the intermediate bearing 12 as it permits a degree of static displacement of the intermediate bearing 12 whilst accommodating the tolerances of the housing 2 and also assembly tolerances the flexible mounting 13 of the intermediate bearing 12 aids in accommodating the static displacement of the intermediate bearing 12 and the dynamic bending of the balance shaft 5 the balance shaft assembly 1 is provided with a lubricating system independent of the engine lubricating system and which is sealed into the balance shaft assembly the location of the lubricating system is generally indicated by the reference numeral 23 in particular a lubricating fluid can be sealed into the balance shaft assembly 1 for the life of the assembly 1 a transmission fluid can be employed as a lubricating fluid for example a small amount of lubricating fluid can be added to the assembly 1 before the front or rear end caps 8 9 are secured in place a completely sealed self contained balance shaft assembly 1 is therefore achieved that is lubricated for the life expectancy of the assembly 1 and which does not require periodic lubrication in use the lubricating fluid is deflected to the outside i e towards an inner face of the tubular housing side wall 3 due to the centrifugal force created by rotation of the balance shaft 5 passages of air at or near the inner face of the housing 2 are created due to the close location of the balance shaft 5 within the housing 2 thus the lubricating fluid is driven away from the shaft 5.