Chassis History, Pt 5: Dave Hill Strikes Again! Delivers evolutionary, but superior C6

Dave Hill’s 2006 Z06 stunned everyone with its stiffer than stock aluminum frame.

Dateline: 1.17.20 – Graphics by K. Scott Teeters, Images from GM archives: Corvette fans have been frustrated for years with Chevrolet’s evolutionary Corvettes. The “pie-in-the-sky” mid-engine Corvette has been around since the 1960s and anything less was evolutionary. The pending C8 aside, the C5 was the most revolutionary Corvette; because of the hydroformed steel perimeter frame, center backbone, all-aluminum LS1 fuel-injected engine, and transaxle. The C5 was the most solid Corvette ever offered and allowed engineers to vastly improve the basic suspension, the Z51, and the Z06. The racing C5-R won its class at Daytona in 2001 and 2003; won its class at Sebring in 2002, 2003, and 2004, and won its class at Le Mans in 2001, 2002, and 2004. This never would have happened without the superior basic C5 chassis. Dave Hill’s team got the C5’s chassis design so right that by 1999 they determined that a C6 needed to be started.

Whereas the C5 structure was revolutionary, the C6 was evolutionary. While the C6 chassis is different from the C5, it is essentially the same hydroformed steel perimeter frame with a center backbone, with the engine, torque tube, and transaxle all as stress members of the overall structure.

Photo: GM Archives

Let’s start with the basic C6 chassis. The chassis has a 1.2-inch longer wheelbase of 105.7-inches, but the overall length is 5.1-inches shorter than the C5 chassis. To achieve this, engineers shortened the frame rails 2.4-inches and changed the tube-formed front bumper beam to a unit made with two channels welded together to save 2/3s of an inch. The shorter frame with less overhang on the body achieved a total of 5.1-inches of length on the C6, over that of the C5. The shorter frame also increased the torsional stiffness. And to reduce squeaks, rattles, and vibrations, high-strength steel braces were added to the frame to improve structural rigidity.

Weight savings were picked up by using extruded aluminum beams in the interior instead of the cast aluminum beams from the C5. The instrument panel has additional brackets for the beam under the dashboard. Side-impact beams were made of aluminum and saved 4.5-pounds, plus the doors do not have traditional latch and lock mechanisms. Aluminum braces were used through the structure to improve crash performance. The front skid-bar in front of the radiator is also aluminum. An aluminum panel that saved 1-pound and increased stiffness replaced the steel driveline panel under the driveline torque tube. To increase upper rigidity, the windshield frame has extra gussets. And the trunk uses lightweight plastic braces. Corvette systems engineer Ed Moss said, “We are making it (the C6) smaller, lighter, but stiffer.”

The issue of stiffness in high-powered sports cars with wide tires cannot be under-estimated. Increased grip, torque, and horsepower will put tremendous added stress to a performance car’s structure. Imagine what would happen if a LT5 engine and big tires were applied to a stock C1 chassis. The C5 1999-2000 Corvette Hardtop, with its bolted and bonded hardtop increased the overall structural stiffness by 12-percent, enough to make it an excellent base to build the Z06 upon. The basic C6 platform offered a significant improvement in stiffness that made it an excellent platform to build the Grand Sport that used Z06 suspension parts and wide tires. Without any increase in power, the Grand Sport was a better Corvette. Stiffness matters.

Photo: GM Archives

While the C6’s suspension is similar to the C5’s, there are no carryover parts. The basic design of the short-long A-arms, transverse composite leaf springs independent suspension is the same. The control arms, springs, dampers, bushing, sway bars, and steering gear are all completely redesigned. New hub knuckles and dampers allow for greater suspension travel thanks to improved clearance. One issue with C5s was road noise and twitchiness on rough roads. To improve handling and ride, steering geometry and the progressive rates of the composite springs were improved.

Like the C5 the C6 offered customers three levels of suspension performance. Chevrolet calls the basic C6 suspension, “tuned for balance, ride comfort, and precise handling.” This is for the customer that wants a Corvette because they like “driving a Vette” with 400-horsepower on tap when they want a brief thrill, but aren’t interested in exploring the limits of tire grip.

Photo: GM Archives

The F55 Magnetic Selective Ride Control was a $1,695 option with some amazing technology. Magnetorheological dampers use metal-infused fluid that controls the viscosity of the fluid with a magnetic field created by an electromagnet. This semi-active suspension adjusts the fluid via a computed to adjust damping rates based on road surfaces down to the millisecond. The active handling and antilock systems were smarter and less intrusive.

