A clutch assembly. The assembly includes a cover having a threaded inwardly facing surface and an adjusting ring having a threaded outwardly facing surface threadably received in the inwardly facing surface of the cover. The assembly also includes a pressure plate, a friction disc, a lever reacting against the adjusting ring to move the pressure plate into and out of engagement with the friction disc, and an adjustment mechanism. The assembly includes an elastically compressible seal assembly extending between opposing axially facing surfaces of the cover and the adjusting ring to prevent contamination from passing the seal assembly and accumulating on the threaded inwardly facing surface of the cover.