John Shiels

I read aluminum is going to be eliminated in the frame on the C7.

1991Z07

Carbon Fiber?

acrace

I thought that I read somewhere that a person going through the plant on the buyer's tour was told that there was an area being renovated with the purpose of bringing the aluminum frame manufacture in-house?

We'll just have to wait and see . . .

c4cruiser

What ever happened to all that area that was used for the Caddy XLR assembly line? Seems that if it's not in use, there could be space for frame fabrication. Robotics would the way to do the bending and forming then on to a TIG welding line. Building frams in-house can certainly solve any delivery issues and transportation costs.

I would think that carbon fiber would certainly add strength while taking weight off, but is there current technology to build a car frame from carbon fiber? And how would body shops be able to do frame repairs to cf??

And what would that do to the cost given the 518 Z06's made in 2010 and 904 made in 2011? I could almost see a $100K C7 Z06

Also, is it possible that the front cradle could be going away from magnesium to aluminum? That may be a cost-saving deal and it may be easier to fab the cradle from aluminum. Parts of the body are aluminum and carbon fiber is used in part of the Z06 frame already.

SteveDoten

Magnesium has been used since 1997, about 250,000 Magnesium column/pedal supports installed in the C5

Mg symbol on each one, I believe it was used as more of a NVH absorbing metal vs. aluminum

good point on the XLR, what's going on over there?

CF? I hope not

where are the C6Z frames built?

I saw the C6 frames welded at BG years ago, not sure if the hydro form process was there?

TLGunman

Carbon tubs are used on a few exotics, Pagani, Mosler, Koenigsegg...I don't think the average Corvette buyer would like it...or at least the cost that goes along with it.

69427

I've been interested in the technical details of the Z06 frame. Anyone have a source they can recommend? (Struck out finding anything of substance on the search function.)

Thanks.

acrace

SAE papers 2005-01-0465 and 2005-01-0466. Both written by GM body structures engineers and Alcoa. Each paper's about four to five pages and discusses material properties and selection, analysis criteria techniques, manufacturing, and a little bit about dimensional control.

They're part of a SAE publication - Chevrolet Corvette New Vehicle Engineering and Technical History - which came out when the C6 Z06 was introduced, and has both a collection of historical SAE papers and papers specific to the C6 Z06. SAE publication PT-118. You probably can find it through sae.org.

It was pricey when it came out (my copy shows a $129.95 price) although I believe the price did come down. Still very interesting for all of us automotive/materials engineers.

Update - you can get the book for $20 through SAE:
http://books.sae.org/book-pt-118

List of papers in this book:
http://www.sae.org/servlets/PaperEve...PROD_CD=PT-118

At this price, it is a "must read" for Corvette/engineering enthusiasts.

acrace

There was a pretty good historical view on carbon as used in tubs in the April, 2011 Road & Track, as written by Gordon Murray. When the latest McLaren came out, there was a flurry of carbon-related articles.

Seems that the key to getting the cost of carbon usage down is not only the material cost, but getting manufacturing/process technologies down so that the cycle times (and tool utilization) become realistic.

acrace

Mg has been used by GM in (primarily) cockpit/instrument panel cross-car beam structures. The ability for the cross-car beam to be cast/machined offered dimensional advantages over a conventional steel welded cross-car beam and at a weight savings. NVH benefits came from stiffness improvements (steering column NVH is an important design criteria). Disadvantage for magnesium in vehicle components is its brittle behavior. That's why, in instrument panel structures, when a mag beam is used, steel crush brackets are often used to absorb crash loads (like knee impacts).

The first gen MINI also used a mag cross-car beam.

John Shiels

sorry I didn't post it they said it was going back to steel hydro formed frames for all Corvettes.


this was from MT

Reports suggest the Corvette may use an aluminum spaceframe, with the body composed of a mix of carbon fiber and fiberglass. That would be expensive, but it would cut weight -- possibly below 3000 pounds in some models. Like all automakers, GM is looking to cut weight from its new cars, in part to improve fuel economy, and trimming mass will also no doubt improve the Corvette's dynamic performance.

Read more: http://www.motortrend.com/future/120...#ixzz1ku4bA3Py

I guess they are all guessing along with me

SteveDoten

C5 lower xbar(material steel) is bolted to the alum. w/s frame on ends and tunnel in middle

C5 upper xbar is alum./also lower alum. w/s frame

The Mg column support in the C5 is strictly limited to the pedal/column area(not a cross-car beam)

NOTE: I'm pretty sure you are aware of the above info, but I may be confused by the use of 'cross-bar' you used as comparison in other cars being made of Mg

Thanks for the link of the SAE book above, looks like a great read, gotta get that

acrace

Most of GM's mid-sized and full-sized passenger vehicles designed in the late '90s and early '00s, such as the Monte Carlo/Impala, Aurora/LeSabre/Bonneville, and the first gen CTS, used a full magnesium cross-car beam. To the beam would be mounted the column, the air bag, electronic modules, plastic retainer, etc.

Most of their competitors used multiple welded steel stampings/tubes to form a similar function.

Think of the cross-car beam as the "spine" of the entire cockpit module. I haven't been involved with cockpit engineering for a few years, so I don't know the current GM (or competitive) vehicles.

SteveDoten

I have installed/removed the front C5 lower dash bar, it's steel

the Mg part mounts the pedals and column, the steel bar is also bolted to it

69427

I appreciate it!

AU N EGL

Nope may not be a C7 Z06.

Shaka

This is what I hear from a collector of rare Corvettes in Palm Beach FL. with an inside into GM. All C7 chassis will be modified cary over aluminum ZR1 chassis. Seems that the tooling for the steel chassis has a 20 000 unit run left. All chassis deimensions will be the same. The C7 will be a rebodied C6 and the complete redesigned C8 is at least 3 years beyond that. Only thing that concerns me is if there will still be United States at that time. Mechanically, they will be the same also, with the usual Corvette improvements.

AU N EGL

Nope. C7 is all new. no sense in changing in three years again. Keep a design at least 10 years min is the idea

Shaka

Don't know if we know that for sure. It's pretty cheap to change a plastic body. We will find out at the next Detroit Auto, I guess.

travisnd

I really hope the C7 isn't some stop-gap, warmed-over C6, wait for the C8 car...