Clutch Masters FW-340-SF Steel Flywheel BMW B58 340i 440i M240i 6-Speed Toyota

Vehicle Fitment

• 2016-2021 BMW 340i / 340i xDrive (F30) - B58B30 3.0L Turbo Inline-6, 6-Speed Manual
• 2017-2021 BMW M240i / M240i xDrive (F22 / F23) - B58B30 3.0L Turbo Inline-6, 6-Speed Manual
• 2016-2021 BMW 440i / 440i xDrive (F32 / F33 / F36) - B58B30 3.0L Turbo Inline-6, 6-Speed Manual
• 2023-present Toyota GR Supra (A90 / A91 MK5) - B58B30M1 3.0L Turbo Inline-6, 6-Speed Manual

Fitment Notes

• 6-speed manual transmission only - not compatible with 8-speed automatic ZF transmission-equipped models
• Replaces the OEM dual-mass flywheel (DMF) - the stock DMF is not retained; this is a single-mass steel replacement
• Confirm engine code is B58 before ordering - earlier 340i and 440i models may have used the N55 engine which requires a different flywheel
• Compatible with Clutch Masters FX100-FX500 single disc clutch kits; must be paired with a clutch disc compatible with a single-mass flywheel (dampened or rigid hub as appropriate)
• Clutch Masters recommends steel flywheel over aluminum for turbocharged street applications - the steel retains more rotational inertia to maintain boost between shifts; for track-only or maximum weight reduction, the aluminum FW-340-AL is also available

Features

• Lightweight single-mass steel construction - eliminates the OEM dual-mass flywheel's failure-prone rubber-damped internal spring assembly while delivering better rotational inertia than aluminum for turbocharged street use
• CNC machined in-house on Haas CNC lathes from US-sourced 1045 or 4140 billet steel - continuously checked against spec throughout the machining process
• Zero balanced - every flywheel is checked to ensure it spins 100% true with even weight distribution on all sides
• Black oxide coating - prevents surface rust over the life of the flywheel while giving the steel a distinctive black finish
• Laser engraved with Clutch Masters logo and part number for permanent product identification
• SFI certified - meets motorsport safety and performance standards for sanctioned racing bodies
• Reduces rotational mass versus OEM DMF for improved throttle response and faster revs while maintaining better boost response than aluminum for street driving
• Made in the USA by Clutch Masters

Specifications

• Part Number: FW-340-SF
• Flywheel Type: Lightweight Steel Single-Mass
• Material: 1045 or 4140 Billet Steel
• Finish: Black Oxide Coating
• SFI Certification: Yes
• Transmission: 6-Speed Manual
• Application: BMW B58B30 3.0L Turbo Inline-6; Toyota GR Supra MK5 B58B30M1

Included Components

• 1x Clutch Masters Lightweight Steel Single-Mass Flywheel (FW-340-SF)

Product Description

The Clutch Masters FW-340-SF is a lightweight steel single-mass flywheel engineered as a direct replacement for the OEM dual-mass flywheel in BMW B58-powered 340i, 440i, and M240i F-series models equipped with the 6-speed manual transmission, as well as the Toyota GR Supra MK5 with the B58 engine and 6-speed manual. The factory dual-mass flywheel uses rubber-damped internal springs to isolate driveline vibrations - but this design introduces significant rotational mass and wears out under performance driving, requiring expensive replacement.

The FW-340-SF replaces all of that complexity with a single-piece CNC-machined billet steel unit that is lighter, simpler, and far more durable. Clutch Masters specifically recommends steel over aluminum for turbocharged street applications: the additional rotational inertia of steel helps keep the engine on-boost between shifts where the lighter aluminum flywheel's rapid rev-drop would pull the turbo off boost. CNC machined in-house at the Clutch Masters facility from US-sourced 1045 or 4140 billet steel, zero balanced, black oxide coated, and SFI certified - ready to pair with any Clutch Masters FX100-FX500 single disc clutch kit.