SHM

I'm just curious what the differences are between the hydro formed aluminum space from in my C6 Z06 compared with the one in the new C7 cars? Did they increase torsional as well as beam stiffness? Increase or decrease resonance frequencies, etc.?

Clairvoyantwolf

I can't directly answer that question of the C6 Z06 frame compared to the C7 Z06 frame, but there is a SAE paper on the C6 aluminum frame which can provide some answers indirectly (#2005-01-0465 there is a preview of the paper on the SAE website http://papers.sae.org/2005-01-0465/).

In short the C6 Z06 frame major advantage or the steel C6 frame was reduced weight. The C6 Z06 frame is in fact slightly LESS stiff than the steel frame. Another aspect of the Z06 frame is that it had to fit the packaging and requirements of the C6 and be able to use the same line.

I have not read any papers on the C7 Z06 frame, but GM has stated that the C7 aluminum frame is noticeably stiffer than the C6 steel frame as well as lighter (though possibly heavier than the C6 Z06 frame). It of course doesn't need to fit the C6 packaging requirement nor go down a C6 line. It can reasonably be assumed that the C7 frame is better optimized since it doesn't have to fit C6 dimensions.

Hope that helps.

SHM

Thanks for the reply, Clairvoyantwolf. That's very interesting. I was under the impression the aluminum space frame was stiffer than the steel frame, but, I was wrong. Aluminum IS a softer material. So I'm not too surprised. It's also interesting at how the aluminum frame had to fit the C6's form factor. I stand corrected on that one.

I was hoping to read that paper you sent a link for, but, when I clicked on the link, I got a:

Not Found

The requested URL /2005-01-0465/). was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

I assume this page was either removed or moved elsewhere. If you have a updated link available, I'd be really interested in reading this. I'm a first time Corvette owner and I'm trying to learn as much about my car as I can.

Clairvoyantwolf

Hmm, that's odd, the link works for me. I even did a search for the paper itself, SAE 2005-01-0465, and found the same link through google.

Just so you know the paper at the link is only a preview that has "part" of the paper. But, yes I was quite surprised that the C6 Z06 frame is less stiff than the steel frame. From the way GM talked it seemed the opposite. But major take aways from the paper are basically what I said. The design goals for the Z06 frame were a test class lower that the C6 steel frame (about 140 lbs) while only losing 7% in stiffness with no distruption of the assembly line. They managed to get the target weight with only a 5% loss in stiffness by using the solid roof structure as a load path.

The C7, to answer your question, is 57% stiffer than the C6 steel frame and 99 lbs lighter. So, to put it altogether, the C7 aluminum frame is cheaper than the C6 Z06 frame since it is made and designed in house as well while also having production costs spread through every C7. It is also drastically stiffer than C6, while only weighing 41 lbs more than its C6 Z06 counterpart. Seems a pretty good trade to me.

More sources: http://articles.sae.org/11744/

SHM

I'm always asked why my car is only available with a fixed roof. Now I actually have a real answer for them. With the C7's frame being integrated into the design, I can see why it's less expensive. Plus, it's also a big reason why the new Z06 is available as a convertible.

I agree. The design of the C7's aluminum frame being integrated with the new design saves cost over the aluminum frame in my car, and is significantly stiffer without further wait penalty. Definitely a great trade-off to help keep the car on the affordable site.

This S A E link. This link works fine.

Now the other link is working fine. Don't know why it wasn't working before. But, it works now. Bizarre...