Douglas 2 3/4hp - Early Square Brake Lock Ring Bolt - 25tpi Douglas Thread (Stainless Steel)


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Douglas 2 3/4hp - Early Square Brake Lock Ring Bolt - 25tpi Douglas Thread (Stainless Steel)

Product no.: 0689 DG234_003

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£5.50
Recommended Retail Price, plus delivery


This is a shouldered bolt of 0.710" shaft length, with the distinctive shouldered square head, of the type used on brake assemblies of early Douglas 2 3/4hp models.  It is intended to feed through the circular locking ring used on early Douglas 2 3/4hp brake pedal assemblies, which is used to adjust the position of the brake pedal on its shaft. This bolt has a  Douglas 0.257" x 25tpi thread, as per the original bolt used as a pattern.  Please measure your original brake pedal lock ring thread/bolt to ensure you know the correct thread before ordering.  It is CNC manufactured in stainless steel

I have made a small batch of these bolts as part of the restoration of my own Douglas 2 3/4 hp model, of which I am building as a 'loose' copy of a sports/racing version of this model - a Works model of which Douglas won the Isle of Man Junior TT with in 1912.

I copied this bolt from an original item which was part of a very rusty but original early Douglas front brake assembly - which I am almost certain was of the type of assembly fitted to the 1910-1912 models, to the front downtube.  I have seen a very similar assembly and brake pedal fitted to period photos of this model - where it was not uncommon to have a two sets of footrests, the normal set just in front of the two speed countershaft, and another forward positioned assembly mounted at the base of the front down tube.  

When purchased this front assembly was very rusty and dilapidated - but looked original and unmolested.  The assembly included the brake pedal (see accompanying photos), original Douglas brake positioning lock ring and square headed bolt for that locking - which is the item copied here - CNC machined with a shouldered/milled square head in stainless steel

Although the square headed bolt was very dilapidated, I was able to de-rust it and used it as a template for CNC machining a copy in stainless steel, including lipped square head, which has been milled from round bar. 

This particular bolt is of a very unusual dimension - 0.257" diameter x 25tpi (threads per inch), but I measured it carefully from the original bolt (the original Douglas bolt - shown in one of the accompanying photos next to the CNC manufactured version), and once manufactured, fitted it to the original lock ring - where the thread fitted perfectly.  I myself am surprised the thread diameter is slightly oversize from the more traditional 0.250" diameter - but I did make a sample one at 0.250" as a comparision - and the 0.257" is definitely a better fit into the lockring - so I believe it to be correct.

If I say so myself this bolt is very pretty, when polished looks almost indistinguishable from the original nickel plating of this era and will not rust!  And probably the first 25tpi bolts made for many years!

Note:  see also item 0690:  Just in case you think your own locking ring is the more standard BSC 26 tpi thread - I have also made a small batch of these bolts, but with a 26tpi thread.  

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