And for the enthusiast that doesn’t want to go for the serious big gun Z06, but wants the most from their base model Corvette, there was the $1,495 Z51 Performance Package. The F51 option has been around since 1984 with a starting price of $600 with prices fluctuating through to 1990. Then from 1991 to 1995 Chevrolet offered the $2,045 Z07 Adjustable Suspension Package. The Z51 option was back in 1996 but consisted only of stiffer springs and stabilizer bars for $350 from 1996 to 2003, then $395 in 2003 and 2004.

Photo: GM Archives

The Z51 was part of the C6 lineup from 2005 to 2009 and was a whole different animal. Costing $1,495 in 2005, then $1,695 from 2006 to 2009, the Z51 package was the most comprehensive Z51 package ever offered, consisting of; higher rate springs and shocks; larger sway bars; larger cross-drilled rotors – 13.5-inch diameter on the front and larger 13-inch diameter on the rear; coolers for the engine oil, transmission, and power steering; higher-grip Goodyear EMT tires; revised gear ratios for the 6-speed cars.

Photo: GM Archives

An interregnal part of the overall objective of a smaller, lighter, and stiffer C6 was the body. For the body part of the C6, designers wanted to improve the fit of the body panels and reduce weight. For the broad flat parts, such as the hood, doors, trunk lid and tonneau cover on the convertible, SMC – Sheet Molded Compound was used. This is a fiberglass mixed with resin that is compressed into a mold, with a chemical reaction and the heat from the compression curing the part. For more complex shapes, such as the front grille and the rear fascia, PRIM – Polyurethane-Material Reinforced-Reaction Injection Molding was used. The removable roof panel was made from Polycarbonate, either transparent or painted.

Photo: GM Archives

But the major breakthrough for the C6 chassis was the all-aluminum chassis for the Z06 and the ZR1. The basic chassis design is the same except that the hydroformed side rails are made of 4-mm 5745 aluminum alloy. The standard C6 steel frame thickness was 3-mm and weighs 502-pounds while the aluminum Z06 frame weighs 392-pounds; that’s 110-pounds lighter, or 22.5-percent lighter. The Z06 frame is 50-percent stronger in torsional and bending stiffness. The Metalso Metal Fabricator, in Hopkinsville, Kentucky manufactured the aluminum frames and then shipped them to the Corvette Bowling Green assembly plant. The engine cradle and fixed-roof panel are magnesium, and the floorboards were carbon fiber.

Everything tends to move upward in the world of Corvettes. When the Z06 debuted in 2006, no one imagined that the C7 base Corvette would ride on a C6 Z06-like chassis.

Scott

Corvette Chassis History, Pt 1 – C1 Chassis – HERE

Corvette Chassis History, Pt 2 – C2/C3 Chassis – HERE

Corvette Chassis History, Pt 3 – C4 Chassis – HERE

Corvette Chassis History, Pt 4 – C5 Chassis – HERE

Corvette Chassis History, Pt 6 – C7 Chassis – HERE

 


 

Corvette Chassis History, Pt.4: The C5 Chassis That Dave Hill Built

The C5 Corvette’s Momemtim Chassis took the Corvette to a whole new level and paved the way for the C5-R Corvette

Dateline: 1-16-20 – Graphics by K. Scott Teeters, Images from GM archives: Structure is everything. Lessons learned from the C5, C6, and C7 Corvettes is that the stiffer the chassis, the better the suspension can be tuned for improved handling. The C1 to C4 chassis’ were fine for their day, but compared to the modern Corvettes, they leave a lot to be desired, especially if bigger tires and more horsepower is applied. The issue of structure is not new; look at what the Greenwood brothers were doing with the chassis of their widebody IMSA Corvettes in the 1970s. The NASCAR cars of the 1970s had fortress-like cages welded to their frames; but you can’t live with structures like that for streetcars. The arrival of the C5 was a quantum leap in terms of structure.

Image: GM Archives, 1997 Corvette Brochure

Joe Spielman ran GM’s Midsize Car Division in 1992 and was responsible for forty-percent of the engineering and manufacturing of GM’s auto production. It was a bad time for GM and despite the Corvette’s iconic status; its future was in jeopardy. Spielman created the “Decision Makers” that included himself, Carlisle Davis, John Cafaro, and Dave McLellan. Three possible formats for the C5 Corvette were created. The first format was the “Momentum Architecture” that featured a stiff backbone, front-engine, rear transmission, and an evolutionary body style. The second format was the “Mid-Engine”, favored by McLellan and GM President Jack Smith. The 1990 CERV III wasn’t just a dream car, it was built with manufacturing in mind, but was going to be complex and expensive. The third format was “Stiffer and Lighter”. This would be the least expensive and was a stiffer, lighter version of the C4. Fortunately, the team went with the “Momentum Architecture”.

