AST Suspension Lowering Springs (30mm/25mm TUV) - 2004-2011 BMW 6 Series 630i Cabrio/Coupe (E63/E64) YMM_1995_2004_BMW_5_Series_IV_E39 The diaphragm's four-stage heat-treating process

The diaphragm's four-stage heat-treating process enhances its fatigue resistance

Its adjustable design features precision-machined components that allow for accurate alignment adjustments

2 - Billet Aluminum Arm Assembled w/ FK Rod End

The Brass Plus 2100 Series Disc features a heavy-duty internal assembly that is engineered for high torque capacity

AST Suspension Lowering Springs (30mm/25mm TUV) - 2004-2011 BMW 6 Series 630i Cabrio/Coupe (E63/E64) YMM_1995_2004_BMW_5_Series_IV_E39 The diaphragm's four-stage heat-treating processAST Lowering Springs for the 2004 2011 BMW 6 Series (E63 E64) are manufactured from a premium high tensile chromium silicone wire which is handpicked by AST engineers for its quality and metal consistency. Each spring is cold wound and then heat treated to increase hardness and reduce internal stresses present after winding. Each spring is then individually shot peened, phosphate treated and then powder coated to outlast even the life of the vehicle.