This listing is for a complete Stainless Steel Fork Spindle Kit to fit Douglas 2 3/4hp models, fitted with the earlier type front girder forks fitted between 1913-19 - of the type shown in the accompanying photographs.  These forks are easily identifiable by the four curved links connecting fork blades to top yoke.  However the very early models of these forks (1911-12'ish?) had straight links, but the . 

However, these spindles are not of the type fitted to the later forks that were introduced on some bikes from approximately 1917 through to the early 1920's - they are identifiable by having round fork tubes, unlike this earlier type which are oval.  These should not be confused with the next model of forks which were introduced approximately 1917, as these will not fit that later model.

A set of original Douglas 2 3/4hp fork spindles removed from an old and unmolested set of forks were used as the template for these spindles.  Likewise, the castellated nuts were copied from the original nuts that were fitted 

Kit Details:

• The kit consists of 4 fork spindles, 8 castellated nuts, 8 washers and 8 split pins, all in high quality stainless steel, the hex nuts being in the original imperial spanner size (now getting difficult to obtain in stainless steel) 
• The fork spindles are CNC manufactured from Stainless 316 (a higher grade/strength of stainless steel used for fork spindles on other, much heavier, girder fork models).  
• Oversize Fork Spindle Bearing Dimension details: The original Douglas fork spindle bearing faces had a diameter of 7/16” (equivalent to 11.1mm).  Because original forks will now be at least 100 years old and be showing some signs of wear – and because the original fork blades/top yoke castings do not look to have enough metal in them to safely bore out and fit bronze bearings, we have manufactured these fork spindles to fit a 11.5mm spindle hole bore.  In the case of the original refurbished forks in the accompanying photos (which are the forks to fit my own Douglas 2 3/4hp model), the spindle bores have been bored out to 11.5mm with a new (i.e. sharp!) hand reamer and the spindles are a nice size fit.  This was quite simple to do – and I was able to carry it out carefully using a good quality electric hand drill on a slow speed with plenty of light oil/cutting fluid.  Sorry, but for the reasons given above, we do not manufacture spindles of the original 7/16” diameter – so if wish to retain the original bores – please do not order this spindle set, they will be an incorrect/tight fit.  Email us on sales@racingvincent.co.uk if you require more details
• Oversize Fork Side Link Spindle Diameter Details: Likewise, the shoulder of the spindles that fit through the original (curved) fork side links have been made slightly oversize, to fit a reamed 8.5mm hole.  The original link holes would have been 5/16”/7.93mm, so this equates again to approximately 12 Thou of an inch oversize.  As with the side links on the original forks in the accompanying photograph, we found the link holes to be slightly oval – and reaming them with an 8.5mm hand reamer was a simple task and helped ensure a better fit of the new spindles
• The castellated nuts replicate the original nut's dimensions - i.e. they are deeper than standard commercially available nuts, with 0.525" (1/4 Whit) spanner size.  The width and depth of the split link castellations are as per the original nuts - we also linish the nuts so they look nice! (see photo)
• Please Note:  The threads on both spindles and nuts are 5/16" x 26tpi BSC.  I cannot be sure, but I suspect original fork spindles may be the Douglas specific 25tpi thread size.  We have not tried to replicate that obsolete thread size as taps are no longer available - so both nuts and spindles are manufactured with 26tpi
• Each spindle is crossdrilled on the thread end of each end (with a 2mm endmill) to take a split pin, in the same location as the original spindles
• Other Design Features:  We have tried hard to replicate the original Douglas fork spindles shown in the accompanying photographs.  As you can see on both short (top) and long (lower) original fork spindles there is slot milled along the length of both bearing faces – which is to allow grease to flow along the bearing length from the central grease nipple.  We have also replicated this feature on our spindles – and you will see each spindle has a similar slot milled along the length of the bearing area.  You will also notice there is an additional lip on just one side of each spindle.  This is an original feature of these forks, which we have replicated on our spindles.  I am not entirely sure what was intended to be fitted on this shoulder/lip, but the original Spare Parts Catalog of that era shows a 716D Spring Washer, so maybe that is what is needed (note we have not included a spring washer in the set, as not sure ourselves – please update us if you have an original bike and know!).  
• To finish off the kit, each set comes with 8 flat stainless washers, as well as 8 stainless steel split pins. They come with nuts/washers fitted (and threads greased), to ensure burrs from split pin milling removed)

As mentioned above, given the obvious wear original forks are lightly to have to their fork blades and side links, these spindles have been manufactured to a logical and beneficial slight oversize - therefore before ordering, please ensure you have read and understood the details above and are comfortable they will be suitable for your machine. 

