A flexible seal assembly 10 is provided for a joint 12 having a first member 15 which is both pivotable about and axially movable along an axis 20 relative to a second joint member 16. The seal assembly 10 is disposed within an annular recess 22 of the first joint member 15 and includes an annular seal 30 of a flexible, wear resistant material and a metallic load ring 31. The seal has an axially movable sealing portion 34 with an annular seal lip 38. The load spring 31 is disposed behind the sealing portion 34 for urging and maintaining the seal lip 38 in sealing engagement against a sealing surface 22 of the second joint member 16. A rigid stiffener ring 40 is molded into the sealing portion 34 of the seal 30 and is of a construction and position within the sealing portion 34 to provide the sealing portion with an intervening wall portion 41 of the resilient material of the seal 30 separating the stiffener ring 40 from direct force transmitting contact with the load spring 31 to prevent wear and fretting of the load spring.