SPEC BMW B58 F20 F22 F30 F32 SPEC-Design Single Mass Flywheel for M140i xDrive, M240i xDrive, 340i xDrive, 440i xDrive
Unlock sharper throttle response, faster revs and stronger, more consistent clutch performance with the SPEC-Design Single Mass Flywheel for BMW B58. Perfect for BMW M140i, M240i, 340i and 440i owners looking for a lightweight flywheel and clutch upgrade that delivers on-road and track performance. This SPEC single mass flywheel is engineered for the B58 engine platform and is designed to work exclusively with SPEC-Design clutches.
Why choose this SPEC single mass flywheel
- Non-SAC mechanism pressure plate setup for a lighter rotating assembly, higher rpm capability and increased clamp load.
- Billet, rebuildable flywheel with lightweight, low MOI design for rapid engine response and repeatable performance.
- Aluminium option shows exceptional gains, with up to 17 whp on an otherwise unmodified car.
- Steel option shows around 10 whp and offers greater gear resonance damping, which is quieter at idle with the pedal out than aluminium.
- Purpose-built for BMW B58 performance driving, track use and fast-road builds.
Important fitment note: This SPEC-designed single mass flywheel cannot be fitted to an OEM design clutch. It is for SPEC’s proprietary SPEC-Design clutch systems for the BMW N55 and B58 platforms.
Compatibility and fitment
- BMW 1 Series F20/F21 B58 M140i xDrive and rear-wheel drive
- BMW 2 Series F22/F23 B58 M240i xDrive and rear-wheel drive
- BMW 3 Series F30/F31 B58 340i xDrive and rear-wheel drive
- BMW 4 Series F32 B58 440i xDrive and rear-wheel drive
Spec-Design system coverage: This flywheel is for SPEC’s proprietary SPEC BMW N55 B58 E82 E89 E90 E92 F20 F30 SPEC-Design clutches, including 1M, 135i, M135i, M140i, M235i, 335i and 435i.
Steel vs Aluminium
Aluminium: Produced one of the highest wheel horsepower gains we have seen, 17 whp on an otherwise unmodified car. Ultra low MOI for rapid rev matching and snappy throttle response.
Steel: Produced around 10 whp. Additional damping of gear resonance for a quieter idle with the pedal out than aluminium, while still offering reduced rotational mass and improved drivability.
Real-world results from Nforcd
We have used this SPEC single mass flywheel on B58 builds and our customers have been delighted with the improved response, stronger engagement and consistency under spirited driving. A proven BMW B58 flywheel upgrade for M140i, M240i, 340i and 440i owners who want a lightweight, rebuildable performance flywheel that lasts.
Part numbers
- SBB58S-2 - Steel
- SBB58A-2 - Aluminium
Fitting and support
Professional fitting is recommended. For installation by Nforcd in Warwickshire, request a quote at Sales@nforcd.com.
Compatibility check
Before dispatch we verify fitment. Provide your registration number for UK cars or the last 7 digits of your VIN at checkout.
Manufactured by
SPEC
Warranty
SPEC lifetime warranty.
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