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PostPosted: May 13, 2015, 10:09 am 
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Polyester fiberglass and aluminum have about the same thermal expansion rate so you shouldn't get delamination from temperature differences. If adequately fastened to the fiberglass, the aluminum, being stiffer, will absorb more stress. Appropriate because it is stronger.


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PostPosted: May 14, 2015, 12:06 am 
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I'll admit I'm amazed that fiberglass would have a similar coefficient of thermal expansion to aluminum. If nothing else wouldn't the fiber to resin ratio change it fairly significantly? I would expect it to be roughly half the expansion of aluminum, depending the grade, but I'm an accountant not an engineer, so take this as just a broad question.


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PostPosted: May 14, 2015, 10:29 am 
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Quote:
I'll admit I'm amazed that fiberglass would have a similar coefficient of thermal expansion to aluminum. If nothing else wouldn't the fiber to resin ratio change it fairly significantly? I would expect it to be roughly half the expansion of aluminum, depending the grade, but I'm an accountant not an engineer, so take this as just a broad question.


It is also more related to the lay of the fibers, so you can't use one number with any style weave. The CTE is much higher in the Z axis than the reinforced X-Y axis. (the before info is based on CTE of FR-4 circuit boards)

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PostPosted: May 14, 2015, 11:08 am 
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It is also more related to the lay of the fibers, so you can't use one number with any style weave.


The difference is especially large between fabrics that are woven as opposed to unidirectional of one type or another. The weaving makes the plastic a much bigger part of the equation, since the fibers are changing direction at each step of the weave.

Metal will be weaker than the fibers so there is no real point to adding it to composite. You may also run into bonding problems long term. The real problem is how would you know? Your designing something, going a route like just tossing in layers of aluminum or mesh amongst your fibers puts you into Research & Development. That requires testing and math etc. or just being willing to accept failure.

Going established routes, like steel tubing, aluminum sheet or fiber composite means you can use industry experience. Finding and using the experience is easiest for steel tube, then aluminum sheet and lastly fiber composite.

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PostPosted: May 20, 2015, 8:29 am 
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Location: Raleigh, NC
A lot of changes recently, main one being the drivetrain. I had an opportunity fall into my lap which I fully plan to take advantage of and will significantly speed up my timeline to build this thing.

Because of the drivetrain change I had to completely reconsider my donor suspension parts as well, and I simplified that substantially too. Things are looking up all the way around.

Last night, finally, I mocked up a floor tub in CAD. I'm liking it! Needs tweaking and I have to verify some dimensions but overall I'm very happy with where this is going. Once I get some dimensions on the new drivetrain I can finalize the back end of the chassis.

Mentally this is largely figured out, so I guess I'm about 1% of the way to completion? I can't wait of have it all drawn up and ready to build...having donor parts available in the garage will be a fantastic start.

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PostPosted: July 7, 2015, 9:53 am 
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I will have to keep an eye on this one, it is similar to what I want to build except I have always planned to use a 2g Eclipse turbo and go a little narrower.


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PostPosted: November 5, 2015, 4:05 pm 
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Location: Raleigh, NC
I've decided to scrap this project for multiple reasons. Every day I think about building something...anything...that I could post up here but it's just not in the cards right now. Not enough time, nowhere near enough money. and I'm not in the right place.

Some time in the future I'll come back to this idea. It most definitely has not left me. But there are more pressing issues unfortunately.

A mod can close this up if they'd like

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PostPosted: February 9, 2016, 8:20 am 
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As hard as I've tried I just can't leave this idea alone. Maybe some day I'll have something viable...my current thinking is on a better track.

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PostPosted: February 9, 2016, 7:25 pm 
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Collect parts, collect tools, fill notebooks with drawings. Work on small things that you have room for.

The goal is a completed car, but what you learn along the way is valuable in itself.

The street rod guys don't start poking fun until someone has been working on a project more than 20 years...


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PostPosted: February 9, 2016, 9:28 pm 
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Like TRX said collect what you can work on your plan keep your eyes and ears open you might be surprised what you can find for free or cheap if you ask around or what you may be given in exchange for helping someone out. Some tools can be borrowed. Craigslist free section can hold some nice surprises as well as freecycle. And you might be surprised what fits under a bed. My mother always said if you want something bad enough you find a way. Don't give up.


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PostPosted: February 10, 2016, 7:59 am 
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factorypartsjoe wrote:
My mother always said if you want something bad enough you find a way. Don't give up.
Never met the lady, but I like her! And she's right, Anavrin. Keep plugging away at it, no matter what "it" might be, and you'll get there or at least have a helluva trip to talk about later. I know this big ol' [Intellectually Defecient] redneck well driller in Florida that built a race car. Who'd a-thunk that could happen? And found a bunch of new friends along the way... Remind me to tell ya all about it later. Point is, keep going, no matter how small the steps are. Half a micron is progress.

:cheers:
JDK

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PostPosted: February 10, 2016, 8:41 am 
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Absolutely right Gonzo progress is progress no matter how small. Learning and making friends along the way is a great thing.


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PostPosted: February 10, 2016, 12:31 pm 
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Thanks for the words everyone, it is much needed and much appreciated.

When I look back and realize I've been at this for over 2 years off and on it's a little unbelievable. But there it is...

Current direction has me going a bit more traditional but still doing my own thing.

I ended up selling my planned donor car due to an engine that was on its way out and a list of maintenance items that was more than I wanted to put into that car. Replace it with...another mazdaspeed3. A lot fewer miles and a few years newer...plan to keep this one in better shape and don't want to use it as a donor.

The list of workarounds necessary to run the mazdaspeed drivetrain was extensive and a lot of kinks would have needed ironing out. The planned swap to the audi drivetrain would have solved a number of the problems but basic maintenance and manual transmission conversion of that engine was a bill in the thousands before I ever welded two tubes together so I scrapped that idea.

A couple weeks ago I started thinking and came up with a new plan and I've already run roughshod over all the problems that kept the mazdaspeed from being a viable option.

New plan will put a ford 302 in front of the driver, a transmission firmly in the middle of the chassis, and a ball with some gears in it at the back. Mark VIII rear diff, axles, and knuckles with cobra hubs (for 5x4.5 pcd). Miata front spindles with FD hubs/bearings (for 5x4.5 pcd). I already have a miata steering rack (2 actually...I think) and column along with a set of rx-7 4-pot calipers for stopping.

And with that it should all just....work. No tricks for the ABS, no rocker arms for reversing shift cable pull direction, no electronic keys to mate to the dash to mate to the ecu just to turn the engine over, no packaging issues using a seriously wide 4cyl with transmission.

I want to keep the chassis shape roughly the same because I like it. I've done enough research at this point to know how to put everything together I just have to figure out the details of connecting it. I had some brain waves at 2 am this morning and fired up Solidworks to lay out some toobs and the direction is better than it's ever been so here's to hoping it all comes together!

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