clutch delay valve

The S2000 has a clutch delay valve (CDV) in the hydraulic line to the slave cylinder. It restricts flow so the clutch engages slowly, which protects the driveline from a dumped clutch but makes quick shifts feel soft and can encourage riding the clutch. Many owners remove it or fit a drilled-out one. It does not cause a grind on its own, but if you are chasing shift feel, it is part of the conversation. Bleed the system properly any time you touch it.

Release bearing and clutch fork

A chirp or squeal that changes with the pedal is usually the release bearing, or the fork and pivot needing grease. A worn fork and pivot also reduce release travel, which lets the disc drag and makes the synchros look guilty. Replace the bearing, and inspect the fork and pivot with every clutch job. See our throwout bearing noise guide.

Shifter feel

The stock shifter is already short. Notchiness that is worse cold is the fluid and the synchros; slop at the knob is usually the shifter assembly bushings. An aftermarket short shifter does not fix a worn synchro, and a very short throw makes it even easier to beat the ring. Our short throw shifter guide covers the tradeoff.

Diff Noise vs Transmission Noise

The S2000 has a separate rear differential, and it makes its own noises. Sort them out before you buy anything.

• Whine that changes with road speed, not gear: differential, wheel bearings, or tires.
• Clunk on and off throttle: diff mounts, worn diff bushings, axle play, or engine and transmission mounts.
• Noise in neutral with the clutch out that stops with the pedal down: transmission input side.
• Noise only with the pedal down: release bearing or pilot bearing.
• Noise only in one or two gears: that gear set inside the transmission.

Change the diff fluid at the same time as the transmission fluid. Honda specifies a different oil for the diff than for the gearbox, so do not use one bottle for both without checking your manual.

Rebuild vs Used Unit

A used S2000 transmission is a gamble. You are buying a box with unknown mileage and unknown abuse, and the ones on the market often came out of cars that were tracked or crashed. If yours grinds only on fast, cold shifts, a used unit may be no better.

A synchro rebuild by a shop that knows Honda manual boxes is the better bet if your gears and hubs are healthy. Use genuine Honda synchros; the S2000 box is sensitive to ring quality. If you have the press and the patience, it is a rebuildable transmission at home, but it is not a beginner's box. Our rebuild kit buyer's guide covers what to replace. While it is out, do the clutch, release bearing and pilot bearing; a pilot bearing puller and a clutch alignment kit make that part easy.

Fluid

Honda specifies Honda MTF (Manual Transmission Fluid) for the S2000 gearbox. It is a thin fluid designed for Honda's synchros, not a thick 75W-90 gear oil. That is the factory answer and a perfectly good one. Many S2000 owners run Red Line MT-90 instead and report smoother cold shifts, while others find it no better than fresh Honda MTF. If you want a thinner aftermarket option closer to MTF viscosity, Royal Purple Synchromax is another choice owners try. Do not use GL-5 hypoid oil. Change it more often than the maintenance schedule says if you track the car. More in our gear oil guide.

What It Costs

Ballpark numbers; S2000 parts and used boxes have climbed as the cars have become collectible. For hard parts beyond a kit, our sister store CoreTransmissionParts.com carries more transmission parts.

FAQ

Why does my S2000 grind going into 2nd or 3rd?

Usually worn 2nd and 3rd synchros, made worse by cold fluid and fast high-rpm shifts. Check the fluid and bleed the clutch hydraulics first, since a dragging clutch causes the same grind. If it grinds warm at normal shift speeds, the synchros need replacing.

What is the S2000 clutch delay valve?

It is a restrictor in the clutch hydraulic line that slows clutch engagement to protect the driveline. Many owners remove it for quicker, more consistent engagement. It does not cause grinding on its own, and the system must be bled after it is removed.

What transmission fluid does an S2000 use?

Honda specifies Honda MTF. Many owners use Red Line MT-90 instead and report better cold shifts, while others stay with fresh Honda MTF. Do not use GL-5 hypoid gear oil in the transmission.

Should I rebuild my S2000 transmission or buy a used one?

If the gears and hubs are healthy, a synchro rebuild with genuine Honda parts is usually the better bet. Used units have unknown history and many came from tracked or crashed cars, so they often have the same worn synchros.

How much does an S2000 transmission rebuild cost?

A shop synchro rebuild typically runs roughly $2,000 to $3,500 including removal and installation. DIY parts for synchros, bearings and seals usually run $500 to $1,000 if no gears or hubs are needed.