2004-2008 Acura TSX JDM K24A 6-Speed Manual Transmission AST5

About this unit

Transmission & Drivetrain Specs (AST5)

• Transmission Code: AST5

• Vehicle Application: 2004–2008 Acura TSX (First Generation, CL9)

• Type: 6-Speed Synchronized Manual

• Case Material: Cast Aluminum Alloy with Integrated Bellhousing

• Clutch & Actuation: Hydraulic, Push-type clutch system

• Differential Type: Factory Open Differential (Compatible with aftermarket upgrades like Quaife or MFactory limited-slip differentials)

• Recommended Fluid: Genuine Honda Manual Transmission Fluid (MTF)

• Fluid Capacity: 2.0 Liters (Fluid Change) / 2.2 Liters (Complete Overhaul)

Vehicle Fitment

• Acura TSX Base: 2004, 2005, 2006, 2007, 2008 (2.4L DOHC i-VTEC K24A / K24A2 Engine)

• Chassis Code Match: CL9

• K-Swap Compatibility: Highly sought-after manual transmission choice for older Honda and Acura chassis performance builds (such as Civic EG, EK, EF, and Integra DC2) utilizing K24 engine swaps.

USDM to JDM AST5 Transmission Swap Guide

Installing a JDM AST5 transmission into a North American (USDM) specification Acura TSX is mostly direct because the core bellhousing pattern matches the K24 block identically. Minor environmental and electrical variations require specific attention during the process.

Step 1: Pre-Installation Inspection & Seal Replacement

• Inspect the input shaft splines, throwout bearing sleeve, and axle seals for wear. Replace the transmission input shaft seal and rear main engine seal while the transmission is out of the vehicle to prevent future leaks.

• Ensure the gearbox is fully drained of shipping fluid before final installation.

Step 2: Switch and Sensor Transfer

• Unbolt the neutral safety switch and reverse light switch from your original USDM transmission and thread them onto the JDM AST5 housing if connector plugs show differences or weathering from overseas storage.

• Retain your original USDM vehicle speed sensor configuration to maintain correct dashboard speedometer output and prevent diagnostic trouble codes.

Step 3: Shift Bracket & Linkage Setup

• Remove the JDM select/shift arm bracket and install your original USDM TSX shifter cable bracket to ensure proper alignment with your center console gear shifter assembly.

Step 4: Clutch and Flywheel Alignment

• Inspect your clutch disc, pressure plate, and flywheel condition. If installing new or resurfaced components, torque flywheel bolts to factory specification using threadlocker and center the clutch disc with an alignment tool before pushing the AST5 housing flush against the engine block. Never draw the transmission flush using mounting bolts.

Step 5: Fluids and Testing

• Reinstall the intermediate shaft, half-shafts, starter motor, and structural mount brackets.

• Fill the unit precisely through the side fill plug with Genuine Honda MTF until fluid begins to level out of the fill hole, then torque both plugs securely.

• Bleed the hydraulic clutch system completely to clear all trapped air before starting the vehicle or shifting through gears.

What is included

You receive exactly what is pictured. Engines are supplied as a long block assembly with the components visible in the photos. Accessories such as the alternator, starter, intake manifold or sensors are included only where you can see them on the unit, so check the photographs before ordering and ask us if anything is unclear.

Before you order

• Confirm the engine code against your own vehicle, not just the model year.
• Japanese market units can differ from the US version in intake, loom and sensors.
• Replace the timing components, water pump and seals while the unit is out. It is cheap insurance on an engine this age.
• Keep your original accessories until the swap is finished and running.