A Special Builder's Notes


The Special Builder's Breakfast Club

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09 January 2018

More Rush 'n' Tear.

I got back the other day to find Learned Counsel and The Racing Driver manoeuvring the MX-5 engine into the Locost chassis.

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It appeared to be quite tight and at one point it looked as though one of the cooling castings was going to arrive bang opposite a frame member - it couldn't have been placed more perfectly. Fortunately, the casting in question can probably be made redundant; that's lucky. The remote control extension from the gearbox was also a bit of a squeeze to get into the tunnel but some judicious cutting here and there, sorted that out.

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The Coffee Run to Leon and Awkward's workshop found both of them contemplating the A7 Special's diff and drive shafts. With the wheels up in the air and turning them by hand, there was a slight grinding heard coming from the diff and, as is their custom, in less than an hour everything was out and ready for inspection. All seemed to be fine and there was no positive ID on the problem before I left to make a start on taking apart the Cushman Husky engine.

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With the fuel tank out of the way, I could get the gearbox and clutch cover off.  The clutch is an enclosed multiplate system located behind the smaller twin gear wheel. The horizontal bar is the clutch actuating fork - that disengages the twin wheel from the drive and the large wheel (also a twin gear - there's another smaller gear behind which isn't visible) is moved in and out by the lever sticking out of the case at top left. I didn't go any further as Awkward was coming by the next day to give me a hand and to see if we could get the engine running.

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There are two speeds and a neutral - confirmed by the indents on the splined shaft which accept the spring-loaded ball bearings; that'll be fun reassembling those! The problem was that nothing seemed to work properly. Only one of the gears could be engaged and the clutch didn't seem to want to compress as much as you might expect. As soon as the bigger gear came off, all was revealed. There was a piece of aluminium floating about - the shiny bit in the tray - and a ball bearing in the bottom of the casing. Removing the clutch shaft was a bit of a Chinese puzzle - both arms were keyed so the shaft had to be knocked outwards to get the first key out and then back in to get at the second.

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Removing the clutch showed that disc alignment was the problem. Three of the discs were able to run on the splines but the other three had got their tabs out of line and prevented full disengagement. So, with all that stuff out of the way, it was time to see if it still had The Vital Spark!

As you can see, it did. I apologise for not being able to rotate the video but thanks to the clever people at Microsoft who no longer support Media Player, I don't know how to do it. However, what we didn't know about the Husky, (though by the state of the crankshaft taper, we should have known) was that someone had been at it in the distant past and we didn't notice a crack in the flywheel.

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That's going to slow us up.

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