In The Beginning
In the first installment, we addressed the research and planning for our project, including the up-front decisions, the car search, the project and building plans, initial budgeting, and our objectives and theme. In this installment, we will cover the chassis choice and the suspension.
Our main theme is to combine the first year for the Z06-model Corvette with late-model Z06 components, especially the LS7 engine. Our main objectives are to improve the handling, ride, braking, comfort, and performance, while retaining the original classic design. The car will be built with an emphasis as a show car, but it will also be driven, and that has driven our choice not only of components, but also the level of detail and finishes used. When you see the level of detail that we have taken things, you may feel you wouldn't plan to go to the lengths we have. You may even think we are a little crazy . . . but that's just an unconfirmed rumor. However, what we are building is in line with our objectives and vision for the car. The level to which a car is taken will have a huge influence on the project timeline and the cost. There is an almost endless variety of choices to make on this aspect that needs to be factored into your planning. While most folks may never plan to go to this extent, nevertheless, you should find the comments on choices, the details of the components used, and the assembly process of interest should you be contemplating building a car of this type.
Chassis: Choices, Options, And Finishing
Choices: The choice of frame and suspension is driven by several factors. Things to consider are the condition of your current frame, the extent of ride and handling improvement you are looking for, how you plan to use the car (street versus track), and how much effort, time, and investment you want to make. The good news is there are many choices available today; the bad news is it can make the decision a little more difficult. The Resource Guide in our February 2007 issue lists about a dozen sources. The choices range from changing the suspension components on your existing frame to using a new frame and suspension, such as that from the C5 and C4 Corvette. here are some things to consider when making this decision.
Condition of your current frame: We often forget that these frames can be 40-plus years old. If you've been around C2 Corvettes for a while, you are familiar with what to look for (such as the rear kick-up area) in determining its condition. To get the full benefit from a suspension change, the stiffer the frame the better. If the frame is showing its signs of age, a new frame may be a good choice, whether it is a reproduction stock-style frame or one designed to accept later-model suspension components.
Chassis design: With the C2, the frame design was changed to provide for the then-new independent rear suspension, and it was also widened to allow the passengers to sit lower in the car. To achieve this, the side framerails were placed further outboard and the X-member used on the C1 frames was eliminated. While we don't have any torsional rigidity numbers, it would stand to reason that some was likely lost. New reproduction frames will at least have the advantage of new metal, and the custom frames should be more rigid by design.
Cost factors: The least expensive route is in changing to an aftermarket suspension on your current frame. It's also the least involved in terms of work required. Some (such as that from Vette Brakes) provide for spring rate and ride-height adjustment. If you want to go further (such as using C4 or C5 components), the costs will go up as it involves either having your frame converted to accept these components or the purchase of a new frame designed for that purpose. There are also usually some modifications to the body, and those vary depending on your choice of frame. There are some cost offsets in buying a new frame. The major one is in selling your rolling chassis. Depending on its condition, it could help to offset quite a bit of your costs. Another factor is the shipping costs. Converting your existing frame involves shipping it twice, while buying a new frame entails shipping in only one direction. Depending on how far you are from the conversion shop can be significant.
Our choice was based on our objectives and having seen most of the custom frames in person at various shows, such as Corvettes at Carlisle. For us, a major factor was we like to do something different with each car. Our '67 used the Vette Brakes "Performance Plus" system on the original frame, and the '62 used a Car Creations conversion to the C4 suspension using the original frame. For this car we looked at chassis design for strength, build quality, use of late-model Corvette components, body modifications needed, cost, and how it looked. For us, the round-tube frame had all the right elements (maybe it's also the racing heritage of that design that appeals to us), and that led us to SRIII Motorsports (www.sriiimotorsports.com). Mike Stockdale has done a great job in his design, and the build quality is top notch. His frame uses the stock body-mount locations, the stock bumper-bracket mounts, and the stock fuel-tank cross-member. He also uses QA-1 coilover adjustable shocks that we wanted to try. His customer support has also been outstanding. While we don't yet have on-road experience since the car isn't completed at this point, the feedback from those who have used his frame has been positive.