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.
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