If I get enough demand for standard dimension spindles I may consider writing a revised set of CNC programs for those - but due to the number of operations required to produce these sets (you will notice there is milling as well as lathe work to manufacture these spindles/nuts) - I hope you will appreciate I will only go that route if enough people require them

Update February 2021:  We have now sold out of this initial batch of fork spindle sets.  We will be making another batch in the future, but please email us at sales@racingvincent.co.uk if you wish to reserve a set, as we may prioritise that new batch if we know we have customers waiting for them.

This is the castellated nut as fitted to the front fork spindles on early Douglas models - approximately 1912-1919.  They are CNC manufactured by us, copying an original Douglas fork spindle nut as a template.

The nuts are deeper than commercially available nuts, and use the the correct imperial 0.525" accross flats hex, to fit a 1/4 Whit spanner, as per the originals.

Note that the thread on these nuts is 5/16 x 26tpi BSC (not Douglas 25tpi thread).  I am not entirely sure, but believe original early Douglas fork spindles may have used a Douglas specific 25tpi thread.  Although our nuts will start to go on an original fork spindle with a 25tpi thread, it is not good practice and I cannot advise doing it.  Therefore - if you are unsure, please try a commercially available nut 5/16 x 26tpi BSC nut on your spindle first (or use a thread gauge if you have one), as unfortunately we cannot accept returns on these nuts (as we cannot check the thread will have been stretched) - hope you understand.

Apologies these nuts are not cheap - but they are not easy to manufacture, each slot has to be individually machined which makes them very time consuming on our machine (and actually when I tried to speed this process up, ended up snapping the miniscule endmills!)

Each nut is linished and comes with a stainless steep split pin

This item is for the disctinctive round head 'captive notch' type engine bolts and 5/16 x 25tpi nut combination, as fitted to the top clamp of early type douglas 2 3/4hp girder forks (approx 1912-18). These bolts are CNC'd in stainless steel with correct threads and have a captive silver steel pin fitted in each bolt. 

the Item listing is for one bolt (with silver steel pin fitted), one nut and one washer - all in stainless steel.

Background Information:

As with the engine bolts we also manufacture (Item 0976) - these round headed bolts were of the type originally fitted to the early type of forks on Douglas models between (approximately 1912-1918), where the original bolts were cast/forged with a notch under the round head, which corresponded with a similar indent in the steering head - so the bolt could be tightened with just a single spanner on the nut. 

Note; I believe the later (post 1917?) type fork also used a similar 'notched' bolt - but was of a longer length (part number 1583d) - sorry but as I have the earlier fork type fitted to both my own Douglas's, I do not have an original 1583d bolt to check against - but expect that if you have the later type forks, this bolt will not fit (however, our engine bolt Item no 0976 might fit - email us on sales@racingvincent.co.uk for dimension confirmation).  Although you may see other photographs of my own Douglas showing it to be of 1919/20 vintage (its frame number is actually 1920) - it has been purposefully fitted with the earlier (pre 1918) forks, as I have built the bike as a 'TT Replica' and the original 1912-14 TT bikes were fitted with the earlier type forks.

We have replicated these original Douglas style bolts - CNC machining them in stainless steel with correct 5/16" x 25tpi Douglas threads, and then a small hole milled under the head to accept a 2.5mm silversteel pin, which is then located with Loctate Retainer fluid (industrial retainer for steel).

The inset picture in the first photograph shows me holding one of our newly manufactured bolt up against the girder fork steering head of the current bike I am restoring.  That steering head actually has an original Douglas bolt fitted, but you can see that the head design is the same on our bolts (and obviously does not have the corrosion and wear the original bolt has!)

Sorry these are not cheap - but as well as requiring custom made taps for the threads, the extra effort of milling and fitting silversteel pins make them very labour intensive to produce

There is no reason why - if you are not fussed, that you could replace this type of Douglas bolt with standard modern 5/16" hex head bolts and nuts (and instead use a spanner on both sides when tightening) - but if like me, you would prefer to replicate the original Douglas design and originality - then these do look very nice when fittted

This listing is for a pair of shouldered extension bolts to fit early (pre-1919) Douglas fork spindles, and allow for the fitment of an Andre Fork Damper, as per the type in this photo. 

