This item listing is for a pair of complete rear wheel adjuster assemblies - with all parts patterned as per the original items, to fit Gardengate Plunger Norton Models. The 'Gardengate' was the plunger type spring frame that Norton adopted for all sprung models from 1939, through to the early 1950's an was offered for OHV and SOHC roadgoing singles, pre-Featherbed (Dominator) twins and the racing model Manx Nortons from 1939-50.
This assembly was designed specifcially to fit the alloy sliders fitted to that plunger frame - with the fabricated plates (referred to as 'Stirrups' in the Spare Parts List) designed to be a snug fit around either side of the castings, allowing the plunger type rear wheel spindle to pass through these adjuster plates, and the middle joining element of the plates holding pecial square headed threaded adjuster bolts, for adjusting the rear drive chain.
Both the head of the adjuster bolts and the central plate of the fabricated 'stirrups' are designed to be a snug fit in the wheel spindle slot of the castings, which stops the adjuster bolts from rotating when adjusting the chain tension with the rear nuts. Two other distinctive features of these assemblies are the large dished plates, which are designed to be a snug fit onto a corresponding shape at the end of the alloy castings (and although these look similar to the Norton petrol tank dished washers - they are actually slightly larger and a thicker gauge), and that each adjuster has two nuts - but the innermost main adjustment nut is for a larger (Whitworth) spanner than the second nut, which is designed as a locknut - to be untightened then tightened before turning the main nut to adjust the chain tension.
It should be noted that the main nut is specific to this application - being slightly deeper than commercially available 5/16^ nuts - no doubt because of the pressure being applied to pull the wheel assembly back, and was double chamfered (again, less common than other nuts of this period). Finally the adjuster bolts themselves have a more 'domed' appearance than standard 'chamfered' bolts - no doubt to reduce the chance of you scratching yourself or snagging them, when carrying out routine maintenance - all part of Norton's attention to detail.
Although a well designed and cosmettically attractive design - it is very common to find that original bikes fitted with the plunger suspension have now worn out these assemblies - common faults being that the fabricated stirrups have bent and rusted, the square head bolts have stripped their threads (or been replaced with normal bolts which do not work as well and not retained in place by the square), and of course the nuts have become rounded replaced with normal depth replacements. And of course - if you are building a Gardengate plunger model and dont have these already - they are now almost impossible to find at autojumbles
I am fortunate to have had a couple of 'New Old Stock' adjuster assemblies in my possession for many years unused (one of these being shown in the accompanying photographs), so was able to study the detail of the design closely - and have faithfully reproduced this in all elements of our assemblies.
The fabricated 'stirrups' are lasecut to the original design from steel, we then use a press tool for forming them to the correct profile before linishing and nickel plating (the original Norton finish, these will dull off in use).
However all other elements of the assembly are CNC produced in stainlesss steel and made specifically for these assemblies - so as well as being very pretty and durable, they will not rust. Also, the assemblies are pre-assembled in seperate bags with HM grease, ready to fit.
This item consists of two sets of assemblies, i.e. enough to fit for one motorcycle, however we also sell the dished plates, the bolts/adjuster nuts, and the nuts on their own as seperate items.
(as an aside - for the square headed adjuster bolts, the dimension of the 'square' is no longer commercially available in stainless steel, so instead we have to start with much wider 0.750" diameter round bar, then machine that down to the final 5/16" shaft, and then mill the square's onto the head in a seperate operation - one of the reasons theses assemblies are not cheap, and rarely re-manufactured by others).
Final Note - this assembly will not fit the rare 'Big Plunger' type spring frame offered in 1937-38 only, but as number of that frame were very limited, it is not expected many people will need adjusters for that type!