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SW Douglas - Doug Kephart

 

SW Douglas motorcycle advert

SW Douglas motorcycle

Not many original SW models left the factory. While the DT was favored for the cinder tracks, by 1928 folks were looking to other marques for road racing iron.

This particular example was rebuilt circa 1953. The major deviations from originality are the drop center rims (original clincher) and home made chain guards (originally none). Having said that, the rest is not too far off what an SW ought to be.

(click on pictures to see a larger view)


Mine seems to have started out as an SW - the DT frame has only one factory installed footrest lug and no anchorage for a front brake - but is otherwise the same.

Many DT machines have been successfully converted into SW specification since by welding on appropriate lugs and fitting a clutch and mudguards.

While there are a limited number of events for using your restored DT, any VMCC potter through the countryside (at 70mph!) is suitable for an SW.

SW Douglas motorcycle - closeup
SW Douglas motorcycle


The close ratio gears fitted to my machine are in fact DT competition ratios. I do not think anyone knows for sure what ratios were fitted to an SW, but it was probably what ever was available in the other road ratio gearbox fitted to the OB/OC models at that time - commonly known as 'vintage wide'. Because so many DT machines were made, those ratios are the most easy to find.


All the Douglas 'cross-over' 3 speed gearboxes fitted to the OB, OC, RA, DT, SW, F/G, and like models has a 'crash' second gear that shifted in and out of mesh with the gear teeth rather than dog clutches. So the 'box had a pretty hard time of it - except the DT, which you did not actually shift during a race.

The DT ultra close ratios were more for selecting between 1/8, 1/4, and 1/2 mile tracks I am told. Between that and a selection of sprockets, all bases were covered. Preference was to use top, or direct, to minimize power losses. If you could afford a good selection of sprockets to cover all your events, you could remove all the gears and fit a solid countershaft and save a bit of weight.

I have encountered two basic DT sets. Close, and the ultra-close as fitted to mine. The ultra-close ratios are so close, it makes the machine impractical to use on the road.

Currently it is geared with the sprockets for a good turn of speed in top. This makes first gear start at about 15mph with perhaps the clutch fully home at 25mph, if the engine does not stall.

Changing the sprocket for a more get away in first would see the engine screaming its lungs out by 45mph. Hence a wider spread of gears is required. If you can find a set of road ratios these days, more than likely they are well used up. I am having a new set of gears made and should have the new gear blanks machined and ready to deliver to the gear hobbing firm next week. I look forward to riding with the new ratios in one of the events on our Spring calendar.


SW Douglas motorcycle - closeup
 

 


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