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03-21-03, 12:18 PM #1MarkEEGuest
Transverse Leaf Springs Vs Coilover Springs - C5 Suspension Modifications
I have recently read several inquiries regarding coil over springs for the C5. The responses that I have read indicated that this modification results in a rough ride. Other resposnses relate to lowering the suspension to provide better performance.
Now you have just paid $52K for a Z06 that can knock the socks off of a GT3 Porsche and a NSX. So I am assuming that the C5 owners know more than the GM engineers by installing coil overs and/or lowering the car. Well I don't but I have studied the dynamics of a rear wheel drive, independently sprung race car and I know what parameters that I would like on a Z06. I use Bill Mitchell's Racing by the Numbers Program because I have attended Caroll Smith, Walt Preston, and Bill Mitchell's Racing Seminars, read Carrol Smith's Race Car Engineering Books, and from that I have realized the basic pricipals for suspension dynamics.0% - 60 % Zero ackerman, bump steer, ride height, roll center, roll center migration, roll center centerline mass torque arm, caster, camber, camber change, wheel spring rate, spring rising rate, and sway bar angle vs sway bar torque.
I'm not saying that given the above is all inclusive and you will know Mark Donohue's Secret Advantage but this provides a baseline. I have driven at Sears Point, Willow Springs (the fastest true road course in the US, and Brands Hatch. I by all means am not an expert but after a while these things do make sense in certain arenas (i.e. Nascar runs soft springs at speedways so the car will change its aero ride height to provide less aerodynamic downforce because the rear spoiler is out of the air stream, boy that took a while to figure out! don't think I would do this in a Z06 at Daytona.)
So where does this end up at. Well in 1976 a fireman the owner / driver, Howard Park from Lexington, Ky, which I was part of his crew ( his wife and I were the crew 1972-1977) was spnosored by L. R. Cook Chevrolet of Lexington, Ky and won B Production at the SCCA Runoffs. I remember setting up the car for Daytona, put in the big "Daytona Spring", made sure the rear halfshafts are level, and don't forget to put air in the tires before you leave the pits! To this day I don't know what all of that was about did but we won beating the Huffacker Group 44 XKE!
Now I will get to the real point of this discussion. I have suspension parameters for several race cars but to this date I have not been able to penetrate the GM Motorsports cloak of secrecy. Now we used (1976) to get parts through GM's back door with no problem (mushroom lifters etc didn't get caught but blew up three engines helping them do their R&D). So I will be more than happy to provide anyone with the suspension analysis of their C5 if I can get the suspension point data. So if you have a source of the data let me know or if you have contacts the attached file is a partially blank form for a 2002 Z06 if you have the data for any other C5 just make the changes.