Your factory crank pulley is responsible for transferring energy from your crankshaft to your water pump, a/c compressor and alternator. It does this by way of a rubber belt and it does it’s job well. The drawback to the factory pulley is that it’s quite heavy. Reasons for this include less expensive manufacturing and using the pulley’s mass to smooth out ‘noise’ in the accessory system (NOT to be confused with functioning as a harmonic dampener, which it does not). The GrimmSpeed Lightweight Crank Pulley reduces the rotational mass of the system, allowing your engine to accelerate and decelerate the rotating assembly more quickly.
75% Reduction in Rotating Mass – weighs 1.1lb vs the 4.4lb OEM pulley
Machined 6061 T6 Aluminum – high quality, precision construction
Hard Anodized Finish – ensures a durable finish and resists corrosion
Removal Tool Mounting – allows the use of the GrimmSpeed Crank Pulley Tool
Factory Fitment – direct replacement for easy installation
The design process for this pulley ensured that a perfect factory replacement fitment was maintained while performance was maximized. It’s a common misconception that the mass of a crank pulley alone determines its effectiveness. The truth is that it’s actually the moment of inertia that affects the pulley’s ability to improve engine and throttle response. The moment of inertia, in non-engineering terms, is a function of not only the mass of an object, but how that mass is distributed about it’s rotational axis. A lower moment of inertia means that less torque is required to spin the crank pulley and, in turn, the crankshaft/engine. Our engineers took great care to keep the already minimal mass as close to the center of the pulley as possible without sacrificing its strength.
Another major improvement made is that you’ll find the necessary threaded holes to use our Crank Pulley Removal Tool for safe and easy installation and removal. On newer vehicles, cars can simply be put into a high gear to break the crank pulley bolt loose, but as with older chassis vehicles, this bolt will likely become quite stubborn with time. The use of the GrimmSpeed Removal Tool will make removal quick and easy.
Like any GrimmSpeed product, these pulleys are built to last. Using locally sourced 6061 T6 aluminum billet, the pulleys are machined and measured to verify critical dimensions before being anodized. The bright dip anodizing process that we use ensures a durable finish that will protect the pulley from corrosion. Lastly, each pulley is laser etched with a sharp GrimmSpeed logo.
2013+ Subaru BRZ
2015+ Subaru WRX
2013+ Scion FR-S