The problem was money. When Dave Hill took over, as Corvette chief engineer in November 1992, his 1993 development budget was just $12 million. The estimated total cost to design and develop the C5 was originally $250 million and was cut back to $150 million; GM was in financial trouble and was cutting everything. But Chevrolet general manager Jim Perkins saved the Corvette by juggling an extra $1.2 million so that Hill could build a demonstration car. Another consideration Perkins wanted to see was a “Billy Bob” no-frills concept. Hill’s demonstration Corvette would become the CERV IV, with a manual transmission. Later Hill build an automatic version called the CERV IVb. The “Billy Bob” concept wasn’t developed until 1998 and became the 1999 Hardtop, that later became the now-legendary Z06.

The CERV IV was a true stealth development car. The chassis had the backbone structure of the proposed “Momentum Architecture” plan, but was clothed in a C4 body so that Hill and his team could drive the car on public roads, as well as the Proving Grounds in Michigan and Arizona. To the public it was just another C4 Corvette. Hill’s objectives for the CERV IV were to; prove to GM’s president Jack Smith that his team could reinvent the car, as well as the building process. When Hill took people for test-drives, they said, “This is like no Corvette we ever felt!” Hill’s plan worked, he got his C5 development budget up to $241 million, and set his team to work.

Image: https://www.corvettes.nl

Hill wanted the C5 to be able to do everything as well as, or better than the C4. The C4 had a 350-mile range; Hill wanted 370 for the C5. The solution to the fuel range was a blessing because instead of one tank mounted on top of the rear of the frame, the C5 has two tank placed low on each side of the transaxle. This also helped lower the C5’s center of gravity. Hill wanted a coefficient of drag of .29, the lowest of any production car at that time, so he had to lean on designer John Carfaro.

But the piece de resistance of the C5’s new structure was its hydroformed frame. The first mass-produced automotive application of Hydroforming was for the instrument panel support beam in a 1990 Chrysler mini van. The 1997 C5 Corvette was the first mass-produced automobile to use this manufacturing technique on a major structural component. The frames of all pervious Corvettes were made from sheet steel, bent to form a box section. The box sections were then welded together to form the side rails and cross members. Hydroforming creates complex shapes that are stronger, lighter, and more rigid. After engineers designed the shape of the C5’s frame rails, sheet steel was rolled into a tube, laser-welded, and bent into the basic shape of the frame rail. The shaped tube was then placed inside a form and sealed. Water was then pumped into the tube at 7,000 psi that inflated the steel into the shape. The finished side rail was one, 13-foot long piece, instead of many boxed pieces all welded together. The crossmembers and attachment brackets, (36 pieces in total) were welded by robotic and human welders. Convertibles have 33 parts, one extra for the tonneau cover latch.

https://www.corvettes.nl

The second major structural component on the new C5 was the longitudinal center tunnel backbone. This kind of construction had then only been seen on exotic supercars and racecars. The center backbone creates the driveshaft tunnel and locks the front and rear of the frame together. The C4 designers had a long driveline support torque bar that bolted to the end of the transmission and the rear differential, whereas the designers of the C5 created an enclosed torque tube that bolted to the back of the bellhousing and the front of the transaxle, with a lightweight Metal Matrix Composite (MMC) driveshaft. The torque tube that connects the engine with the transaxle, was then bolted to the frame. Combined with the center backbone, the C5’s chassis structure is four times as stiff as the C4. This was an amazing accomplishment for a mass-produced sportscar.

With the strongest structure ever created for a Corvette, Hill’s suspension engineers were better able to design components to fine tune wheel control. Now the suspension didn’t have to compensate for a flexing structure. The selection of springs, dampers, anti-roll bars and bushings can be more accurate. The C4 suspension was very good and is today used often on street rods. The C5 went to the next level with double A-arms on all four corners of the independent suspension. The new aluminum suspension components are made using the then-new process of casting-and-forging to create lighter, stronger parts.

