A process for preparing zirconium-cerium-based mixed oxides which comprises reacting an alkali with an aqueous solution of a zirconium salt containing 0. Steam is created utilizing heat of the exhaust system. The supporting surface is designed and arranged to directly contact the component after assembly without contacting the bush to transmit an axial force. The process finds a first set of relationships between the values at the distinct time points and the values at the reference time points.