A Special Builder's Notes


The Special Builder's Breakfast Club

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06 November 2012

Pole Position....

..... so to speak. There I was congratulating myself on the new gear linkage being a success when, after further experiments, it wasn't performing quite as I'd hoped. The first problem was the angle of the gear lever in its various positions. The selection of 1st and 2nd gear would be likely to earn me a thick ear from Miss X; 3rd and 4th were fine and reverse would have been, well, incommodious. Clearly some adjustment to the travel was required so a complete re-jig was in order and, having re-jigged, the next problem was that although 1st and 2nd were now out of the no-fly zone, the effort required to move the selector was unacceptable. The bellcranks needed to be remade and the rods adjusted accordingly.

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After a couple of evenings cutting and filing, the lever travel is almost right - there's still scope for a bit more adjustment - and the effort required to select and shift is how I'd like it; just enough to be positive but not so light as to be a bit hit and miss. I'm going to have to extend the selector casting somehow - at the moment I'm using a bolt and spacer to push the rod out parallel with the box - because the rods need to be a straight run for max efficiency. A rose joint would work but it's not right.

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Looking at this picture reminds me that the other morning in the small hours, I was going through the design and remembered that the brake adjusting rod falls more or less where all these rods and levers are. I just hoped that it was all going to fit in. I popped up to the workshop before work and took a picture of the box with the brake rod to overlay onto a picture of the gearbox as it now is...

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.... that was a close run thing!

Now I just need to draw up the saddle for the laser-cutting people and that's the gearbox put to bed. I can have a bit of fun with the design of the saddle though I must make provision for the attachment of a gate. The nature of the box and its mechanism demands a gate for positive location of the gear lever. It would have been nice not to have needed one but it's quite in keeping with the period and another thing that I can have a bit of fun designing. There's one more tricky job to get past and that's the welding of the saddle support block to the nearside of the gearbox. I mentioned this before and, after the file test, learn that the casing is cast iron so I'll need to be nice about the Jowett Jackaroo - Learned Counsel knows how to do it.

I've finally managed to grab a snap of the chassis. Learned Counsel had his back turned for a couple of minutes and I slipped into his workshop for a gander.

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He's gone gadding off to Spain for the next couple of days and what he doesn't know is that I'm collecting the new radiator on Friday so by the end of the weekend that should be on my chassis, thereby maintaining my pole position.

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