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VAC Motorsports ATI B58 Harmonic Crank Damper

by ATI

The ATI Super Damper will reduce wear on your engines rotating components, reducing the risk of catastrophic failure, therefore achieving more accurate valvetrain operation and lowering the risk of crank failure.

Completely unlike the rubber based dampers, this will automatically adapt to your modifications. It will then continuously self-tune in real time, as the engine revs up, torsional vibration suspends the inertia ring and reduces its weight felt on the crankshaft. Measured as rotating weight, this effect helps maintain quick revs while preserving optimum dampening. The ATI damper is a significant improvement on the proven elastomer damper configuration. A typical OEM style single-strip elastomer damper has an inertia weight (also called a ring) with a rubber insulator pressed to the crank hub. The inertia ring can move in relation to the hub when the elastomer material wears.

Replaces BMW part number 11238650741.


– Dampens torsional crankshaft vibrations at all RPM levels
– Protects against engine harmonics
– Direct replacement for the OEM unit
– Available with 21% Underdrive pulley shell (918351)
– Laser-etched timing marks
– SFI 18.1 Certified for competition use


– Shell Material: 7.074″ Aluminium, 6-rib
– Hub Material: Steel with inner shell 916501, bore 1.577″
– Inertia Weight: 1kg, 3 ring


– Compatible with BMW B58 series engines, including A90 Supra

Longer belt required, use length 1163mm