Fiberglass fabrication?

[serialk11r]

I am really considering selling my FR-S and going back to an MR2 Spyder. This time I have a job and more money, so I can get a 2ZZ with 6 speed transmission, which will be a decent fuel economy improvement over the 1ZZ with 5 speed, as well as a massive speed improvement thanks to 35% more power

The one thing that is stopping me is again the hardtop issue. I don't like the OEM style hardtop because it slightly bulges out above the cabin, which pushes the template a bit higher. This matters a lot because the rear deck falls quite a bit below the template.

4 years ago when I just got my MR2 Spyder I discussed this topic with people here in this thread and this thread.

Here's the template over the softtop, thanks again freebeard:


I'm too lazy to overlay the template over this and reupload, but you can see the point of max camber is pushed back and up a bit on the hardtop:
http://autoautomobiles.narod.ru/auto...a-mr-s-tmc.gif

This also looks rather ugly since there's a bunch of hardtop poking over the windshield.

An old gentleman on Spyderchat actually made his own hardtop, but it was too boxy and no one was interested in it, sadly.

This is how his turned out:


Before he finished it though, my suggestion for the roofline was something like this:


Playing with the template overlay tool here, I was able to click the "--" button on the template one time and move it forward a few "inches" against that new roofline. More importantly, it looks really cool.

I have no fiberglass working skill so I am not going to attempt to do one of these from scratch, does anyone know how I might get a piece like that done? I think I can improvise a bit on mounting hardware, but the large chunk of fiberglass is daunting. One possibility I thought of is to buy a VIS fiberglass top, then chop most of the top of it off, and then fill it with a flatter piece of fiberglass, but that is also a terrifying proposition.

[ChazInMT]

I don't see how you are going to gain a measurable improvement by slightly tweaking the roof line there. I can see where if you put something on there that extended the roof back to the rear edge of the trunk lid that you'd get some gains, but without extending the template, I can't imagine anything other than a tiny improvement.

[California98Civic]

Originally Posted by ChazInMT

I don't see how you are going to gain a measurable improvement by slightly tweaking the roof line there. I can see where if you put something on there that extended the roof back to the rear edge of the trunk lid that you'd get some gains, but without extending the template, I can't imagine anything other than a tiny improvement.

Yeah, that has got to be correct. One of the best things I learned here at EM was about optimization. How would you optimize the shape? You could spend a lot of time and money on a piece that would change nothing. I don't want to discourage, but it would likely prove really disappointing. I have had experience with disappointing experiemnts. You have much better chances extending the template, as ChazInMT notes. Why not do that? With a hinged tail about the trunk you could retain trunk access.

[kach22i]

If you could build (have poltcarbonate cut) a wind deflector (rear window) plus also have cut a top, then the MR2 would go from convertible to Targa-like Cd numbers (better than full blown true convertible), see the Porsche 914 numbers in link below.

http://ecomodder.com/forum/showthrea...tml#post374311


Toyota MR2 Wind Deflector - Roadster / Spyder


Budget Targa Top - Super lite - Pelican Parts Technical BBS


Then again, perhaps just build a whole new rear section out of polycarbonate and thus avoid the fiberglass issues.

Lexan - Polycarbonate Rear Targa Glass? - Pelican Parts Technical BBS

[elhigh]

The Pelican Parts link includes a picture of a 944 (love those!) with louvers in the new Lexan backlight. I know the Mister Two's rad is up front but how much breathing at the rear is important? Louvers might not be a bad plan there.

[kach22i]

Originally Posted by elhigh

The Pelican Parts link includes a picture of a 944 (love those!) with louvers in the new Lexan backlight. I know the Mister Two's rad is up front but how much breathing at the rear is important? Louvers might not be a bad plan there.

This one:
Lexan - Polycarbonate Rear Targa Glass? - Pelican Parts Technical BBS


I suspect that the MR-2 is like the Boxster in that the side intakes feed the engine oxygen. This means the rear deck louvers are for radiant heat release after shutdown.

Many Ferrari owners lift the rear hatch after running (all the mid-engine models), it's their "thing".

I can see some kind of chamber (under glass area) venting being an asset on the MR-2. Does not have to be a full louver, could be a smaller vents at top and bottom of enclosure.

Hardest parts of this type of project would be making it rain tight, plus the custom bent aluminum for the polycarbonate frames will have a high level of design involvement.

Still don't have to go fiberglass in my opinion. Lots of rubber gaskets though.

[kach22i]

I found a little more information.

What year MR-2?

MR2 Products

This motor-lid was designed with function in mind: The stock Turbo motor lid does not allow enough hot air out of the engine bay with the rain-guard attached, and leaves and dirt constantly get stuck between the grills and the guard itself. Eliminating the rain-guard poses another set of problems; you get water spots, dirt, and leaves all over the engine, and water gets into electronics and in other places it shouldn't be.

This is what my friend does with his 1981 GTS 308 after running (similar to photo - injected not carb'd though)

http://www.justacargeek.com/2010_05_01_archive.html


Heat cycling of the engine is important to these folks, don't ask too many questions about it though. It's a Ferrari, gotta take those extra measures.

Another idea, from the same link as above:

[Xist]

Doesn't Lexan yellow?

[Grant-53]

Lexan can be affected by sunlight. I don't recall how it turns when exposed to UV rays.
A clear coat automotive paint would solve the problem. Shaping plastic with a heat gun is easier than dealing with fiberglass in my experience.

[California98Civic]

Originally Posted by Grant-53

Lexan can be affected by sunlight. I don't recall how it turns when exposed to UV rays.
A clear coat automotive paint would solve the problem. Shaping plastic with a heat gun is easier than dealing with fiberglass in my experience.

Maybe a UV clear coat like this one?
UV-Resistant Clear Coating - | Krylon

james