The C5 came with three levels of suspension. The standard FE1 was for basic driving and used specifically selected fiberglass composite leaf springs, shocks, sway bars, and bushings. The $350 optional Z51 suspension had stiffer springs, shocks, and larger-diameter sway bars. Active suspension options had been around since 1989; the new C5 offered the latest version of the F45 Selective Real Time Damping for $1,695. The C5’s basic dimensions tell us a lot. The C5 is 179.4-inches, 1.1-inches longer than the C4; 73.6-inches wide, 2.9-inches wider than the C4; 47.8-inches in height, 1.5-inches taller than the C4; 104.5-inch wheelbase, 8.3-inches longer than the C4; and 3,221-pounds, 77-pounds lighter than the C4. Wider, lighter, stiffer, with an all-aluminum engine, transaxle, and over 1,200 fewer parts, the C5 was the most revolutionary Corvette to date.Scott

Corvette Chassis History, Pt 1 – C1 Chassis – HERE

Corvette Chassis History, Pt 2 – C2/C3 Chassis – HERE

Corvette Chassis History, Pt 3 – C4 Chassis – HERE

Corvette Chassis History, Pt 4 – C5 Chassis – HERE

Corvette Chassis History, Pt 5 – C6 Chassis – HERE

Corvette Chassis History, Pt 6 – C7 Chassis – HERE

 


 

 

Corvette Chassis History, Pt. 3: The C4 Chassis That McLellan Built

After 20 years of use, the C2/C3 Corvette chassis was finally replaced with a strong, lightweight, vastly improved chassis and structure.

Dateline: 8.9.19 – Illustrations  from GM Archives, Grahics by K. Scott Teeters – The C2/C3 chassis had an amazing 20-year production run. When Dave McLellan took over as Corvette’s chief engineer in 1975, the Corvette was overdue for a redesign. The only good thing about the 1970s was that Corvettes sold very well. On January 22, 1979 McLellan received approval to start designing the C4 Corvette.

One of the C3’s endearing features was the T-top roof. The design wasn’t just for aesthetics; the T-bar connected the A-pillar windshield frame to the B-pillar frame “roll bar” and provided significant structural stiffness. The initial design of the C4 had a T-bar connecting the A and B-pillars, but with a one-piece, roof panel. It wasn’t until the first prototype was built in 1981, when Chevrolet general manager Lloyd Reuss made the decision to eliminate the T-bar to open up the cockpit. This single decision impacted the C4 design such that the biggest complaint about C4s is the tall side frame sills that make ingress and egress challenging. To compensate for the lack of the important T-bar, the side frame sills had to be made extra tall. As the years rolled by, C4s, especially the convertibles, took heat for not being as stiff as their competitors. Those two elements, plus the fact that progressive Corvettes kept getting better and better, are part of the reason why C4s are today the least desirable of all Corvettes.

McLellan’s engineers had two overriding design elements; first, they wanted a lower overall height; and second; they wanted more ground clearance. McLellan’s team started placing the big pieces in a process they called, “stacking”. Starting at the ground level, the engine had to be lower to improve forward visibility. Previous Corvettes had been two-part cars; a body bolted on to a chassis. But the C4 was a three-piece car, which included, a chassis, a birdcage, and a body. This created a more integrated body and stronger configuration.

The C4’s parameter frame was built from 18 pieces of stamped and boxed high-strength steel that included the tall side sills, the front sides, the rear sides, four crossmembers and braces. All of the pieces were put together in a jig and welded together. The birdcage section included the forward door jams, the dash crossmember, the A-pillar, the rear section of the floor pan, and the B-pillar. The completed birdcage was then welded to the parameter frame. An aluminized steel engine and front suspension cradle positioned the engines and provided mounting points for the front suspension. The rear section of the frame was aluminum and provided mounting points for the rear suspension and rear bumper.

Unlike the previous chassis’ that had the engine, transmission, and suspension simply bolted to the frame, the C4 used a steel driveline support that was bolted to the rear of the transmission and connected to the rear differential that housed the driveshaft. By doing this, all of the components became stress members of the chassis structure.

Thanks to the C4 Corvette’s unique clamshell hood, Corvette owners got to see more of their front suspension than ever. Gone were the days of heavy stamped steel upper and lower A-arms. The C4’s front A-arms and spindles were slender, computer-designed forged aluminum. The C4 suspension used composite leaf springs on the front and rear suspension. Don’t let the term “leaf spring” throw you. These are computer-engineered, high-tech, lightweight suspension parts. A composite fiberglass monoleaf spring was first used in 1981.

To download a PDF version of the 1984 Corvette brochure, CLICK HERE.

To download a PDF version of the 1984 Corvette brochure, CLICK HERE.

C4’s multi-link rear suspension eliminated the C2/C3 rear end “squat” upon hard acceleration. This setup uses upper and lower control rods that connect the wheel bearing yolks to brackets mounted to the vertical section of the of the rear of the frame. Each bearing yolk has support rods that tie it to the rear differential. Today when we look at C4 Corvettes, especially tired old examples, the frame and suspension looks somewhat crude and outdated. However, C4 suspensions are regularly harvested from salvage yards, cleaned up, and refreshed for street rods.

