Wet disc brake

A brake arrangement for a vehicle adapted for connection to an axle end, said arrangement comprising a rotor disc adapted, in use, to rotate with said axle end and a stationary housing enclosing said rotor disc with one or more seals providing a substantially sealed zone within at least part of said stationary housing such that at least a braking effect region of said rotor disc, in use, passes through said substantially sealed zone, at least one friction pad located adjacent a braking surface of said rotor disc in said braking effect region so as to operationally engage said braking surface during a vehicle braking operation, the at least one friction pad including a friction material having a braking surface, said braking surface having grooves formed therein with at least some of said grooves having a leading end opening onto a leading edge of said braking surface and some of said grooves having leading ends spaced inwardly from an inner circumferential edge of said braking surface, said grooves having trailing ends opening onto one of an outer circumferential edge and a trailing edge of said braking surface, said stationary housing containing a liquid medium within at least said substantially sealed zone, wherein said liquid medium has a viscosity of less than 7 centistokes mm2/sec at 100° C.