46 in addition an upstanding lip 48 projects into canal 46 from race structure 40 to increase the bonding surface area for the polymeric adhesive material of thrust ring 50 thrust ring 50 is configured to act as a conventional spring back bumper element to absorb the axial load exerted on shaft seal 10 when it is press fit onto axle shaft 16 during installation in accordance with a preferred embodiment of the subject invention thrust ring 50 is a machinable sacrificial structure configured to be partially sheared away during the break in period of shaft seal 10 more particularly the deflector ring 28 of wear sleeve 24 is configured to mechanically remove at least a portion of thrust ring 50 during break in to create a running clearance between the deflector ring 28 and the thrust ring 50 specifically deflector ring 28 has a generally planar surface 28 which is initially compressed against thrust ring 50 during installation and which through rotation during the break in period of the shaft seal functions to machine away a portion of the thrust ring by shearing action during the break in period there is an initial increase in start up torque due to the presence of the thrust ring 50 however after only a few revolutions of the wheel hub the torque applied to the shaft seal rapidly decreases as the thrust ring is machined away to create a running clearance in addition because the running clearance is created in a relatively short period of time there is not a substantial increase in frictional heat generation in the area of the thrust ring moreover during the break in period the temperatures at the interface between the thrust ring and the deflector ring will remain well below the melting point of the.