With the amount of horsepower that the flat-four VW engine is capable of producing these days, the stock four dowel pin crankshafts just don’t have what it takes to keep the flywheel put. This drilling jig tool accurately indexes in the existing dowel pin holes providing a drilling fixture for an additional four holes. By drilling and doweling these extra four hole positions, you are giving your flywheel/crankshaft assembly twice the shear strength of the stock unit. It would take some extreme torque to shear this application. Works with 8mm Dowels.