I am replacing some of the bolts attaching the gearbox outer cover to the gearbox shell. According to items I have read, the required bolt size is ¼"BSF, so I ordered some, which arrived today. Upon opening the package, it soon became apparent that the bolts supplied, as per my order were not correct. Despite the invoice stating they were the ordered ¼"BSF, the thread was much too fine. It looks more like BSCY to me. Are all boxes the same, or did, perhaps, Norton/AMC change the thread at some stage? My gearbox has the serial number NA6904 stamped on it, which I seem to recall from earlier observations, makes it about 1964 vintage.
It seems to me that the required bolts should have the same thread as the timing cover bolts on the engine. Any ideas, please?
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