Powerbond Harmonic balancer hubs feature high strength and tough SG Iron AS1831-400-12/SAE J434D4512 (also known as nodular iron) for maximum strength. This is the same material used in most crank shafts and has much greater crack resistance. The crank bore size tolerances for Powerbond OEM balancers are tight (±0.015mm) to ensure the harmonic balancer fits the full range of OEM crank shafts to avoids a loose fit. All thread holes are set to the OEM thread size.
Cheap Asian sourced harmonic balancers are usually manufactured from weak, brittle “grey” iron to try and save money, however grey cast iron is prone to cracking resulting in irreparable damage. Most OEM replacement balancers use press inserted dampening rubber which can be prone to spinning and dislocation in high torque and serpentine belt applications. Harmonic balancers that use hot, pressure bonded dampening rubber can withstand much greater torque.