Suspension: Choices, Detailing, And Finishing
Choices ::: C5 or C4 or a combination: Since we had used the C4 suspension in another car, we wanted to use the C5 suspension in front, which also provides a little more room in the engine compartment. In the rear, we considered using the C5 rear-mounted transmission/differential, however, the changes necessary to the fuel tank and rear body areas led us to go with the C4 suspension and a Dana 44 differential. We wanted to retain the stock body width, but still use the 911/42-inch-wide wheels, which required narrowing the differential carrier, rear toe-rods, camber rods, and a custom sway bar. It also required moving the rear inner fenderwells in about an inch and a half on each side. You can, however, use an 811/42-inch-wide wheel and avoid having to narrow those components. On a coupe, narrowing that area isn't a problem space-wise, however, on a convertible, narrowing the space between the wheelwells can restrict fully lowering your convertible top. Another option, which avoids having to narrow the components, is to widen the rear quarter-panels. There are sources for these quarters which will provide the space needed to accommodate a wider wheel.
Springs and shocks: There are two approaches taken by the various chassis builders. One uses the monoleaf fiberglass springs, while the other uses coilovers. One thing to keep in mind when making a spring choice is the car you are building will typically be lighter than the car the stock springs came from. Usually you will find that a lower spring rate will provide a better ride. There are sources, such as Vette Brakes, that make the monoleaf springs in different spring rates to suit your combination of components. For this project, we wanted to use the coilover spring and shock and chose the QA1 units. The front spring rate is 350 pounds, and the rear is 250 pounds. The shocks are adjustable with twelve different settings. we are starting at setting "3" as a base setting.
Detailing ::: We wanted to carry the detail for each suspension piece further than we've ever done before. First, each piece was disassembled and bead-blasted to clean it. Then began the regimen of grinding, filing, and sanding each piece to remove all the seams and part numbers and recontour to the shape we wanted. This is a good example of where the level of detail can really extend the amount of time you spend on your project; this aspect alone involved over 950 hours of our time. While some tools (such as the Multi-Mate stationary belt sander, Dyna-File II hand-held belt sander, and Dremel Tool) helped to rough out the shape we wanted, approximately 75-percent of the time involved work by hand using various files, sanding blocks, and dowels wrapped with various grits of sandpaper. Once the component was taken to a 1,500-grit level, it was then polished. This isn't something we would recommend doing and likely will never do again.
Finishing ::: After the experience (and pain) of going the route we did, good old powdercoat now appeals to us more than ever! But since we went the polishing route, we needed to look ahead to future maintenance since the car will be driven. If you do decide to go the polishing route, it's a good idea to apply some type of protective coating to reduce or eliminate having to get back in there to keep things looking good. We searched for a clearcoat that would provide protection while not reducing the polished shine. We did tests using clear powdercoat, but that reduced the shine more than we wanted. Next, we tried a POR-15 product called Glisten, which is a two-part mix, and that worked better from the shine standpoint once we found the right level of thinning and how to apply it. We used that on the transmission because it appears that it can stand higher temperatures along with being durable-a good option for that unit. However, after all that work in polishing, it still wasn't quite what we wanted as it does take some of the luster away. So we tried a new product called Chrome FX, which is advertised as a spray-on type of chrome finish. A friend, who is in the coatings business, tried it, and the early results looked promising. However, we couldn't get the final third stage to work the way we wanted. Further experimenting might have produced better results, but we were running out of time.
After all that experimenting, we decided to take the regular chrome route for appearance and durability. Actually, I guess there is no such thing as "regular chroming" when it comes to aluminum, especially for the cast-aluminum pieces. One key aspect of chroming is that its quality depends on the density of the part and its shape, which impacts the electrical flow. Forged-aluminum parts chrome well, but that's not always the case with cast aluminum. We ran into a major issue on the cast pieces where the porosity caused a problem in getting the copper to stick well and flow evenly. It looked like we were at a dead-end until we discussed the problem with Har-Conn Chrome (www.har-conn.com). They have almost fifty years of experience in coatings for the aerospace industry and had a process to seal the aluminum and get the copper to stick. They now have a new subsidiary called Anvil Power Stryke that does powdercoating.