The Blog Oldracers posts - Grey Flash Diary Mar 2012

Grey Flash Diary Mar 2012

vincent grey flash surtees 1951

You may remember those shiny metal puzzles, the bent nails or the entangled rings, Perhaps the fiddle of getting the assembled gear cluster into a twin gearbox seems complex, well those tasks are small fry compared to fitting the gear selector ‘stirrup’ into the racing Albion gearbox. First of all I could not do it, then I thought maybe the ‘stirrup’ was from another box, then something interesting came up on Radio 4,and Bingo! Suddenly it was in the box, trouble was I had no idea how I did it! Then since I had a lot more to do in the box before final assembly, I had to get it out again. I struggled and struggled, my mind wandered and then…. It was out again! It took a lot of re-try’s until I discovered the trick was to put it in upside down and backwards, of course how silly of me, its 1940’s reverse logic, no wonder we cracked the Enigma code.
The ‘stirrup’ that selects the gear pivots (swings) on two 7/16 screws with pin ends that screw into the thin wall of the gearbox (Not the most enlightened design) and over the years, not surprisingly, the threads had almost gone. There are two short bosses to deepen the available thread, but the whole assembly is too short to be a good subject for helicoil, so I was encouraged by a good engineering friend to use ‘Time Sert’ thread reclaim inserts. These are a very ‘up country’ method of thread reclaim, with an internal thread as required, and an external special thread cut with a drill and special tap provided in the kit. They are also expensive, with a 5 insert kit around £40, and since it would appear that the thread for the standard inserts was a strange imperial (7/16 UNF or there about’s) my friend offered his metric 12mm equivalent, so I inserted the inserts and made up two new pins using two 12mm low socket screws.
Of course all this fiddling with the stirrup in an empty box may be twice as difficult with cogs in position, As it is, I notice that I have one mainshaft and two layshafts, and of course both layshafts are different. One is short and splined all the way at the gearchange end; while the other is longer and has a plain end (my guess is that the short one is the correct one). Also reading some Royal Enfield material (there is precious little other information on Albion boxes) there is, it would seem, a plethora of shims, spacers and spinners that fit in their boxes, while in my box of parts I have none all! So from the Enfield parts list for a 1950 Enfield twin (Heavyweight box) I picked all the shims and spacers that looked appropriate, added an 18T sprocket, crossed my fingers and bet on the conservatism of the Albion design team and placed an order with Hitchcocks Apart from internals of the box itself, it begins to dawn on me that the original installation of the assembly as fitted to the 30 odd Grey Flash factory builds, was (how can I say this delicately?) “A bit of a lash up”. There not a lot of clearance between adjacent components (some of which I have to make) and some of the original solutions are ideal. Trouble is with a job like this not only is it measure 3 times, cut once, but the conformation of the final drive alignment (which is what I am aiming for) is at the end of a long sequence of work. I have now collected my belt drive from Bob Newby and a fine piece of engineering it is too. Its use also dictates that I should keep primary drive area clean. So I have fitted a mainshaft oil seal as per Richardson. A final proof that I am becoming an anorak is that I actually had the requisite 3/16” Whitworth tap in my tool chest (Even to an Imperial devotee like me that is a bit of a way out thread, but engineering wise I believe it is correct).
Other little tasks included making a special longer 5/16 stud to replace the lower E109/5. (That is all that holds the front of the cranked link behind the chaincase!). And I also managed to slip a few items into a batch of Scott parts going to the plating shop for Electrolysed nickel plating. That finish is the only viable replacement for cadmium. However I know I shall have to get a big plating batch together just for the Flash at a later date.

  • Posted on May 8th 2012
  • By Tim
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