Crank pulley Material: Hub: QT500-7; Inertia ring:HT250 ; RUBBER:NR 1.Elastomer(rubber): hardness 70-75 shore A 2. the complete in static balance shouldbe within 0.05kg/mm 3.slip torque: a torque of 390Nm is applied to the hub at any temperature between -40degree and 66 degree 4.No visible porosity allowed on the seal dia and pulley v's 5. Remove all sharp edges and burrs.