The invention provides a seal for a rotatable shaft. The seal includes an inner case mountable to the shaft and having a body and first and second flanges extending radially outward from the body. The seal includes first and second sealing discs operable to seal against the first and second flanges of the inner case. The sealing discs are immovably associated with a housing spaced from the shaft. A spring encircles the shaft and inner case to urge the sealing discs against the flanges. The spring rate of the spring is controlled to enhance sealing, reduce turning torque, and extend life of the seal.