2003 Corvette Z06 Suspension Kit - Low and Pfast!

Part One: Pfadt Race Suspension and Anti-Venom turn an 2003 Chevrolet Corvette Z06 into an open-track killer

Chris Endres Jun 25, 2007 0 Comment(s)
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Photo by Jay Heath

Those who remember the summer of 2000 will no doubt recall the media blitz surrounding the original C5 Z06. Chevy made sure every car rag with even a shred of credibility got to wring out its new uber-car on (and occasionally off) the nation's racetracks and roads. The new-for-'01 Z proved an instant hit with the motoring press, and for good reason. The car offered more power, less weight, better handling, and gummier tires than the already very capable standard Corvette.

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To this day, the C5 Z06 remains a favorite among autocross fanatics and dedicated track rats. But as good as the C5 Z is, there is still room for improvement, particularly if you are looking to tailor your car to a specific usage. Dave March was in this category. He wanted to improve his '03 Z06's handling without turning the car into a bone-jarring torture device. "My Corvette is not a dedicated race car; it's my daily driver," said March. "It goes for groceries, it goes to the post office, it goes to meetings, and it goes to the mall. That said, this is not a Cadillac or a Camry. This is a Corvette, and a Z06 at that. I bought this car to drive."

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The Pfadt Race Suspension kit comes with everything you need to turn your C5 (or C6) into a corner-burning supercar. Included are adjustable front and rear sway bars, end links, coilover shocks, spanners, and a complete set of the required hardware. Photo by Patrick Hill

March also wanted his Z to have a very low ride height. But being a tech-savvy Corvette owner (March is one of the administrators of the popular Vette-themed Web site, www.DigitalCorvettes.com), he knew that simply dropping the car without performing supporting modifications could actually impair handling instead of improving it. "I've always lowered my Corvettes," he explained. "I mean, c'mon, they just look better. And there's a good reason every track car in the world sits as close to the pavement as possible. It lowers the center of gravity and enhances aerodynamics. And did I mention it looks cool?

"Problem is," continued March, "though the GM engineers gave us some built-in ride-height adjustability, it's very limited and, at its most extreme, a trade-off at best." Anyone who has dropped a C5 more than half an inch on the stock suspension knows this is true. No doubt, the car looks absolutely killer, but the ride quality suffers, and when pushed, the suspension just doesn't work as well as it did at stock height. "After your initial excitement wears off, you'll soon feel the adverse effects. Shocks compress and the ride becomes noticeably rougher over less-than-perfect roads." March summarized it nicely, saying, "Hit a pothole or unexpected dip in the road, and that reduced spring tension makes the car feel like a Barnum and Bailey clown car. It gets really bouncy.

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Lovell began the installation by removing the stock shocks. Note that the front sway bar has already been given the heave-ho.

"Add to that the technical ramifications of the resultant suspension-geometry change, [and] it quickly becomes apparent that there is a price that comes with that meaner stance. If you want a drop of more than a half-inch or so, and you want improved handling, you're gonna need to do more than twist an adjustment bolt," he concluded.

Being a hardcore Corvette enthusiast, March is as addicted to making performance modifications as the rest of us. "As most Corvette owners know, the endless customization and personalization possibilities are much of the fun of ownership," he said. "Whether for comfort, performance or visual impact, there are thousands of catalog pages filled with every choice imaginable. But it's rare for a product to hit all three points." He's right, of course, and when it comes to suspension, March's words are particularly poignant.

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The lower ball joint should be popped loose on both sides to remove any pre-load from the leaf spring. The spring can then be removed from its perch and set aside.

Perhaps it is because the car is so very good in stock form that there are limited aftermarket options for C5 suspension components. Pfadt Race Engineering (pronounced "faht") is one company pioneering suspension products specifically designed and engineered for serious performance. That their components allow the user to adjust the ride height is just a bonus.

Pfadt Race Engineering proprietor Aaron Pfadt tells us that sway bars are the easiest way to perfect the handling of your car without sacrificing ride quality. Sway bars (anti-sway bars, actually) serve two primary functions: They reduce body roll towards the outside of the turn, and they are a means by which to tune the car's understeer behavior. The theory involved is complex to the point that books could be (and have been) written on the topic. Suffice it to say that stiffer sway bars will allow your car to corner with a flatter attitude without causing the ride degradation associated with a stiffer spring package.

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The stock Sachs shocks (left) perform remarkably well for what they are-a stock piece designed to balance performance, comfort, longevity, and cost. The Pfadt coilovers feature standard 2.25-inch diameter springs, fully rebuildable mono-tube construction, and an adjustable body length that maximizes ride-height adjustability.

"We've designed our bars to be adjustable so you can tune your handling. Our C5 sway bars are designed to bolt in for easy installation and set up to reduce your car's tendency to push in the turns," he explains. Another advantage of the Pfadt bars over stock is their lower mass. "Our bars are significantly lighter than stock and many aftermarket bars. For example, our front sway bar weighs 9.5 pounds. That is 4 pounds lighter than stock." Pfadt's "standard" sway bars measure 32mm diameter front and 26mm rear.

Coilover shocks are often thought of as hardcore race pieces. Coilovers are so named because they use a coil spring retained on a threaded shock body to support the car, eliminating the transverse leaf spring. While it is true that they are widely used on race cars of all genres, there is no reason coilovers cannot be used successfully on a dual-purpose track/street car.

Pfadt is quick to point out the coilover's virtues. "Our coilovers are engineered for exceptional street driving and track performance. Unlike some, Pfadt coilovers allow the ride height to be adjusted separately from spring pre-load. This means that ride height can be set wherever the owner desires, without turning the car's ride into a punishing experience." Pfadt coilovers also feature a compression-and-rebound-dampening adjustment that can be tuned with the shocks on the car. Additionally, the shocks are a mono-tube design for simplicity and durability, and they are fully rebuildable.

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No modifications to the car are required, as the Pfadt coilovers drop right in place.

Suspension modification can be incredibly rewarding or incredibly frustrating, depending on your experience in tuning the final package. For the install of the Pfadt package, March turned to Anti-Venom in Seffner, Florida. Anti-Venom owner Greg Lovell has 17 years of Corvette-suspension experience, which made him well-suited to the task at hand.

Lovell has installed many Corvette-suspension upgrades over the years, but he was especially impressed with the Pfadt parts. "[They] fit perfectly and were very nicely finished in both their plating and anodizing. The install was easy and went really quick. It did take some adjustment time on the alignment rack, as there are so many adjustments possible. They are truly first-class products. I highly recommend them."

Lovell graciously invited us to Anti-Venom to photograph the install of the Pfadt system. Look for our follow-up article next month, as we will get into the specific setup and have some track numbers for a stock-versus-Pfadt comparison.

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A suspension system is only as good as the setup and alignment it is given. Lovell spent considerable time perfecting the corner weights before giving the car a precision alignment designed to maximize March's intended usage. Tune in next month, when we will dive into the setup specs and get into the before and after numbers from our two lapping sessions at Sebring!


How To
Turning a 2003 Chevrolet Corvette Z06 into an open-track killer with Pfadt's Race Suspension coilover kit
Chris Endres Jun 25, 2007


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