These are designed to fit to the original 'early fork' type Douglas fork spindles as fitted to 2 3/4hp models from approximately 1912 - 1919, and provides a shouldered shaft that will allow for the fitting of a reproduction Andre (friction disk) fork damper, of the type often fitted to Douglas racing and speedway bikes in the early 1920's.  

The background to these is that as part of my re-building a 1919-20 Douglas 2 3/4hp (but fitted with the early type forks) I wanted to loosely base it on a Sports/Racing version of this model, similar to those used at Brooklands both pre World War One (including by the factory team) and in the early 1920's.  I know it might be considered artistic licence to fit an early 1920's style Andre damper to the earlier type of forks . . . but it is a mod that could have been made retrospectively in the day . . . and I think it an interesting and useful mod - as well as definitely being a point of conversation!

I have made these two extension bolts to be of the correct length to be used with the Douglas fork spindles we also list - Item 0735, and as that kit also includes the castellated nuts, no other parts are required - other than the Andre Damper and washers, which need to be purchased seperately!  These extension bolts are just tightened to the fork spindles as the castellated nuts would have been, the Andre Damper is then pushed on to the shafts, then the original castellated nuts are screwed onto the end of the extension bolts - which are drilled to accept the split pins to lock the castellated nuts.

Although I do not offer the Andre Damper myself, I can tell you it came from Graham Brown at Vintage and Classic Shock Absorbers: 

http://www.vintageandclassicshockabsorbers.co.uk/

contact Graham at: grahamvcsa@hotmail.co.uk

The model you see fitted to my bike is described as - 'Hartford Motorbike Shock Absorber, 2&1 bladed, cast steel riveted on end eye, rubber end eye bush fitted'.

I can tell you that when the item arrived I was really impressed with its quality and think it really looks the business!, as well as feeling like it will genuinly help the damping abilitites of these forks.

As you can see in the last photograph - which I believe is of a young Bert Denly taken on a racing Douglas at Brooklands in 1923 - dampers of this type are not out of place on a flat tank Douglas with sporting pretensions! 

Note: email for further details on sales@racingvincent.co.uk if you have a later model Douglas and want to use these bolts - I can provide more details of dimensions

This item is for the disctinctive round head 'captive notch' type engine bolts and 5/16 x 25tpi nut combination, as fitted to early douglas models - i.e. 2 3/4hp (they may also fit 4hp models - but please email for dimensions).  These bolts are CNC'd in stainless steel with correct threads and have a captive silver steel pin fitted in each bolt. 

the Item listing is for one bolt (with silver steel pin fitted), one nut and one washer - all in stainless steel.

Background Information:

Original Douglas 2 3/4hp models secured the engine to the frame with two half clamps (part number 662d, shown in the first photograph) which matched up to the bottom of the crankcase which had similar half clamp lugs machined into them.  And then (like so many other Douglas fasteners of this period!), Douglas used their own special engine bolts with a round curved head and 25 tpi thread to fasten the clamp/engine.  In the first photograph in this listing - you can seen an original Douglas bolt (i.e. 100 years old), which although re-nickel plated, you can see an amount of underlying pittng and slightly worn thread.  

however, if you look closely at the original bolt - you will see that it had been cast/forged with a 'notch' under the round head - which matched up with a corresponding notch cast into the frame clamp (662d), which meant the head could be round (not hex) and there was no need for a spanner on the head of the bolt when tightening the engine bolts.

Not suprisingly - these bolts are now very rare, and I would imagine most are now either corroded badly, or the notch/thread are very worn.  I would also think it is reasonably common for later owners to fit (non-Douglas) later BSC 26tpi nuts in error.  Although I have a few of these original bolts - as per the re-nickelled one in the photo, I decided to make a batch - as a couple of the ones I needed for my own project bike were missing, or threads not great.

The bolts shown here have been CNC manufactured in stainless steel by ourselves and replicate the gentle curved head and diameter of the originals - so they look spot on.  Each bolt head is polished, so they look pretty too.  However, we then use a milling attachment on our CNC to side-bore the shaft of each bolt directly  under the head - to accept a 2.5mm Silversteel pin.  The silversteel pin is a size fit and inserted with Loctite Retaining compound (i.e. industrial steel glue), which holds it captive.  The hole is only bored for approx half of the shaft diameter, and being only 2.5mm should not affect the strength of the bolt.  As can be seen in the accompanying photographs of our new bolts inserted into an original Douglas engine clamp, the pins match up with the notch in the clamps exactly and work very well. 