From the perspective of the C4 Corvette’s November 30, December 1, 1982 press debut, the car was a total “WOW!” The cover story of the March 1983 issue of Road & Track was “Corvette Spectacular!” The debut wasn’t unlike the debut of the C6 and C7 Grand Sport Corvettes, in that with virtually the same horsepower, teamed with a much better suspension (the Z06 on the C6 and C7 GS), the car is vastly improved. Automotive journalists were blown away by how tight and solid the new C4 was. But it was the skidpad performance that astounded everyone. Z51 examples had no trouble hitting 0.95g on the pad, and one Z51 with slightly wider front tires scored a 1.01g! Ferrari’s $80,000 512 Boxer could only generate 0.86g, and Richard Petty’s Grand National Stock Car scored 1.04g. The March 1983 issue of Popular Mechanics proclaimed, “1983 Corvette: Best American Car Ever!”

Bowling Green started the 1984 season early and consequently racked up the second-best ever sales season with 51,547 Corvettes sold. Media hype totally stoked Corvette fans for the Z51, such that 50.4-percent of all 1984 Corvettes were ordered with the $600 Z51 option. Then reality set in. On real roads the ride was for many unbearable, in fact, many owners of regular 1984 Corvettes weren’t happy with the ride quality. Corvette engineers acknowledged that they had “over-done-it” on the suspension.

For 1985 engineers softened the front springs by 26-percent in the front and 25-percent in the rear. Z51 springs were softened 16-percent in the front and 25-percent in the rear with larger stabilizer bars. 1985 also saw the return of a full-fledged fuel-injection system with the introduction of the L98 that had a 25-horsepower bump that made the Corvette, according to Car and Driver, “The Fastest Car In America”. It was also the beginning of a three-year romp by Corvettes in the SCCA Showroom Stock Series. Corvettes so dominated the series they were kicked out in 1988 and Porsche bought a C4 Corvette to learn why the car was so fast.

But as power started to nudge up and tires got wider, the inherent design flaw with the C4’s lack of a T-bar was more obvious, especially on the convertibles; even with a bolt-on X-brace on the bottom of the chassis that raised the ride height 10mm. Since there are so many C4 Corvettes out there that few want, unless the car is a special edition or a pace car, you can do almost anything to a C4 and never get any heat. I learned from the C4 forums that many C4 owners that are hot rodding their cars use the factory X-brace and frame torsion rods to stiffen the structure of their car. Makes sense if you are adding a lot more power and bigger tires.

The C4 had a long run of 13-years. Towards the end of McLellan’s tenure as Chief Engineer in the early 1990s, he pushed for the C5, but GM was having money trouble and was in no mood for a new Corvette. In fact, they were considering eliminating the Corvette. By September 1992, McLellan retired and the following month, Dave Hill was the new Corvette Chief Engineer. The C5 Corvette would be Hill’s to design.– Scott

Corvette Chassis History, Pt 1 – C1 Chassis – HERE

Corvette Chassis History, Pt 2 – C2/C3 Chassis – HERE

Corvette Chassis History, Pt 3 – C4 Chassis – HERE

Corvette Chassis History, Pt 4 – C5 Chassis – HERE

Corvette Chassis History, Pt 5 – C6 Chassis – HERE

Corvette Chassis History, Pt 6 – C7 Chassis – HERE


 

Corvette Chassis History Pt. 2: C2/C3 1963-1982

The C2/C3 Corvette Chassis That Zora Built

Dateline: 7.31.19 – As seen in the January 2019 issue of Vette magazine, Illustrations by K. Scott Teeters – When the 1963 Sting Ray made its public debut in September 1962, it was a total, “WOW!” And it wasn’t just the Corvette’s stunning new looks; it was the all-new chassis and suspension. By late 1959 Zora Arkus-Duntov was in charge of Corvette engineering. When Bill Mitchell’s design team started work on project XP-720 (the all-new Sting Ray), Duntov was called in to set the parameters for an all-new chassis. The completed Sting Ray looked like the sportscar from another planet and the chassis had everything except four-wheel disc brakes. Today the running chassis looks like a buggy compared to the stout aluminum, steel, and magnesium chassis’ of the C5, C6, and C7 Corvettes. But in 1963 the top-performing L84 Fuelie engine only had 360 “gross” horsepower and 352-LB/FT of torque putting power-to-the-ground with 6.70×15 bias-ply tires. That’s not much twisting on the chassis, so the chassis was more than adequate.

