This item listing is to provide a replacement sprocket for your original worn Douglas ‘5 hole’ 1/2" x 3/16" early type gearbox sprocket – using a modern industrial equivalent sprocket template, machined to your desired internal diameter. This 5 hole type sprocket was of the type commonly fitted to pre 1920 Douglas 2 3/4hp models - not the later 6 hole type, which were of a different pitch.
This bespoke service makes the assumption you will re-use your original Douglas sprocket, having first removed the old teeth yourself – and machined a good centralised outer diameter – providing us with the outer diameter of that machined boss, so we can machine a ‘blank’ industrial sprocket to the same dimension – with a slight groove on one side to hold braze.
You can then ‘tap fit’ this new sprocket onto your original Douglas 5 hole centre section, and braze the new sprocket in place – as I did in the photographs shown here.
Note – the price shown is indicative only (we order the sprockets in as special order – so will quote a machining price once order placed – no obligation to purchase until the sprocket order is placed). Also note – these industrial sprockets are hard, but not hardened – so may not be as long lasting as original sprockets - however as original sprockets have been unobtainable for many years – and few people run these models for high mileages – This sprocket should provide a suitable compromise.
It is expected the owner takes full responsibility for supplying the correct internal diameter the new sprocket is to be machined to – and undertakes the task of removing the old teeth and brazing the new sprocket to the original boss themselves. Email for further details.
Note – the original Douglas sprocket shown in the photograph was 30 teeth, however, the new sprocket supplied will be 31T (or possibly larger if you require it) to allow for the brazing process not leaving braze overly close to the chain.
We can also supply good quality Renolds chain of the correct pitch/length – see item 0867
Full Fitting Service Option:
Dependent on my availability and condition of your original sprocket – I may be able to undertake this work (at customers own risk) of fully machining your original sprocket and fitting a new one – but cost would be substantially higher than shown, due to the complexity of the job – expect a total cost to remove old teeth, machine boss, machine sprocket to fit, braze new sprocket on of somewhere between - £180 - £200. Please state if you require this service and we will email you back for more detail.
We would much prefer you carry out the work yourself though – and can provide you detail information on how to do this if reqired – following same process we followed