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  #91  
Old 10-07-2010, 07:32 AM
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"BUT the development of advanced shocks has led to a massive reduction in size and so the space is readily found for coilovers for performance cars."

That is all I was trying to add something to, size. I work with shocks, I see a ton of stuff coming in and out of my work and their sizes vary greatly. Nothing suggests to me that "modern" one is more or less compact because its newer or older. Corvette damper is TINY compare to something off a 911. But are they that different in how modern they are? You size your shock size base on damping need and mechanical load cases. When you got a Caterham with nice motion ratio, short travel, and less load needed, you can build a small damper. That kind of condition may or may not be available in all cases, and damper is definitely not the first thing you design and pick when one is designing any car, let alone a packaging conscious passenger vehicle.

Yes sticking to tradition for the sake of it sucks, but sales and marketing drive that anyway(blame the customer? lol). Although I am not sure if that is necessarily the case in Corvette's design. One thing that is somewhat unique still in Corvette is that its still a body on frame car(another tradition maybe?), and most of the structural packaging is still in the frame rails. The leaf spring applies their load to the pivot and thats supported across the frame, and they can potentially(not to say they did, its my guess) have a much less reinforced damper mount that only takes damping load that cantilevers off the top of the rail in its own mount. The race car is built much different structurally since much of the frame was replaced/reinforced with cages and tube frame, they can get much better load path compare to the stock chassis without worrying about the same packaging requirement. Merit of sticking with body on frame instead of unibody? That I have no idea, though it does allow them to make all their models(hard top, convertible...etc) and not sacrificing structural rigidity with or without roof... Again, my best guess....
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  #92  
Old 10-07-2010, 07:58 AM
culver culver is offline
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Actually the Corvette isn't body on frame. Body on frame is meant to indicate you have a more or less complete passenger compartment dropped onto a rolling chassis.
http://www.imperialclub.com/Yr/1966/...bove-frame.jpg
That is typical of trucks. The Corvette is more like a Ferrari or Lotus in that the body panels are attached to a frame and the interior is attached to a frame.
Lotus: http://www.lotusespritworld.com/imag...se_chassie.jpg
Ferrari F360: http://www.ferraricars.org/img/ferra...ructure-02.jpg
C6 Targa:http://www.seriouswheels.com/pics-20...s-1280x960.jpg
Note that the central tunnel is a key part of the Corvette's structure and to this end is closed on the bottom.

The C3 was the last truly body on frame Corvette.

The racing Corvette's use the same basic chassis but add a cage and some other parts. Do keep in mind that the Corvette chassis is rather stiff. The base C6, which as a targa does not have a structural roof, is about as stiff as a Ferrari F360 (which has a roof). The Z06 and ZR1 are stiffer thanks to the inclusion of a structural roof.

Last edited by culver; 10-07-2010 at 08:06 AM.
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  #93  
Old 10-07-2010, 08:57 AM
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Not unitized body though, thats what I am saying. The "typical" car unitbody will have a front shock mounting point, inside a structural wheel well. In Corvette's case that would endup taking up the space by the engine, which might not have the room for that reinforcement:

Road car: C6 under the hood image by vettnutt on Photobucket

Race car:
http://lotpro.com/blogphotos/General...20C6.R%201.jpg

Note the 2 truss structure that comes out from the passenger cell to the shock pickup on the race car, on the road car a bunch of auxillary stuff is packaged there. For a car typically with unitize body, the structural reinforcement there would be substantial for a spring/damper unit mounting...(DB9, I believe)

http://www.cyberweld.co.uk/pictures/...e/chassis_.jpg

For Corvette the use of the transverse leaf loaded to the frame rail simplifies a lot of the design, and you are utilizing whats already there, instead of building more structure to support it...
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Last edited by RacingManiac; 10-07-2010 at 09:00 AM.
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  #94  
Old 10-07-2010, 10:14 AM
culver culver is offline
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OK, yes I completely agree that the Corvette isn't a unibody. GM, just as Ferrari and Lotus, had to deal with the question of how to make a chassis with by automotive standards low tooling costs. The traditional dies used to make unibody cars are VERY expensive (as I'm sure you are aware). This is why the Corvette (and Lotus and Ferrari) has used fiberglass then later sheet molded composites to make the body. The low pressure tooling is far cheaper than the tooling needed to make a traditional stamped body part. It will be interesting to see if the hydroformed body panels used on the Solstice find their way onto the next Corvette. That process uses only a single sided die (vs two for a stamping) and the dies don't have to be as hard as with stamping. Anyway, the body panels on a space frame construction is common in lower volume cars because the tooling costs are lower.

You are also right about the extra triangulation in the racing Corvettes. It's understandable that any time you take a street car and turn it into a race car adding some extra bracing is basically a must even if the base chassis is well designed. Ironically I was going to include that exact same race car chassis picture!
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