This listing is for the special slotted end nut that retained the engine side magneto sprocket on those SOHC sports and competition models - fitted wtih the outer timing cover that had a Rev Clock Gearbox fitted. These are CNC machined by us in Stainless Steel.
Price is Each
This slotted nut - Norton original Part Number A11M/80 (M representing Manx) is to the original Norton design - that allowed the magneto sprocket nut to also a Rev Clock Gearbox. These nuts are CNC machinined/milled by us, using the correct imperial Hex spanner size, but are made in stainless steel.
The slot is the correct 'nice slide' fit for the original type (imperial) width spade end used on most Rev Clock gearbox's of that period - as well as the reproduction gearbox we also sell, shown in one of the photos.
It should be noted that over the years that the SOHC engine was produced - there were many fractional variations of 'fit for the inner and outer timing covers for SOHC engines - including the end float of the oil pump driving spindle (that the sprocket fits onto, also shown in the photographs). We have spent considerable effort with these nuts - trying to ensure that the slot and depth dimensions fit suitablly on a number of genuine inner and outer timing covers (remembering of course that the original outer timing cover with casting for rev clock drive was actually quite uncommon on road models, more often being fitted on competition models).
When fitting this type of slotted nut, it should be remembered that the thread on the nut is a normal 'RH - right hand' thread . . . therefore, when the engine runs and the slotted nut drives the rev clock gearbox - there will be a tendancy for the nut to unwind, unless held on tighty - THIS WAS THE ORIGINAL NORTON DESIGN. FYI, because of this - and to allow as much thread area as possible - this nut is intended to be fitted without a washer behind it and the mag sprocket
But because of the design features we mention above, and becasue there were so many fractional variations in fit on the inner/ouiter timing covers - it is the customers responsibilty to satisfy themselves that this nut is not fouling the covers in anyway - and is not forcing the gearbox spade end against the rev clock gearbox. It is also the customers responsibility to satisfy themselves they have secured the nut satisfactorily. Hopefully this should all go without saying. . . as was always the case when fitted originally, but in this modern world - we want to make this clear . . . do not order if you are not entirely comfortable in fitting this type of drive nut.
As a final FYI on fitting a rev clock drive type outer cover on SOHC engines - based on my own experiences over the years (but every customer must make their own mind up on fitting) - when fitting this type of nut, I normally use a modern 'threadlock' liquid on the thread and tap the nut up after fitting, to ensure it is tight and locked - but regularly check it for signs of it having untightened (there is an inevitable risk it can come loose). When fitting the outer timing cover, having fitted this type of spade nut, and ensuring the rev clock gearbox is a nice slide fit (and actually I have found original nuts where the slot is quite loose) - I try and centralise the outer timing as best I can visually first - but just loosely tighten the two outer timing cover screws finger tight, and check carefully the rotation of the engine does not 'lock' up the rev clock drive. If all seems ok - I then rotate the engine a few turns slowly, which helps 'centralise' the timing cover properly on the drive slot - before fully tighening the outer timing cover screws.
These nuts are not cheap when compared to the standard - non slot nuts - but the time to develop and additional milling op required reflect this.
As a final note - although OHV models were not normally fitted with rev clock drives on the outer timing cover - a number of customers have fitted modified covers for rev clock drives of late - either for racing or sports models. For those owners - this nut has the same thread as the OHV camshaft sprocket nut so could also be considered - but again, it is the customers responsibility to ensure suitable clearances exist etc.