Spec Steel Single Mass Flywheel 6-Bolt Non-SAC SB53S-3 – BMW 335i (N54)

OVERVIEW

SPEC billet flywheels are CNC manufactured on-site to a .001 in. tolerance, against an industry standard of .010 in. That precision gives perfect balance and a perfectly flat bedding surface for the clutch disc, both of which also contribute to safety in competitive environments. All SPEC flywheels carry SFI certification.

The flywheel contributes to power transfer in three ways: it provides a consistent, friction-enhancing surface for the clutch disc; its weight sets the rotating inertia, which controls the ratio of power to acceleration and can make a car quicker or slower depending on gearing, tire, vehicle weight and where in the powerband the output arrives; and it must run true at rpm, with no dimensional runout to produce vibration. SPEC builds flywheels in high-carbon billet steel and aircraft-quality billet aluminum to cover light and medium-weight options, and can advise on the moment of inertia best suited to a given car. SPEC billet flywheels are developed for specific driving environments and are not a one-fits-all lightweight flywheel — consult a SPEC representative for a recommendation.

SPECS

• Type: single mass billet flywheel
• Material: high-carbon billet steel
• Crank bolt pattern: 6-bolt (2/2009 production onward)
• CNC machined to a .001 in. tolerance (industry standard is .010 in.) for a flat clutch bedding surface and true balance at rpm
• SFI certified
• Billet construction — SPEC flywheels are built in high-carbon billet steel and aircraft-quality billet aluminum to suit specific inertia requirements
• Rebuildable, with a replaceable steel friction plate formulated for clutch bedding and holding power (aluminum and most steel units)
• Developed for specific driving environments — not a one-size-fits-all lightweight flywheel
• Clutch compatibility: for use with SPEC SB53x-2 / non-SAC clutch kits only.

PARTS INCLUDED

• 1x SPEC billet single mass flywheel
• Pressure-plate-to-flywheel bolts
• Complete kit as supplied by SPEC; see the installation instructions for the full bill of materials.

TECH RESOURCES

Additional Parts Required

• A matching SPEC non-SAC clutch kit is REQUIRED. For SPEC SB53x-2 clutch kits only. Matching kits: SPEC Stage 2 SB532-2, SPEC Stage 2+ SB533H-2, SPEC Stage 3+ SB533F-2, SPEC Stage 4 SB534-2 or SPEC Stage 5 SB535-2.
• Pilot bearing, release bearing and alignment tool come with the SPEC clutch kit — they are not supplied with the flywheel.
• Installer-supplied: new flywheel-to-crank bolts (BMW specifies single-use bolts), a flywheel locking tool and a torque wrench.
• When switching to a single mass flywheel some flywheel chatter or rattle is to be expected.

Installation

• SPEC does not publish a downloadable installation PDF for this flywheel — follow the instructions supplied with the flywheel and clutch kit.
• Installation requires removal of the transmission and should be carried out by a qualified technician. Use new flywheel-to-crank bolts and torque to BMW specification.

Notes

• Fits 6-bolt cranks from 2/2009 production onward. Confirm your production date with Speed Logic before ordering.

PART NUMBER

• SB53S-3

VEHICLE APPLICATIONS