A coupling assembly for use in transmitting force includes a housing which at least partially encloses a rotatable disc. The housing has a plate portion with an annular force transmitting surface which is engagable with the rotatable disc. A cooling fluid channel is at least partially defined by a side of the plate portion opposite from the force transmitting surface. A plurality of projections extend into a path of flow of cooling fluid through the cooling fluid channel. A cooling fluid inlet includes a passage having a portion with a large cross section connected in fluid communication with a radially outer portion of the cooling fluid channel. A portion of the inlet passage having a small cross section is connected in fluid communication with a radially inner portion of the cooling fluid channel. Ribs extend across the radially inner and outer portions of the cooling fluid channel.