PMC Motorsport adapter plate / conversion kit / clutch kit Honda K20 K24 – 6-speed manual BMW N54 ZF GS6-53BZ 135i 335i 535i – 184 mm / 7.25" STEP (Ultralight Race)

Adapter plate designed to mate (swap / conversion) the Honda K20 / K24 engine with the ZF GS6-53BZ 6-speed manual gearbox from BMW N54 applications (E8x 135i, E9x 335i, E60 LCI 535i, Z4 35i), including the xDrive GS6X53BZ HGY version. Kit with Ultralight Race flywheel for 184 mm (7.25") STEP-type multi-disc clutches – the ideal solution for drifting, amateur, and professional motorsport.

Planning a Honda K20 / K24 engine swap into your BMW (E30, E36, E46, E34, E39, E90, E91, E92, E60, E61, E81, E82, E87)? Our adapter is a reliable solution. Replace the automatic transmission with a BMW manual gearbox and unlock new performance potential.

PMC Motorsport adapters not only enable automatic-to-manual conversions in Honda K20 / K24 powered vehicles, but also provide ideal solutions for Honda K-series swaps into BMW chassis and other platforms such as Nissan (S13, S14, S15, PS13) or Mazda RX-7 / RX-8.

The aluminum gearbox adapter plate is engineered to simplify gearbox installation as much as possible, eliminating radical modifications like cutting the bellhousing – only preparing the starter motor opening is required. Custom flywheels dedicated to PMC Motorsport adapters are manufactured from aluminum with a replaceable friction surface, fully inspected and dynamically balanced before dispatch. The Ultralight Race flywheel is designed for 184 mm (7.25") STEP-type clutches – modeled after Tilton OT-II Cerametallic 7.25" twin-disc (66-302xxx) and triple-disc (66-003xxx) pressure plates. Adapter thickness: 20 mm (0.78"). The small clutch diameter and low rotating mass ensure lightning-fast throttle response.

PMC Motorsport gearbox adapters are synonymous with precision and premium quality. The engineering process incorporates 3D scanning and CMM measuring arm inspection to deliver a flawless fit. High-precision CNC machining ensures perfect engine-to-gearbox concentricity, which is crucial for the longevity of the entire drivetrain.

Additional Information

Installation Manual

The gearbox adapter plate requires the use of a custom PMC Motorsport flywheel – in this kit, it is the Ultralight Race 184 mm (7.25") STEP-type flywheel matched to the ZF GS6-53BZ gearbox. Installing the flywheel requires Honda OE 90011-RBD-000 crankshaft bolts (not included in the kit), torqued to 118 Nm (87 lb⋅ft) using threadlocker. Mount the clutch fork on the lower release bearing position (if using a two-position release bearing), and shorten the gearbox guide tube (BMW OE 23 11 7 501 714) according to the diagrams below. The original Honda K20 / K24 starter motor (OE, not included in the kit) must be used.

Frequently Asked Questions

Which engines is this adapter compatible with?

With Honda K20 engines (K20A, K20A1, K20A2, K20A3, K20A4, K20A6, K20Z1, K20Z2, K20Z3, K20Z4) and Honda K24 engines (K24A1, K24A2, K24A3, K24A4, K24A8, K24Z1, K24Z2, K24Z3, K24Z4, K24Z5, K24Z6, K24Z7).

Which transmissions does this adapter fit?

With the 6-speed manual ZF GS6-53BZ gearbox from BMW N54 applications in versions HGX (THGX) – E9x 335i and E60 LCI 535i, JGD (TJGD) – E9x 335i, JGK (TJGK) – E82 / E88 135i and Z4 E89 35i – as well as the xDrive variant GS6X53BZ HGY (THGY).

Do I need to cut the gearbox bellhousing?

No. The adapter plate is designed specifically to avoid cutting the bellhousing – only preparing an opening for the starter motor is required.

Which additional parts do I need to complete the installation?

Honda OE 90011-RBD-000 crankshaft bolts and an original Honda K20 / K24 starter motor (OE). These are not included in the kit.

Which clutch fits the PMC flywheel?

The Ultralight Race flywheel is designed for 184 mm (7.25") STEP-type clutches. It was modeled after Tilton OT-II Cerametallic 7.25" pressure plates – twin-disc 66-302xxx and triple-disc 66-003xxx. The clutch discs must feature a 32.5x35-26N spline (26 teeth) for the ZF GS6-53BZ gearbox – e.g. Tilton 64185-8-VV-55 (twin-disc) or Tilton 64185-4-VTV-55 (triple-disc). Pressure plate, clutch discs, release bearing, clutch fork, and clutch slave cylinder are not included in the kit.

Does the gearbox require any modifications?

Yes. When installing a 184 mm clutch assembly, the gearbox guide tube must be shortened. Refer to the diagrams in the "Installation Manual" section for details.

Is this kit suitable for daily street driving?

No. The Ultralight Race flywheel paired with a multi-disc 7.25" clutch is engineered strictly for motorsport and drifting applications. For street and daily driven cars, we recommend our adapter version paired with a flywheel designed for standard BMW 240 mm pressure plates.

Which starter motor should be used?

The original factory Honda K20 / K24 (OE) starter motor. The starter is not included in the kit.

Is this adapter compatible with the ZF 8HP automatic transmission?

Yes. The PMC Motorsport adapter plate is universal and compatible with most BMW transmissions (applies to adapter plates manufactured after 2022). When converting to a ZF 8HP automatic transmission, the manual flywheel is replaced by a PMC Motorsport 8HP torque converter adapter.

What is included in the kit?

Aluminum gearbox adapter plate with mounting hardware, PMC Motorsport Ultralight Race 184 mm custom flywheel with replaceable friction insert, and pressure plate mounting bolts. Clutch assembly, release bearing, clutch fork, and slave cylinder are not included – they must be matched to your gearbox setup.

Can I purchase only the adapter plate or only the flywheel?

Yes. Every single component of the kit is available separately.

Does the price include customs duty for shipments outside the European Union?

No. Product prices and shipping quotes do not include import customs duties, taxes, or brokerage fees applicable in the destination country.

Can I buy with 0% VAT?

Yes, if you are a B2B customer outside Poland with an active European VAT number (verified via VIES) or if the order is shipped outside the EU.

Is the included manual sufficient to complete the entire conversion?

The manual provides the steps necessary to mate the engine and transmission outside the vehicle. Depending on the chassis, custom work may be required (mounts, crossmember, firewall or tunnel modification, driveshaft length). Professional installation is strongly advised.

Please note that a lightweight single-mass flywheel provides unmatched throttle response and engine acceleration by eliminating standard damping elements. This creates a direct drivetrain connection, which may result in natural and audible transmission gear rattle/gear chatter. This is an expected and characteristic trait of motorsport drivetrains resulting from the rigid mechanical coupling.