BMW 3 Series E90 (2006-2011)

The factory BMW S65 dual-mass flywheel is engineered with comfort in mind, catering to the luxury-oriented expectations of the brand’s driving experience. Its design focuses on dampening drivetrain vibrations, smoothing out gear transitions, and minimizing harshness during operation. However, this refinement costs valuable performance. The dual-mass flywheel adds a substantial 27 lbs of rotational mass to the drivetrain, which significantly hinders throttle response and makes rev-matching feel sluggish and disconnected. Moreover, dual-mass flywheels are notorious for being a weak link in modified or high-performance builds and can prove costly to replace when they inevitably fail.

Our Single-Mass Lightweight Flywheel Conversion addresses all of these shortcomings with a purpose-built, lightweight, single-mass design that prioritizes performance. Weighing in at only 19 lbs., this design significantly reduces rotational mass, allowing your S65 to achieve its true motorsport potential!

Features & Benefits:

Precision machined from 4140 HT heat-treated chromoly steel for exceptional toughness, even wear properties, and increased durability.
Material quality promotes even wear across the entire friction surface, prolonging component lifespan.
Heat treated to HRC 28-32, tempered to relieve stress and improve dimensional stability.
Hardness improves component wear characteristics.
Black oxide coated for corrosion resistance on non-friction surfaces.
Precision balanced to exceed OEM specification (G16 spec to 175g-mm).
Specifically designed to work with S65 OE-architecture clutches.
Optimized step height maximizes clutch clamp load and offers a prolonged service life.
Performance:

8 lbs. lighter than the factory BMW flywheel!
OEM Dual-Mass: 27 lbs.
Turner Motorsport Single-Mass: 19 lbs.
Faster revs
Improved throttle response and acceleration
Allows for a more engaging driving experience and delivers a feeling of direct connection
Installation:

Flywheel Hardware: For added peace of mind, apply Blue or Orange Loctite when installing factory flywheel bolts that do not come with pre-applied threadlocker.

If you own an M57-equipped BMW, you already know this twin-turbo diesel powerplant is an absolute torque monster. What you might also know is that all that low-end grunt and high-compression diesel vibration wreaks absolute havoc on your accessory drive system.

From the factory, both the E90 335d and E70 X5 35d utilize a rigid alternator pulley. With each cylinder's fire, the crankshaft experiences a violent micro-acceleration. Because the alternator has a heavy internal rotor spinning at high speeds, it wants to keep spinning at a constant rate. When the engine suddenly slows down (even minutely between firing cycles), the alternator fights the belt. This constant tug-of-war results in extreme stress on your engine's belt-driven components. At best, it’s an annoying, unrefined chirp at idle; at worst, it’s a ticking time bomb for your expensive harmonic balancer.

To solve this issue, many enthusiasts choose to run a clutched alternator pulley (also called an overrunning alternator pulley). A clutched pulley allows the alternator to "freewheel" or coast when the engine slows down, completely isolating its rotational inertia from the belt drive to prevent component wear. While the N52's clutched pulley (12317560483) is a straight bolt-on, the offset is incorrect for the E90 335d's accessory drive. Thankfully, our engineers designed this zinc-coated spacer to provide the precise amount of spacing needed to perfectly align the new pulley with existing belt drive components.