Author Topic: Douglas 2 3/4hp - Early 2 Speed Gearbox Sprocket - Enquiry Only?  (Read 515 times)

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Offline pvn06

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Hi Everyone, Merry Xmas to You All,

Before anyone gets their hopes up . . . sorry, but despite the heading - this is not a listing to say I have had sprockets made, but rather an enquiry to find out if anyone knows of anyone that has already had made early Douglas 2 3/4hp gearbox 5 hole sprockets (as numbered Number 1 in the accompanying photo), or failing that . . . a gentle enquiry to find out if there are other Douglas 2 3/4hp owners out there who are also in need of a sprocket - because their own is either worn out or missing?

I am not going to fib - I think at this stage it is unlikely I will have a batch made - I have already made some enquiries and it looks neither easy or cheap, but I am talking to a specialist sprocket manufacturer at the moment, and although they are not able to make the entire sprocket (they do not have ability to make the taper) - they have said they can make a 'blank' sprocket with the right tooth profile, that I could machine to size and braze to my original worn sprocket.

Even this option is expensive - but I thought before going ahead and biting the bullet on just a single sprocket for myself . . . I would test the interest of other similar owners here, either to see if I have missed something - and there are already some available, or if enough interest . . . to consider a larger batch.
The photograph of the two sprockets below are I believe the early (pre 1919) type - which in most photographs are shown with 5 holes.  Next to it is a later 6 hole type which I believe was fitted to a number of later models into the early 1920's.  At this stage I am looking at the early type - which I believe is 1/2" x 3/16".   I believe the later 6 hole sprocket is 5/8" x 1/4"- I have no plans to have any made this size in the near future - but let me know if you need one, it will at least let me know demand.

My email is paul.norman@racingvincent.co.uk and I am probably going to go ahead with a single sprocket for my own bike in the next 3 weeks, so this is just a quick check with other owners before doing so - please be quick if you do have an interest, once I am committed to a single sprocket I doubt I will take things any further.

And finally - a quick photo of my own Douglas 2 3/4hp build (@1919-20 TT Rep, but with earlier front end fitted).  It is now back on its own wheels and engine and 2 speed gearbox now fitted.  As you can see the gearbox is in need of a good sprocket!!

I will cover it in a separate posting, but if you look carefully you will see that - although I have fitted the earlier type forks (as fitted to the 1912-14 TT bikes), as the chassis/engine are 1919/20 - I have fitted an Andre damper to the forks, of the type sometimes fitted to Brooklands bikes (including Brooklands Douggies) in the early 1920's - I could not resist the chance to add a bit of BS!
Anyway - as I have already made the earlier type fork spindle sets for sale (see our RacingNorton website Douglas section), I also made a few extra sets of the stainless steel extension bolts to mount this type of Andre dampers to that fork type.  I will be listing them in next couple of weeks and will provide more details (including where I was able to obtain the Andre damper) in a separate topic here when I do so.

Best Wishes and Happy New Year to you all!
Paul
www.RacingNorton.co.uk and www.RacingVincent.co.uk



 

Offline pvn06

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Hi All,
Just giving an update to this thread.  Unfortunately the custom sprocket maker was not able to supply full sprockets - and a custom blank was just too expensive and still needed additional work from myself.

I did find a supplier of industrial sprockets of the right pitch though . . . here is progress so far, see photos.
Just need to braze now.
A lot of work, and not sure I want to make more - but may consider making a batch of 'blanks' to go on existing sprockets as per the method here.  Email at normal email if interested

Best wishes
Paul
www.RacingNorton.co.uk

Offline GlenDouglas

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Hi Paul, something I have see not investigated yet, get the sprocket machinined and then the teeth laser hardened.

There are copies out there that will laser harden, heat treat. Something on my list to do as have same issue.

Regards Glen

Offline pvn06

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Hi Glen, thx for this.

Actually I was thinking originally of trying something similar - but have decided for the moment (being busy on other stuff and the current COVID position) - it is probably worth just trying this sprocket out on the road first, and seeing how heavy the wear is.  After all, the sprockets I am using are intended for industrial machines (I assume food conveyors and similar) . . . and assume they must be something reasonably hard wearing - and in reality, will an engine as mildly tuned as a 2 3/4hp really put that much wear on the sprocket? - especially given the lowish mileage most of us do on the bikes.

That said, thx for this Glen and will let you know how it progresses.  And BTW - I wish all Douglas owners and readers of this article all our best wishes to you and your families.  Although it is difficult for everyone at the moment - I hope some of you are getting chance to work on your 2 wheeled workshop projects!
We are still operating - albeit from home, and I am still making Douglas parts imbetween Norton parts when I get chance.  A few weeks ago I finished a batch of Stainless tank retaining bolts (weirdo Douggie thread size) and will shortly be making a batch of stainless valve caps (both plain and 14mm/18mm spark plug type).  Will also be offering Renolds chain kits for this type of sprocket in next few weeks . . . the chain was on order when the lockdown hit a couple of weeks ago.
Best wishes
Paul
www.RacingNorton.co.uk and www.RacingVincent.co.uk