Since the front control arms needed nothing more than ball joints, bushings, and cleaning to be perfectly serviceable, the adjustable upper control-arm shafts from VB&P are another "extravagance." They're designed to allow a wider range of caster adjustment, so that desired camber settings can be implemented without having to compromise caster settings.
Although the frames of most C4s don't distort enough to make desired caster and camber settings difficult or impossible to achieve, there is the occasional car that is a problem child. An extreme change in ride height, a damaged frame, a suspension component alteration, or some combination thereof can create alignment issues. Establishing the settings recommended for daily transportation is rarely a major challenge, but the aggressive caster and camber settings typically used for autocross and race track adventures are a different matter. With adjustable shafts, future experiments with caster/camber settings will be easy to perform.
The third part of our suspension upgrade is a new wheel-and-tire combination. We selected Sport Edition V6 wheels and Dunlop Sport 9000 tires from the Tire Rack. The Sport Edition V6 wheels are obviously a "tribute" to original equipment C6 wheels, and that fits in nicely with our high-tech update theme. As for the tires, we've had nothing but excellent experiences with Dunlops in the past, so we selected 275/40ZR17s mounted on 17x9.5-inch wheels for the front and 285/35ZR18's mounted on 18x10.5-inch wheels for the rear.
Now all we have to do is get the powertrain finished so we can go for a test ride. That won't happen for a few months, but in the meantime, we have plenty of other things to keep us off the streets and out of trouble. Stay tuned.