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Old 03-07-2010, 10:52 PM   #1
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Default 5 lb deck lid.

My decklid with the bracing for the wing weighed 19 lbs. The hinges were another 4 lbs. I didn't weigh the latch mechanism, but I am going to claim it is a direct offset to the weight of the aluminum hood pins.

The deck lid that was vacuum formed for me weighs 5 lbs. That is including the inch and a half by 1/8th aluminum I used to make the front edge a little stiffer.

Total weight savings 18 lbs.

My existing deck lid was, shall we say, "challenged". Multiple holes, some dents etc. They warned me that all this would detract from how well the lid turned out. They also suggested that I spend some time making blocking for the underside so that it wouldn't risk being deformed when they vacuum formed the new lid. Did I listen? Well sort of. I did minimal prep on the surface and zero blocking. They were kind enough to do some of the blocking for me. If you look closely you can see where it would have turned out better if I had listened. However, all that being said, I am really pleased with how it turned out. If I were to do it again, I would listen to the expert of course. It is just barely rigid enough and might have been a little better if we had gone with a thicker material, but then it would have weighed more.





How do you mark where to drill the holes in the deck lid so they line up with the ones in the car for the hood pins?
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Old 03-07-2010, 11:02 PM   #2
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Vortex generators?
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Old 03-07-2010, 11:08 PM   #3
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Looks like it.

What does generating turbulence behind the trunk lid do? decrease drag?
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Old 03-07-2010, 11:09 PM   #4
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cool
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Old 03-07-2010, 11:11 PM   #5
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Needs more red!

That thing is the hotness. You know where to send the second copy, right?
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Old 03-07-2010, 11:19 PM   #6
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Quote:
Originally Posted by kotomile View Post
Vortex generators?
Yes
Quote:
Originally Posted by Full_Tilt_Boogie View Post
Looks like it.

What does generating turbulence behind the trunk lid do? decrease drag?
That is the theory. Not sure what it will do with the wing and with or without a diffuser, but that was the prototype that came out the best. Testing will tell. Anyone have a wind tunnel I can borrow?

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Originally Posted by webby459 View Post
Needs more red!

That thing is the hotness. You know where to send the second copy, right?
I don't think ABS comes in red, but I can check.
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Old 03-08-2010, 09:18 AM   #7
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Quote:
Originally Posted by Chris Swearingen View Post
How do you mark where to drill the holes in the deck lid so they line up with the ones in the car for the hood pins?
Temporarily mount the shaft where its going to be, cover the tip in some tape and slap some white out on the top of it. Place the trunk lid on how it would normally sit, then turn it over and drill where the white out marks are.

As long as you do it carefully, you really cant **** it up.
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Old 03-08-2010, 09:40 AM   #8
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Did you make any extras?
Are you going to mount the wing to the rear quarters?
It looks great
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Old 03-08-2010, 09:47 AM   #9
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Originally Posted by mikewolf View Post
Did you make any extras?
Are you going to mount the wing to the rear quarters?
It looks great
No,yes, thanks, wait until you see the new wing.

Version 1.0 of the new mounts

Version two will be more like


And the new wing looks a whole lot like
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Old 03-08-2010, 09:54 AM   #10
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So what happened to your old wing? :ninja:
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Old 03-08-2010, 10:11 AM   #11
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I've never seen vortex generators shaped like those. From whence (I like that word) did you derive your inspiration for that shape?
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Old 03-08-2010, 10:12 AM   #12
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So what happened to your old wing? :ninja:
Based on the number of times I have been asked that question, I sold it way to cheap.
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Old 03-08-2010, 10:18 AM   #13
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Based on the number of times I have been asked that question, I sold it way to cheap.
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Old 03-08-2010, 10:50 AM   #14
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I've never seen vortex generators shaped like those. From whence (I like that word) did you derive your inspiration for that shape?
You guys want all my secrets.
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Old 03-08-2010, 11:41 AM   #15
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those are airtabs.
Home : Airtab



Also... Chris, you could still "glass on" some foam structure to the underside to help support the trunk's flimsiness.
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Old 03-08-2010, 11:57 AM   #16
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Was it a ridiculous amount of work to make that? I could see them being popular considering they are so light.
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Old 03-08-2010, 11:58 AM   #17
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Quote:
Originally Posted by y8s View Post
those are airtabs.

Also... Chris, you could still "glass on" some foam structure to the underside to help support the trunk's flimsiness.
So much for secrets on the internet.

I used a inch and a half by 1/8th aluminum strip riveted to the front to help it hold the curve better.

This whole project started as a "can I make one out of fiberglass". The thermo/vacuum forming made a much nicer product with a lot less effort (on my part) and was lighter than what the fiberglass would have weighed. Commercial fiberglass deck lids are in the 8 lb range with carbon fiber in the 7.5 lb range. I am making a really conscious effort to reduce weight this year, so the need for more material will have to be pretty obvious for me to consider it. Between the aluminum, the careful placement of the hood pins to generate just a little tension and the stiffness the shape itself lends I think I am going to be okay. I can't wait to get out and test it.
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Old 03-08-2010, 12:06 PM   #18
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Originally Posted by icantthink4155 View Post
Was it a ridiculous amount of work to make that? I could see them being popular considering they are so light.
The amount of work in the one-off prototype wasn't that bad, especially since a friend did most of it. To make a "production version" I would have to make him a much better mold, work out some kind of deal with airtab to reuse/resell their product, do a little more design work on the stiffness, source the hood pin components for a "complete kit" and then explain to people why the 5 lb solution is as much or more $$ than the 7.5lb carbon fiber one.

And then, I have to actually get setup with someone to manufacture them, work on taking orders, shipping etc etc.

I think I am pretty happy just doing the one off.
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Old 03-08-2010, 12:25 PM   #19
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Quote:
Originally Posted by Chris Swearingen View Post
So much for secrets on the internet.
This whole project started as a "can I make one out of fiberglass". The thermo/vacuum forming made a much nicer product with a lot less effort (on my part) and was lighter than what the fiberglass would have weighed. Commercial fiberglass deck lids are in the 8 lb range with carbon fiber in the 7.5 lb range.
Did you investigate the axis power racing alternative? supposedly sub-2lbs, but very expensive.

miata
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Old 03-08-2010, 12:32 PM   #20
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Originally Posted by proto View Post
Did you investigate the axis power racing alternative? supposedly sub-2lbs, but very expensive.

miata
I hadn't seen that one. Looks really nice. One day when I am rich and famous maybe....
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