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Fastback for a convertible

PostPosted: Mon Nov 21, 2011 9:53 pm
by Hans Efde
One day I was fantasizing about the combination of a Gold convertible and a mk3 coupe. I can't afford both, but I like the shape of the coupe very much. I was thinking about a hardtop that doesn't mimic the softtop but mimics the coupe shape. From a technical point of view there would be problems to solve, but I reckon the end result should be worth it. Realistically I don't see something happening within 5 years or so, so I put the idea to rest. Until I came across the picture below. Apparently in the MX5 scene someone had a similar idea and put the idea to work. They call it a fastback and I think it looks fantastic. Googling around I found other designs and projects by MX5 enthusiasts. Too bad our group isn't that big! Anyway here's something to drool about. Who knows in a year or 10 available for the Gold convertible.

fastbackmx501.jpg
fastbackmx501.jpg (116.64 KiB) Viewed 16102 times

Re: Fastback for a convertible

PostPosted: Mon Nov 21, 2011 10:05 pm
by Alan D.
I love the extended wheel arches, I suppose they are very Midas!

Alan

Re: Fastback for a convertible

PostPosted: Mon Nov 21, 2011 11:37 pm
by manifold
I like it Hans. Not difficult to make either.especially if someone is willing to sacrifice a hardtop to make the front part.....

Re: Fastback for a convertible

PostPosted: Mon Nov 21, 2011 11:58 pm
by Hans Efde
manifold wrote:I like it Hans. Not difficult to make either.especially if someone is willing to sacrifice a hardtop to make the front part.....


It seems this solution was also used for classic cars as Triumph spitfires. For me it's just a brainwave, but it's nice to spend a few evenings making sketches (I get so bored of just hanging in front of the tv). The waist line on a Convertible is higher than the coupe, so it's interesting to see how that translates in a proper design. With the bootlid removed you get a nice sturdy edge with proper clamping possibilities and alignment would be easy as well.
Such a fastback would convert the Convertible in a proper long range tourer, quieter, quicker and more efficient on fuel. Also handling would be better, no scuttle shake anymore. I read about the MX5 conversion that they make a carbon version for racing:
http://www.autokonexion.com/product_inf ... arkbdtbfl1

Re: Fastback for a convertible

PostPosted: Tue Nov 22, 2011 12:50 am
by manifold
To be honest I reckon you could chop the back out of a hardtop and make one quite easy. Some nice modern curves would make it pleasing on the eye....and a small integrated spoiler would finish off the boot.

Not sure your going to get rid of the scuttle shake though Hans as its a non permanent structure relying on a few pick up points....unlike the monocoque of the Coupe. It might tighten it up a little......not that I have any complaints.

Didn't they do something similar with the Lenham Le-mans conversions for the spridgets??.... or was that a more rigid structure.

Food for thought.

Re: Fastback for a convertible

PostPosted: Tue Nov 22, 2011 10:59 pm
by Hans Efde
Dimension wise it would look a bit like this:

fastbackmidas01.jpg
fastbackmidas01.jpg (54.89 KiB) Viewed 16068 times


fastbackmidas02.jpg
fastbackmidas02.jpg (81.99 KiB) Viewed 16068 times


The roof shape would be softer than of the coupe. The coupe has very strong shoulders that can't be made on the convertible. But because the waist line is higher than the coupe (the waistline of the coupe steps down at the mirror, while the waistline of the convertible follows the nose), the rear window is a bit shallower making it look slightly meaner.
The rear lip would be a big problem to get it right. The back of the car curves in quite strong and with the lip it needs to be curved back.I am not sure it will look right. But basic dimensional relations look okay to me. It won't get a saggy bottom like the Mini Marcos.

Re: Fastback for a convertible

PostPosted: Wed Dec 07, 2011 12:11 pm
by Hans Efde
I got this link from Peter, also in the GTM scene this idea has popped up:
http://www.gtmdrivers.com/forum/rossa-f ... t1757.html

Re: Fastback for a convertible

PostPosted: Wed Dec 07, 2011 2:30 pm
by manifold
Looks great that conversion on the GTM. I noted they also brought up the Lenham Lemans Spridgets.