Norton Service Release Database N68

SERVICE RELEASE N68

NATURE OF RELEASE: Revised main bearings MODELS AFFECTED: All years and models of Commando DISTRIBUTION: Worldwide (General) EXPLANATION: We are introducing a new roller main bearing arrangement in production almost immediately. The fitting of this bearing arrangement reduces overall width between the main bearings and increases timing side main bearing journal diameter. For service purposes we shall in future supply only the crankshaft of the latest production size, part number 063106. To fit this to any Commando engine, the main bearings, part number 063114, must be used in conjunction. The new bearings are 2 dot single lip roller bearings and should be assembled with the lip into the crankcase in both cases. Main bearing 063114 is of the Ransomes type MRJ A. 30. Alternative bearings which may be used are listed below All bearings to be 2 dot or C2. Note in fitting that NJ type bearings have the rollers and cage assembled to the outer race so that the outer can be pressed into the crankcase either way round . The inner race must be pressed onto the crankshaft with the lip leading. The NF type bearings have the rollers and cage assembled to the inner race. The outer race must be pressed into the heated crankcase with the iip leading. The inner race complete with cage and rollers can be pressed either way round onto the crankshaft. The later crankshaft of reduced overall width is identified by the letter 'R' stamped onto the timing side crankshaft cheek adjacent to the bearing location. The designed crankshaft fitted end float for the new arrangement is 0. 010in to 0. 024in. (0. 254mm to 0. 6096mm). Alternative bearing types are illustrated below:   October 1971 Norton Villier Canada Limited