C4 Corvette Suspension - Project C4orce Gets A Three-Way Upgrade

The "Suspension" Was Killing Us, So We Grabbed A New Shopping Cart

Dave Emanuel Jun 14, 2007 0 Comment(s)
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If you have a keen eye, you may have noticed that some of the suspension components shown in the photos covering our brake upgrade looked much like some 70-plus-year-old actors and actresses-much too good considering their age and mileage accumulation. That's because work on a vehicle often progresses at a different pace than the editorial covering that work. It obviously makes little sense to remove the brakes, install replacements, and then remove them again to work on the suspension. So while he was doing the brake upgrade, Trey Hanson (of SpeedHound Performance) also cleaned up some suspension components and replaced others. It's obvious from the Project C4orce photos that the entire car is currently a work in progress. Furthermore, these photos were shot over an extended time period, so the state of cleanliness, or the lack thereof, may be inconsistent.

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Mr. Clean's front-end rework included removal of grease, grime, and who knows what else; painting and installation of new ball joints, tie-rod ends, bushings, and shock absorbers. Cleanliness doesn't do much for performance, but it makes a tremendous improvement in appearance, and also eases repair and modification work.

After any vehicle has been driven 100,000-plus miles, the condition of various suspension components is suspect at best. Obviously, mileage takes its toll, but sometimes that isn't entirely apparent. All components don't wear at the same rate, and band-aids applied by a previous owner can often mask or disguise a failure that's just waiting to happen. Unless the previous owner kept records and passed them along with the vehicle, the most sensible approach is to simply replace all the normal "wear items" in the suspension. On the other hand, if you have documentation that some of the components were replaced in the not-too-distant past, it doesn't make a lot of sense to replace them again.

For Project C4orce, we started our suspension shopping list with tie-rod ends, and added upper and lower ball joints, control arm and sway bar bushings, shock absorbers, and plenty of degreaser. Although we'd do much of the cleaning after removing individual components, wrench turning is much more pleasurable when you don't have to continually wipe a grease/brake dust/road grime stew from your hands. Hanson chose to avoid use of harsh "industrial strength" engine degreasers, which often remove more than grease, and leave a residual odor that hangs around longer than grandma's perfume. Instead, he used more environmentally friendly cleaners and (water) hose pressure to remove the bulk of the grease stew. Then, he bead blasted or solvent washed the individual components.

After completing the clean-up work, Hanson, who is now known as Mr. Clean, replaced the ball joints, tie-rod ends, and control arm bushings with new parts from Vette Brakes and Products (VB&P). We elected to upgrade to polyurethane bushings rather than stock rubber replacements. Although they're slightly more expensive, they offer superior performance and durability.

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QA1's double adjustable shock absorbers create a whole new set of opportunities for suspension tuning. Compression and rebound rates can be altered by simply turning the appropriate knob.

Like VB&P, most Corvette parts suppliers offer suspension kits as well as individual components. If you're planning to do a complete suspension rebuild, compare the prices of kits and the individual components included. Sometimes complete kits offer an attractive cost savings.

To complement the suspension rebuild, we added a set of QA1 double adjustable shock absorbers and VB&P adjustable upper control-arm shafts. These parts will not figure in our $15,000 total build budget because they're considerably more expensive than a number of perfectly acceptable alternatives. That doesn't mean we've scrapped the original premise for Project C4orce, only that we have other plans for the car after the original project is completed. Another consideration is that in addition to generating a cost blueprint for a high-tech C4, our plan is to use the project to develop and highlight a variety of unique products. So even if you have no plans to alter your C4's powertrain, Project C4orce will still have some items of interest.

The QA1 shocks are of particular interest to anyone with a race-oriented or true dual-purpose C4. The capability of adjusting both compression and rebound allows the shocks to be optimized for virtually any type of driving environment and road condition. And since adjustments are made by rotating easily accessible external knobs, shock settings can be quickly altered to suit widely different driving conditions. Switching from optimum race to optimum street settings can literally be accomplished in a matter of minutes.

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Hanson and his bushing machine also attacked the rear suspension. As in the front, we used polyurethane bushings for improved performance.

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.

Sources

QA1 Motorsports
Lakeville, MN 55044
800-721-7761
www.qa1.net
Vette Brakes and Products
www.VBandP.com
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