Even when the high-torque big-blocks arrived in 1965, for street use, the Duntov chassis could handle the job. The design didn’t start to show its limitations until the 1968 L88 racing Corvettes with wide tires started competing in long endurance races. Tony DeLorenzo once commented that after long 12 or 24-hour races, their Corvettes needed new frames. Their solution to this problem was a Logghe Brothers full welded-in roll cage. Greenwood’s wide-body Corvettes were so reinforced many asked, “Is there still a Corvette in there?” But for street use and spirited driving, the Duntov chassis served the Corvette well until 1982. Lets look at the chassis’ basics to see why it lasted so long

The genius of Duntov’s chassis was how much lower the center of gravity was. Chevrolet engineer Maurice Olley was a production car chassis and suspension expert when he designed the C1 chassis. As a racing expert, Duntov knew he had to get the center of gravity much lower. The C1’s chassis had a parameter frame with x-bracing in the center for rigidity. The car’s occupants sat on top of the frame. Everything measured from there; the cowl height, engine height, and everything else.

Duntov’s design eliminated the x-brace so that the occupants could be placed down inside the frame, dramatically lowering every data point from there. For rigidity the new frame had five crossmembers. Duntov then mounted the engine and transmission as low and as far back as possible and routed the exhaust pipes through holes in the second frame crossmember. The passenger compartment was pushed back as far as possible and the spare tire was mounted below the back of the frame and under the fuel tank.

The lowering of the engine/transmission and passenger compartment lowered the center-of-gravity from 19.8-inches to 16.5-inches. Moving major components as far back as possible in the shorter 98-inch wheelbase created a front/rear weight distribution of 47/53-percent. The engine centerline was offset 1-inch towards the passenger side because passenger footwell requirements were less than the driver’s. The extra offset reduced the transmission tunnel width and allowed the crankshaft and rear axle pinion to be on the same centerline. Ground clearance was just five-inches.

The build of the frame used boxed longitudinal sides with five crossmembers that were designed to suit the needs of styling. The new frame actually received computer analysis to determine the thickness needed for the parameters of the overall car. The front crossmember was welded to the sides and not bolted-on like the C1 chassis. The new frame with mounting brackets weighed 260-pounds, the same as the C1’s frame, but torsion rigidity increased from 1,587 lb/ft to 2,374 lb/ft per degree.

The C2/C3 suspension was a parts-bin marvel, although it didn’t seem that way. Duntov wanted an independent rear suspension and was immediately told, “No! It’s too expensive.” To get around this, Duntov used almost 60 full-size passenger car front suspension parts, including pressed-steel wishbones and ball-jointed spindles, and just rearranged them. The parts had already been engineered and proven, thus saving production cost. With a 9-degree slope, the wishbones gave an anti-dive reaction upon heavy braking. Then the inner pivot points were lowered to raise the roll-center to 3.25-inches above the ground. A recirculating-ball steering unit was placed behind the suspension and used a hydraulic damper to reduce kickback. All of these changes were very apparent when combined with the right shocks and anti-roll bars when the cars were first driven and tested. The money saved was more than what went into the rear suspension.

The independent rear suspension started with the differential pumpkin bolted to the 4th crossmember with the driveshaft as a device to control forward thrust from the wheels. Axle half-shafts with universal joints are on each side of the differential. Steel box-section control-arms carry the outer half-shafts and attach to the rear frame kickup assembly. Shims at the forward pivot-points are used to adjust toe-in alignment. Strut rods attach to the strut-rod bracket bolted below the differential and connect to the rear spindle support on the control-arms. The nine-leaf transverse spring with polyethylene liners between each leaf to reduce noise, mounts under the differential and is sprung against the rear portion of the control arm with long bolts. Duntov’s proposal to use a transverse leaf spring was not well received by Chevrolet chief engineer, Harry Barr, but no one could come up with a better plan.

For its time, Duntov’s chassis worked very well, but I’m sure that no one imagined it would be used for 20 years. The design proved to be easy to update. Disc brakes were in development when the Sting Ray came out and arrived on the 1965 model. When the new Mark IV became available in 1965 the suspension got stiffer front springs and larger diameter front and rear stabilizer bars. The new chassis was totally adaptable and could be made near-battle-ready with suspension component changes. During the 20-years of Duntov’s chassis, Racer Kits included; the 1963 Z06, 1967-1969 L88, 1970-1972 LT-1 small-block ZR1, and the 1971 big-block ZR-2. And from 1974-1982 there was the FE7 Gymkhana Suspension for spirited street driving. On the street, Duntov’s chassis could easily handle the 327 Fuelie to the LS6 454.

