The Blog Oldracers posts - Grey Flash Diary Apr 2012

Grey Flash Diary Apr 2012

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Re-reading my diary entry for last month I felt a little uncomfortable about my comment on the arrangement of the fitment of an Albion box on a Grey Flash, where I called it a “bit of a lash up”. Its pretty clear that although the announcement of the Flash before the 1949 show quoted optional Burman or Albion Boxes, Burman failed to come up with the goods and arrangement of frame ties and links for the Albion box was then developed and used. Certainly now I have done the small amount of machining required to the back of the chain case boss and its all been bolted up together, it is a ridged and secure solution to the marriage of two previously unrelated components.
However in the “Tales of the snarling beast” there is an account of a “lash up” which occurred the following year, It’s the 1950 TT and there was PCV and his Grey Flash team in the Isle Of Man, in digs, far from the ‘comforts’ of the factory, working in a lock up garage, the country still in post war austerity, and the company in receivership. The pre-war BAR Burman gearboxes that had been fitted to the Flashes on the orders of PVC were a failure, and the new gearboxes that Albion had supplied, somehow needed to be fitted. And practice time was draining away. In John Griffith’s book “Famous Racing Motorcycles” there is a contemporary picture probably taken at Stevenage before packing for the IOM of one of the TT Grey Flash’s and what is shown is a long way from an Albion configuration, so as PCV relates ‘long all night working ensued’, Lash up? Perhaps, but “heroic lash up”, would in this case, be a more appropriate description.
Bob Newby was correct in his estimate of 208 mm for the centres of the belt drive. With the belt tensioned to the 90 degree twist test, the main shaft is almost spot in the middle of the chain case hole. The belt protrudes out the chain case by about ¼” with a potential of perhaps 5/8“ from the chain case face, so the wall cast across the inside of the cover to reduce the oil rain falling on the Burman clutch (or to keep it in) needed to be relived in two places to clear the belt and its flutter arc. Externally however the chain case will look standard and the belt drive will be a lot more effective and smoother than a chain, Its certainly a technology that has come on in the last decade or so thanks to pioneers like Ian Alexander who I think was using one in the IOM TT back in the eighties.
Incidentally I have built the engine and gearbox on a stand which looks like two letter H’s on their side but with the top rear legs missing and the top front legs bolted through by two dummy longer bottom crankcase bolts, As this stand itself is bolted to my hydraulic lifting platform this allows me to build up (and later take apart) the bike at an easy working height, with plenty of clearance twixt crankcase and bench.
As all the studs into the crankcase timing side were missing I thought I had better pop new ones in and assemble the timing gears main idler and cam, a job made simpler because I always leave out the breather pinion on a race engine and of course the dynamo pinion. I fitted an Mk2 cam and I shall time it later with the “six-degree rule” method I have used with all my Vincent builds in recent years, (I have no reliable timing marks anyway). Lubricating the assembly as I fitted it, cemented my decision to use ‘R’ as my lubricant of choice, I have used it on the racing Comet and the alphabet twin road bike for many a long year so it was a no contest really.

  • Posted on June 10th 2012
  • By Tim
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