Crank/Balancer Bolt

The Chevrolet Performance Crank/Balancer Bolt (Part Number 12557840) is a precision engine fastener engineered for GM LS-series powerplants, including LS1, LS2, LS3, LS6, and L92 variants. This 16mm x 2.00 thread bolt measures 4.055 inches in length with a hex head design and is constructed from steel with a zinc oxide finish for corrosion resistance. Purpose-built for securing the harmonic balancer to the crankshaft, this OEM-specification fastener ensures proper damping of crankshaft oscillation and maintains critical engine timing integrity across high-RPM operation and demanding load scenarios.

The 4.055-inch length and 16mm diameter are critical specifications that prevent cross-threading and ensure flush seating against the balancer hub. Zinc oxide plating provides adequate protection against typical engine bay environments while maintaining the torque specifications required by GM engineering standards. The hex head design enables straightforward installation with standard socket tools and allows torque-wrench verification during assembly or rebuild operations. Users rebuilding or servicing LS-series engines—whether for street performance, track use, or restoration—depend on OEM-specification fasteners like this to avoid costly timing issues or balancer slippage that can result from undersized or incorrect substitutes.

This bolt is essential for engine builders, performance shops, and engine rebuild technicians working on LS-platform engines. Whether performing a complete overhaul, replacing a worn balancer, or assembling a stroker or crate engine, sourcing the correct crankshaft fastener eliminates guesswork and reduces the risk of assembly errors. Sold individually, this fastener allows builders to replace worn hardware or stockpile critical fasteners for multi-engine projects. Chevrolet Performance OEM parts are manufactured to exact specifications and carry the engineering validation of GM's performance division, making this bolt the standard choice for builds requiring reliability and consistency.