In the ‘70s chassis changes were made to conform to tightening regulations. Starting in 1973 the chassis had to handle the new 5-mph crash bumpers and steel side-door guard beams. In 1975 catalytic converters helped reduce emissions, but cloaked engines. A steel underbelly had to added to the chassis as a heat shield against the very hot converters. 1980 saw a big weight reduction from 3,503-pounds to 3,336-pounds thanks to an aluminum differential, lighter roof panels, thinner material on the hood and doors, and the use of the aluminum L84 intake manifold on the standard engine. The following year, a fiberglass-composite rear leaf spring helped shed 29-pounds. Early ‘80s Corvettes don’t get much respect because their restricted engines, but their drivetrain and suspension was as good as ever. An early ‘80s Corvette with a classic SBC crate engine would make for a stout performer.

Yes, Duntov’s chassis looks crude by today’s standards. But Corvette development is always empirical. If it weren’t for the C2/C3 chassis, there never would have been a C4 chassis, and so it goes. – Scott

Corvette Chassis History, Pt 1 – C1 Chassis – HERE

Corvette Chassis History, Pt 2 – C2/C3 Chassis – HERE

Corvette Chassis History, Pt 3 – C4 Chassis – HERE

Corvette Chassis History, Pt 4 – C5 Chassis – HERE

Corvette Chassis History, Pt 5 – C6 Chassis – HERE

Corvette Chassis History, Pt 6 – C7 Chassis – HERE


 

Dude! Where’s the Rest of My C6 2008 Corvette?!?!

Dateline: 12.8.11

A TOTALLY EXPOSED 2008 Corvette Chassis, Engine, & Suspension

(Check out the slide show at the bottom of this post.)

To check out the eBay listing, click the above image.

Okay, I’ll admit it, I’m a chassis freak. I love looking at the fiberglass shapes of all Corvettes, to me they are never boring or dull. But I have an equal passion for what’s going on UNDER all the pretty fiberglass and carbon fiber. What holds the car together? What do the suspension parts look like? What makes the car handle the way it does? Without the right stuff under the body, you could end up with a car that looks like a million bucks draped over a VW Beetle or Pontiac Fiero platform. No matter how cool-looking most of those kit cars are, once you fire on up and drive away, if it’s a Beetle or Fiero underneath, THAT’S ALL YOU GET.

We have a large eBay store and the other day while looking up something on eBay, I happened upon another bare, naked Corvette chassis. This one is a 2008 with the LS3 engine, air flow meter, six-speed manual transmission, shifter, transmission harness, complete suspension, brake system, wheels, tires, wiring harness, exhaust system, body harness, emergency brakes, fuel tanks, and more. Continue reading “Dude! Where’s the Rest of My C6 2008 Corvette?!?!”

Vette Videos: How Hi-Tech Z06 & ZR1 Aluminum Frames Are Made

Dateline: 10.17.11

What was once considered pie-in-the-sky and experimental, is now regular production!

To see the much larger version of the Z06/ZR1 chassis, just click the above image

Aluminum has been the automotive industry’s magic material for over 60 years. Corvette engineers have been thinking about an all-aluminum engine and drive train for the Vette since the 1957 Q-Corvette proposal. While it took until 1997 to get there, the engineering department seeded aluminum parts whenever they could.

Nearly 40 years ago, Corvette engineering decided to explore an all-aluminum Corvette. Everything but the tires, plastics, wiring, glass, and other essentials was to be aluminum. Working with Reynolds Aluminum Company, the experimental XP-895 was debuted to the automotive press in 1973. The chassis design was the same as the experimental 2-rotor Corvette, but power was supplied by a 400-CID small-block engine. The completed aluminum car weighed 400-pounds less than the steel bodied XP-892 Wankel-powered experimental. While the styling of the aluminum “Corvette” was interesting, the only design element that connected it to anything Corvette was the aft portion of the roof, from the B-pillar back. Overall, it did not scream “CORVETTE!” but then again, the all-aluminum car wasn’t supposed to be a styling exercise for the C4 Corvette, it was a feasibility study.

The B-pillar roof section of the car looks like a Corvette, but not much else.

Fast forward to the 2006 Z06 and its aluminum chassis. One of the biggest challenges with an aluminum chassis is the strength of materials issue. Lightweight aluminum is soft, so there were interesting shape and construction problems that had to be worked out to mass-produce such a chassis. While it is true that the Z06 wasn’t the first car to use an aluminum chassis (many hand-made exotic cars had aluminum chassis) the Z06 was the first “mass produced” car to have an all-aluminum chassis, engine, and suspension. The net result to that the 2012 Z06 weighs about the same as a C2 mid-year Corvette… with nearly double the horsepower as a base model C2. That’s progress for you. Continue reading “Vette Videos: How Hi-Tech Z06 & ZR1 Aluminum Frames Are Made”

Corvette Odd-Ball: SHOCKING! Naked C1 Fuelie Corvette!