Similarly, the nuts are CNC machined in stainless steel, and are of a slightly greater depth than commercial 5/16^ nuts (i.e. giving greater strength), and are also of the correct 5/16" x 25tpi Douglas thread form.

This item listing is for one engine bolt/one nut/one washer - all in stainless steel.

Note: Earlier models of Douglas 2 3/4hp models (1913 - 1919 I believe) also had an additional clamp/lug (part number 615d) to hold the brake pedal - which also employed these bolts.  The last photograph shows a modified version of this 615d assembly, which I have fitted to my own 1919/20 project bike.

Sorry these are not cheap - but as well as requiring custom made taps for the threads, the extra effort of milling and fitting silversteel pins make them very labour intensive to produce

There is no reason why - if you are not fussed, that you could replace this type of Douglas bolt with standard modern 5/16" hex head bolts and nuts (and instead use a spanner on both sides when tightening) - but if like me, you would prefer to replicate the original Douglas design and originality - then these do look very nice when fittted

This item listing is for a set of 4 cylinder barrel base nuts to fit the Douglas 2 3/4 hp models in stainless steel with washers.  These nuts are 5/16" x 25 tpi Douglas thread and have more depth than standard.  CNC manufactured in stainless steel.

As can be seen from the last photo, an original Douglas 2 3/4hp barrel nut was used as the pattern to manufacture these nuts, and we have had custom taps made with the correct thread.  These nuts are CNC manufactured by us in stainless steel and are the correct depth as originals (to fit on the special floating crankcase studs fitted to this engine type).  We also linish the flats of our stainless bar before machining, so the nuts look pretty as well.

Sorry these are more expensive than normal nut sets, but the cost of Douglas 25 tpi taps means we have to take great care in the CNC setup, to ensure we dont break one!  We also perform a post-CNC op to chase the thread again, ensuring their is no thread burrs after the parting off/countersinking.

This item listing is for Douglas 2 3/4hp Valve Caps, CNC manufactured from stainless steel - in 3 styles - the non spark plug/hollow type, 18mm spark plug type and 14mm spark plug.  This is a multiple item listing and it also offers Copper/Abestos type crushable valve cap washers to fit these Douglas valve caps.

These valve caps have been CNC machined by us from stainless steel billets, using original 100 year old (and very rusty!) Douglas 2 3/4hp valve caps as the pattern.  If we say so ourselves - they look very pretty and will definitely transform the look of your early Douglas twin, particularly if you are currently using corroded or rusty original items.

We took some time making jigs and writing programs to get these items correct - and as per the originals, the hex is milled to the original 'Imperial' size hex spanner size.  Being CNC manufactured, the machined finish is very good - but they are then lightly polished on a rotary polishing mop with stainless soap, which helps give them the look of original nickel-plated items.

We can also supply the original style copper/asbestos type crushable washers (although, in these modern times - the heat resistant material inside is no longer asbestos).  These rings can be supplied individually, or in packs of 6 - as they should be replaced each time the cap is removed.

There are 3 types of Douglas 2 3/4hp valve caps available as well as the crushable washers, as follows:

- 0897_1: 'Plain/Hollow' type Valve Cap - these are fitted to the lower valve of each cylinder, two required per engine.  The accompanying photographs show two original Douglas valve caps alongside ours, for comparison

- 0897_2: 18mm Long Reach Spark Plug Type:  I am not sure if 18mm plugs and 14mm plugs were fitted to Douglas and 2 3/4hp models concurrently (as this model was manufactured for a long period from 1910 to the mid 1920's but I have original valve cap examples of both sizes - but 18mm plugs are often associated with Veteran motorcycles, and I have decided to fit this size of spark plug valve cap to my own 1919 TT Rep, which was used for the photographs in this listing. 

Again, an original valve cap was used as a template. 

Note: if you are going to fit 18mm plugs, you will need to find the original type 'Long Reach’ 0.750” length thread plugs – which are now quite rare (0.5” is the more common length).  We can also supply modern reproduced KLG ML50 18mm plugs which have this 0750” length – see Item listing 0896.

As a final point on the length of spark plug threads – If you look at the original Douglas 2 3/4hp workshop manual, there is a cutaway view of the entire engine – which includes a cutaway of a valve cap.  This does show that the original spark plug was slightly recessed into the valve cap – but I am sure that fitting a more readily available 0.5” length 18mm plug would make the spark too recessed, and possibly affect valve timing and combustion.

