Black Dog Classic Motorcycles

MY BROUGH SAGA

Part Four

Now to the good bit, assembly, I spread the newly painted and chromed bits out on a clean sheet in the garage. Rear stand and return spring were fitted first, followed by the forks, mudguards and stays, then the wheels. I had had the wheels powder coated in one piece (rim spokes and hub), but before sending them for coating, slackening each nipple one turn. On return new nipples being fitted. The effect of this looks really good, once trued up in the frame and forks.

Engine, gearbox and clutch fitted, oil tank and headlight attached, all going well until I came to the previously mentioned primary chain cases. They would not fit without catching the clutch on their insides. As I said previously, when I did the dry build it was without the clutch being mounted on its shaft. A bit of head scratching later, I realised the problem was not the clutch, but the cases! This after I had painted and sanded to a fine finish! I had also fitted the rear chain guards around the ends of these wrong cases! A late night phone call to John English was to solve half the problem. He sent me what bits he had, which were odd halves and I found I had the correct top halves, but a damaged bottom halve, this with a shallow clutch dome. I built this up with plasticine, to a match with the correct clutch dome. I am fortunate to live near a small non-ferrous foundry, I took the two halves down to the owner who looked at my efforts and frowned, shook his head, ‘should be ready in a week’, he pronounced, ‘but expect a bit of shrinkage as the casting cools’, Something I had not thought about. A week later I picked up a nice smooth shiny job. Little did I realise the work that lay ahead in removing the excess aluminium from the inside of the clutch dome. Anything from a quarter to three eighths of an inch would have to be removed, and the only way was by hand

I started by filing the mating face so as to fit the original top supplied by John, next I bedded them down on a surface plate and marked the holes in the top half, then drilled and tapped quarter B.S.W. in my new casting. Bolted them together and shaped the outside using a bastard file and flap wheel, until the contour fitted the top, now only shrinkage showed at the ends of the case, here I built up with weld and filed back. Finish with a fine flap wheel and externally these cases looked well. Now for the hard bit, how to remove the metal inside the dome!

I started by fitting an end mill cutter into my pillar drill and with the bottom half of the primary case clamped into a machine vice I set a cut depth of one eighth of an inch and tried moving the heavy machine vice by hand. This worked much better than I had anticipated, with little or no judder, due to the weight of the vice. I worked my way down in small steps, until I reached a point about 3m/m from breaking out. I then started at the top cutting between the steps, leaving the roughness to be removed with a rotary file fitted in a hand drill, a tedious job, but well worth it.

I then did what I ought to have done before, checked the clearance of the cases with the clutch fitted! All was well. I could now get them powder coated and two pack enamelled. I now had to weld a piece into the front of the top chain guard, so as to make it fit my slightly smaller cases, then re-coat the guard! I was now back on track with the build, next stage being the electrics. The three-brush dynamo needed reconditioning, I was without a light switch with a half charge position or a half charge resistor coil but I had a short two-brush dynamo on stock, I therefore decided to change to a voltage control system. The seat down tube not having been drilled for Lucas voltage control unit, I decided to fit one into a toolbox, the wiring loom being no problem, as I make my own. I get a lot of satisfaction from wiring and playing with old charging systems, the only awkward bit being the rotary handlebar switches, the insides of the bars getting a bit congested with all the Bowden cables for the twist grips and the inverted levers.

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