An adapter assembly of a vehicle includes a bearing adapter configured to physically contact a bearing on an axle of the vehicle, and an adapter pad nested within an opening of a side frame of the vehicle and secured to at least one thrust lug of the side frame. The adapter pad includes a base section and legs depending from the base section. The legs are compressed between the at least one thrust lug of the side frame and shoulders of the bearing adapter to exert frictional forces on the shoulders of the bearing adapter. A combination of the frictional forces exerted by the adapter pad on the bearing adapter is less than a weight of the bearing adapter, such that as the side frame rises away from the bearing during movement of the vehicle, the adapter pad rises relative to the bearing adapter.