Alfa powered build.

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ChrisS
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Re: Alfa power build.

Postby ChrisS » 02 Jan 2018, 01:43

I've constrained myself a bit with my choice of wheel arches, but honestly, with the power I'll have on tap and the use I intend, anything bigger than I propose would probably be a bit daft.

As soon as I've done some measurements at the back I'll get the wheels on order. Having them to hand will help I think.

Had an interesting conversation with a friend over the holiday. He has suggested I talk to someone he knows who uses spray poly for prototyping etc. The chap does most of his work for film & TV but is apparently a model maker at heart and despite having worked on some proper blockbusters, is still happy to spend time on small one-off jobs for enthusiasts, at enthusiast prices. I'm thinking about the nose cone. I'll put up some posts if anything worthwhile comes from it.

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rennkafer
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Re: Alfa power build.

Postby rennkafer » 02 Jan 2018, 10:46

Ya, my intention for mine is it will be a dedicated track car so I'm going for maximum mechanical grip (and we'll see what happens on the aero front). For my intent the larger wheels make sense, for a dual purpose or street only car it makes less.
Bill J

ChrisS
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Re: Alfa power build.

Postby ChrisS » 12 Jan 2018, 04:26

Well, looks like I’m on my own with bending these tubes. So, another question for Kurt please...the lower rear curved tubes, are they on a fixed radius and if so, could I ask what it was please? I like the way the back looks and want to replicate it as closely as I can if possible.

Cheers

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Re: Alfa power build.

Postby Midlana1 » 12 Jan 2018, 07:21

Which tube specifically? A pic is probably best. At the very back end of the car down where a diffuser would go? Since it's a track car, will there be a diffuser?

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Re: Alfa power build.

Postby ChrisS » 12 Jan 2018, 12:50

Hi Kurt. This piece, the curved square section tubes at the sides.

lower_panel_fab.jpg



My car will be road use only, it's Bill who is doing the track focused car.
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Re: Alfa power build.

Postby Midlana1 » 12 Jan 2018, 13:09

I'll measure it later today. It's just for looks, so whatever looks good to you is fine.

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Re: Alfa power build.

Postby Midlana1 » 12 Jan 2018, 16:01

Here you go. 20" from the bottom edge to the back "bumper". It's constant radius and bows outwards 3.3" at the widest point. Sorry for the crummy pics. The piece appearing to hang loose is where I cut off the lower half of it after it became damaged in the "big off" at Willow Springs.
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ChrisS
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Re: Alfa power build.

Postby ChrisS » 13 Jan 2018, 01:34

That's perfect, thanks for doing that Kurt. Really handy pictures for my collection too :)

I intend getting back out in the shed today so now I can tackle this piece that has been bugging me all over Xmas.

It's a shame about those lower sections being damaged, I really like they way they finish the lower tail profile off, although I am wondering how I can make them 'inspector friendly' for mine as the test over here is picky about minimum radii on bodywork etc. Not sure how they'd feel about a single thickness of sheet protruding. Probably have to put some sort of trim piece on it to blunt it.

ETA. The magic of maths tells me that for a chord of 20" and a height (or more formally the sagitta) of 3.3", the radius is 426mm, the arc length is 544mm and the included angle is 73 degrees.

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Re: Alfa power build.

Postby ChrisS » 14 Jan 2018, 13:07

Finally back at it. Not an awful lot done today, but something is better than nothing. Finally got those curved tubes (almost) done. I reckon I spent longer trying to find another way to do it than I actually spent doing it..... IYSWIM.

Made a template from some old kitchen worktop - cut out inner & outer pieces so I could clamp the tubes between them. Cut 2/3 of the way through the tubes every 20mm then bent them to shape. Clamped them between the pieces of worktop and tack welded, then finish-welded all the cuts. Both pieces fully welded, one piece partially cleaned up. No doubt more luck than judgement, both pieces are identical curvature.

I'll finish them off tomorrow then move on to the next step.

Curved square tubes.jpeg


I'm hoping I can bend some 22mm round tube using my plumbing pipe bender. It should cope OK. Slightly annoying is that I was offered a much bigger pipe bender for free some time ago that had dies for 20mm & 25mm tube. I turned it down as I thought I was finished bending steel conduit and didn't want to store the thing. Doh.
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Re: Alfa power build.

Postby ChrisS » 15 Jan 2018, 02:00

My latest ponder is whether to make the rear 'frame' bolt-in or not. Mainly I'm guided by the thought that Kurt tends to do things for good reasons. Other than a wee bit more work initially, part of which I have already done by fitting threaded bosses into the ends of the top rear tubes, I can't really see any reason not to make it bolt in.

Thoughts either way anyone??


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