Dateline: 7.18.11
An Expose-look under the pretty fiberglass of a C1 Fuelie Corvette!

Now here’s something you don’t see every day. A C1 Corvette without a body and interior. Just the engine, drive train, suspension, wheels, tires, and the steering wheel. And not just any C1 Corvette, a Fuelie Corvette!

Up front I must apologize because when I was at the April 2011 Strictly Corvettes and American Muscle Cars Show at the Atlantic City Convention Center, I was also a vendor and had little time to get away from my booth. So I kind of zoomed through and took pictures of what looked interesting. The chassis-only display really caught my eye. You just don’t see this every day. I did the same thing with Kevin McKay’s drivable 1969 427 L-88 drivable chassis-only, Corvette. (see links below) Continue reading “Corvette Odd-Ball: SHOCKING! Naked C1 Fuelie Corvette!”

Dude! Where’s the Rest of My C5 2000 Corvette?!?!?

Dateline: 7.8.11:
Here’s What’s Under All the Pretty Fiberglass of a Typical 1997 – 2004 C5 Corvette

Click the images to see a larger version.

Now here’s something you don’t see every day. While researching my next Illustrated Corvette Series story for VETTE Magazine about the 1996 LT4 Corvette engine, I happened upon this interesting item for sale on eBay by F•Parts. The listing is not an auction, it’s a Buy Now or Make Offer offer.

If you’re looking for a complete engine, drivetrain, suspension, chassis, wheels, brakes, and tires for some kind of street rod project, for just $5,999.00 or better, you can be off to a good start. Continue reading “Dude! Where’s the Rest of My C5 2000 Corvette?!?!?”

Kevin Mackay’s Drivable, See-Thru, ’69 L-88 Corvette

Drivable Corvette Art

I consider Kevin Mackay to be a “Corvette artist.” Some of us use paint, markers, pen & ink, etc. You know, “artsey” stuff. Some artists work in other mediums – such as metal and fiberglass. Kevin Mackay’s “Corvette Repair” doesn’t just perform world-class restoration work on classic C1, C2, and C3 Corvette race cars and regular Corvettes, Kevin is also a mechanical, educational artist.

It’s always a pleasure to see Kevin at the shows. Last weekend we were vendors at the Strictly Corvettes and American Muscle Cars Show in Atlantic City. When you love Vettes, what’s there to not like about a Corvette show? We saw lots of smiles and had many interesting conversations. Kevin Mackay was on hand for the third year in a row with a delightful stable of customer cars, as well as several of his beauties. Continue reading “Kevin Mackay’s Drivable, See-Thru, ’69 L-88 Corvette”

A Naked Corvette? – Driveable Chassis ’67 Big-Block Corvette

67 Big Block Corvette Chassis
67 Big Block Corvette Chassis

Let’s Play, “Corvette Oddball!”
Quirky Vette Factoids

by K. Scott Teeters

Question:
Do you really need a body for your Corvette?

Answer: Not really, but it’s nice to have one.

A Naked Corvette…

This car has been seen at many  Corvette shows. over the last few years. It’s just too quirky to not share. The car is a fully functional ’67 big-block Corvette… with no body – just the fully running chassis. It must be a BLAST to drive! Continue reading “A Naked Corvette? – Driveable Chassis ’67 Big-Block Corvette”

Vette Polls: Should the C6 ZR1 Corvette Chassis be the Basic C7 Chassis?

Cast Your C7 Corvette Vote!

Should the current ZR1 all-aluminum chassis be the foundation for the base model C7 Corvette?

View Results

Loading ... Loading ...

ZR1 Corvette Chassis Display:
Corvette Chassis Engineering At Its Best!

2010 Corvette as seen at the Corvettes at Carlisle GM Engineers' Tent
The New ZR1 Corvette as seen at the Corvettes at Carlisle GM Engineers' Tent

An off-the-showroom-floor ‘09 or ‘10 ZR1 Corvette could walk away from most of the Corvette racers on display by 20 to 70 mph… with the air conditioner and stereo on!

I don’t believe that it’s possible to look at an ‘09 or ‘10 ZR1 Corvette and yawn. Continue reading “Vette Polls: Should the C6 ZR1 Corvette Chassis be the Basic C7 Chassis?”