These ‘spark plug’ type caps were fitted on the top of each barrel, two required per engine

- 0897_3: 14mm Long Reach Spark Plug Type:  Almost identical to the 18mm type, accept this valve cap will accept readily available 14mm 0.750” thread length spark plugs.  Again, an original valve cap was used as a template.  Using this type of valve cap will allow you to use most type of modern 14mm long reach plugs . . . as well as many readily available ‘New Old Stock’ vintage spark plugs that come up on ebay.  We can also offer a variety of spark plug accessories (Item 0895) that will make your modern spark plug look more veteran!

- 0897_4: Copper/Asbestos style Crushable Valve Cap Washer: Good quality ‘crushable’ copper/asbestos type washer for sealing valve cap.  Modern filling, but of type fitted originally and looks good when fitted with this valve cap.  This item is for single washer

- 0895_5: Valve Cap Crushable Washer – pack of six:  As above, but more economical as pack of 6.

- 0895_6: EW Valve Cap Query:  I am not an expert on the Douglas models that followed the (first) 2 ¾ hp 350cc models, but am aware the 350cc sidevalve EW model that immediately followed this model in the mid 1920’s had a valve cap that visually looks similar to the type we have made.  When I tried to fit an original 2 3/4hp cap to a EW cylinder head I have, I found that actually the valve cap holes on the EW head are fractionally closer together than the 2 3/4hp models!!

I have no idea why Douglas did this, but it does mean that our valve caps (as manufactured) do not fit in the EW head without a slight skim to the outer diameter. 

If you wish to upgrade your EW model to these stainless valve caps, then email us on sales@racingvincent.co.uk and I will consider if we can do this.   If enough interest from EW owners, I will also consider a new batch in the future with the fractionally reduced outer diameter

This item is the distinctive 0.600" Across Flats hex tappet guide that screws into the crankcase of all Douglas 2 3/4hp models (1912-1924). 

An original tappet guide from a (circa 1917) engine was used as a template for replicating these guides - we CNC machine them from stainless steel to the original dimensions - so should be a direct replacement into your engine if yours are worn or missing.

These are CNC manufactured to the original dimensions in stainless steel.  Price is each 

Note the bore of these adjusters is 0.250" (as per the original), and we bore and ream this final dimension.  While manufacturing these, I used a couple of examples as patterns (see accompanying photo of original spare engine - our new adjusters are on the left and the one on the left fitted, the original tappet guide is on the right) and noticed they did have some slight wear to the bore.  Not sure how much difference the wear makes - but imagine they might leak more oil when worn. 

As a final point - these tappet adjusters are screwed into the crankcase from outside - therefore if you are considering fitting new ones to an existing engine - it should be possible to just loosen the barrels enough to allow removal of tappets/adjusters, then unscrew the old tappet guides and screw in new ones, without the need to strip the timing case

This listing is for a set of 4 valve springs to fit all Douglas 2 3/4hp (350cc) models.  Springs are high quality UK manufactured to original pattern and design.

There are 4 springs per pack - enough for two cylinders/one engine.  Shown in the photograph is my own Douglas 2 3/4hp of 1919/20 manufacture.  They are manufactured by my main UK spring maker who has been making valve springs for a variety of classic motorcycles for many years

Note: we also manufacture the valve collars shown in the photos, see items 0729 and 0730

This is the valve retaining collar of the type fitted to Douglas 2 3/4hp models, used to retain the valve springs by means of this collar and a steel pin that fitted through a hole at the end of the valve. 

The typ shown here has a slightly modified design over the original - having an additional milled slot, to help retain the pin and prevent collar spinning around the valve. The collar is CNC manufactured from EN24T while the pin is from Silver Steel. 

Note:  I am told that the original design specification for these collars for the Douglas 2 3/4hp was to have just the recess - without the milled slot (we also manufacture that type - Item 0730).

However, when I originally manufactured these collars, I took the design from an original collar which had a similar slot recess.  I cannot be sure if this was just wear to an original type collar, or if someone had modified that collar - but from an engineering perspective I feel the additional slot is a better solution as it should ensure the pin is more captive and more importantly stops the collar from spinning around the valve - I have a couple of examples of old valves where there is clearly a wear groove on the top of the valve where this has happened.  I am not an expert on this engine in use, hence I offer both types (however, I am building my own project bike with the modified design, and will report back once the engine is running)

This listing is for the original type - consisting of one collar and one silver steel pin (4 required per engine)