This listing is for the 'standard' length nut that fits both our Lucas and BTH magneto mounting studs on SOHC engines. This same nut can also be used on other motorcycle marques using either Lucas and BTH platform magnetos - but double check stud threads if you are not fitting them to our magneto studs (Item 1168 or 1169) - ours are 3/8" x 26tpi BSC thread, as most original magneto studs were from 1930's through to the 1950's.
These nuts are CNC manufactured to original dimensions and width of original magneto stud nuts (which can vary slightly over the years) with an overall depth of 9.5mm (deeper than most commercial nuts) - but if you look at our nuts you will see we have manufactured them with a slight lip to one face - this being the face that you screw the nut on to the magneto stud. The other side (the spanner side) has a normal chamfer. They are CNC bar turned from the correct suze imperial (Whitworth spanner size) hex stainless steel.
The reason for including a slight lip on these nuts - on Norton SOHC platforms, the stud fits through the crankcase timing side magneto platform (either an aluminium or magnesium alloy casting) - and although they should always be fitted with a washer under the nut - as they screwed on from underneath - if for whatever reason the washer drops away while undertaking magneto maintenance or adjustment, then the sharp hex edges of a normal type nut wont bite into the casting and damage the face with our type, or make tigtening more difficult.
As a final point - almost all Norton SOHC magneto's were mounted with just 3 studs (the fourth hole/stud on the platform magneto not being used on SOHC engines, as there was only provision for 3 studs) - for the two front studs - this type of nut was fitted, while the rearmost stud (as it fitted between the rear engine plates) was normally much longer (see our Items 1170 and 1171) - but both of these longer rear studs were also 'wasted' so their ends that make contact with the mag platform are not hex.
These nuts are CNC machined by us in stainless steel with the correct Imperial spanner size that was originally used on most Lucas and BTH magnetos. Note - this nut looks similar to some other 3/8" BSC Norton nuts we produce, but the depth and lip are specific to this nut type. However, there is no reason why this nut cannot be used on other Lucas/BTH platform mount magnetos for other marques. We recommend always fitting a washer when fitting these nuts - the Norton SOHC magneto platform specifically had machining under the platform to allow for this - to spread the load when the nut is tightened.
It is a shame they are hidden away under the platform mount really - because they are also a very pretty nut!
Price is Each.
Note - we also sell a SOHC Magneto Nut kit: consisting of 2 x this nut type, + 1 Extra long rear Magneto Bolt/nut + 3 washers, slightly cheaper when bought as a kit. This is Item 1170 for pre-Featherbed SOHC engines and Item 1171 for Featherbed models.
The last picture is taken from the 1948 Norton Spare Parts List and shows a BTH racing magneto - as fitted to competition SOHC models, with 3 studs, 2 standard length nuts (numbered 29 in the picture) and a Pre-Featherbed long magneto bolt/nut (our ITem 1170). But the same fittings are valid for Lucas Magdyno units on roadgoing Norton international and CS1 models.
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