Square Head Manx Norton/M30 Type Clutch Spring Screw - Stainless Steel: Each

Product no.: 0881 A11M/403

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This is the distinctive square head, shouldered clutch spring screw as fitted to orginal Manx Norton and M30 competition 3 plate clutch's. These are identical in dimensions to the original screws, but CNC manufactured in Stainless Steel. 

Price is Each, 3 required per clutch.

An original Manx Norton square headed screw was used as the pattern to these (and actually double checked with a second set that had the same dimensions to ensure these were correct).  As you can see from the accompanying photographs these screws have a distinctive shoulder that means when fitted to the racing clutch (which is shallower than the standard roadgoing clutch and only has 3 friction plates fitted), ensures the screws can be fully locked down against that shoulder (unlike the road going clutch screws which are set to the depth you want to screw them into).

These screws, just like the original screws, require a special square headed spanner to screw them in - but we can also supply a good quality screwdriver type tool (Item 0882), which is perfect for this task and fits the square head just right.  One of the accompanyning photographs shows an original Norton square head clutch bolt with ours alongside for comparison, along with the blank stainless bar stock they are machined from.

Manufacturing notes - Broaching:  As with many of our parts and fasterners - we CNC machine these screws in hard wearing and non rusting stainless steel. However, to achieve the distinctive square head of the original pattern requires specialist (and expensive) rotary broaching equipment and multiple CNC operations to achieve.  But unlike the original Norton bolts I have seen (which were made from a much softer steel, then nickel plated - and often have their square heads 'rounded'), these screws are made from stainless steel - which unfortunately is a difficult material to broach, due to its hardness.  We actually have to - pre-broach them with a fractionally smaller square in a hydraulic press, then they go to a vertical pillar drill to be final broached - before then going back onto the CNC machine - for final head machining (because when broaching, a broach square requires a countersink for centralising, which is then removed), and at the same time the broacking 'scurf' is removed from the centre of the hole.  Therefore, for such a simple (and relatively shallow square) on the final screw, there is actually multiple operations 

Therefore we appreciate this is not the cheapest of screws - but it reflects the setup cost and manufacturing time to make these in small batchs (I only make them because there is a demand and they were originally fitted on Manx Nortons - frankly, I do not enjoy making them at all!).

Finally, we also sell the correct original Manx Norton type square section clutch springs (Item 0387) and billet manufactured Manx type short spring cups (Item 0610) to match these bolts.  


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