"We could obviously build a $100,000 Corvette and blow away the Ferrari Testarossa, but I'm not sure what the point of that exercise is. That just shows that you can do it. Our goal is to do it at 25% the price." -Don Runkle 1986
The C4 was the pinnacle of GM technology when conceived, and gave rise to the modern Corvette as we know it today.
C4 poses with its successors
The c4 had some big shoes to fill considering the runaway success the C3 was for GM. The C3 raked in more than $100 million annually for the General. The GM board finally authorized a completely new model for 1983 to replace the aging C3. The C4 didn't actually go into production until 1984 model year, but 70 "engineering" cars were produced for 1983 model year.
Ideas for the C4 went rampant amount design and the engineers. Wankel rotaries were out of the question as GM had disappointing results with them during testing. The AeroVette brought promise to a mid-engined layout. Then there was looming government proposals of a "gas-guzzler" and a corporate fleet average of 19 mpg. Performance and fuel efficiency now had to be considered.
John Delorean, Chevrolet's general manager at the time, proposed downsizing the Corvette onto the Camaro/Firebird F-body platform to cut costs. Thankfully, Chief Studio 3 designer Jerry Palmer and the head of Corvette engineering Dave McLellan, shut that idea down quick. Delorean seemed to more profit hungry than actually improving on the Corvette.
Zora Duntov always advocated that the Corvette be mid-engined and a car that he could "proudly drive in Europe." Duntov retired in 1975, and McLellan didn't care much for that malarky. The Corvette is an American car, for American roads and drivers. He stuck to the front engine, rear wheel drive setup.
Porsche created their own Corvette anyways. Corvette stylist Tony Lapine left GM to work for Porsche in 1969. Lapine was the design chief to the front-engined, rear wheel drive 928. Porsche is European and not mid-engined, How about them apples Zora, jk.
Now came the time for McLellan to set real targets for the '83 Corvette to hit: It had to be the best handling sports car in the world, the suspension must remain compliant at full speed over uneven roads, must have a minimum of 16" wheel (Palmer's request for styling purposes), a minimum ground clearance of 5.25 inches, and tires capable of 140-145 mph speeds while keeping crisp handling, a quiet ride, efficient water shedding, an interesting appearance, and at least a 10,000 mile tread-life with enthusiastic use.
Goodyear's VR50 Gatorbacks met all those objectives utilizing a few tricks they learned from their F1 rain tire development program. These fat tires required engineering to widen the Corvette another 2" just to fit them. Then came help from good ole' Colin Chapman.
Yeah, Corvette engineers stole the backbone engineering chassis structure design that Chapman first pioneered in his Elan model. This gave the C4 better structural rigidness and they widened enough to cram in the drive shaft, exhaust, catalytic converter, plumbing, and wiring. This also allowed them to lower the seating floor 2" to the bottom of the chassis while simultaneously increasing headroom and lowering the roof line an extra inch. The lowered roof line, decreased frontal area which decreased drag, and improved fuel economy. Thanks Colin Chapman!
The C4 styling hails from John Cafaro...the youngest designer in Studio 3. Cafero took elements from a Jaguar XK-E (the clam shell hood) and the wrap-around split seam from Ferrari's 308GTB.
Presto!
Palmer saw potential in this clamshell hood design. He wanted to make the engine and mechanical parts all seem integrated. McLellan was on board with this and so both staffs coordinated engine castings, suspension pieces, spark plug wires, and so far as color coordinate pieces to ad visual impact.
ZR-1 engine bay, but nonetheless...gorgeous.
Charles Toner fine tuned the C4's shape at wind tunnel speeds up to 140 mph. His prognosis...needs more cowbell.
But Seriously, he made the call to add fender gills to the C4 in order to vent the air pressure build-up under the hood that could potential pop the thing open if left unchecked.
Then came the affectionately called "breadbox" design. It was created to pre-empt a government mandate for passenger safety...which never happened. What does the Corvette team do at this point? Meh, just leave it. It's too late in the game to change it now.
Now to the nitty-gritty. Engineers replaced all four brakes with lighter aluminum iron ones, yielding a 70 pound savings between all four corners. The suspension was fine-tuned to touch 1.0G of lateral acceleration. The entire C4 frame weighed just 351 pounds and was rigid enough to allow a removable roof center section, ain't nobody got time for T-tops.
Traversely mounted leaf springs saddled the car...which is awesome. These springs were made of fiberglass to avoid eventual sag and the setup allowed them to work as ant-sway bars. This allowed engineers to drastically reduce the width of the C4's traditional sway bars.
C4 under wraps:
Time was running out and engineering wasn't fully done with the C4 for it's 1983 introduction. Do they release the car as is or delay it to make it perfect? The GM board made the call to wait it out. Finally, production fired up on January 3, 1983 with VIN numbers identifying it as a 1984 car. There are reports that 11 of those cars actually had legitimate 1983 VINS from the assembly line...but who really knows? maybe Big Foot? Find him and let me know.
The C4's were monsters on the track.
They were banned from SCCA competition at the end of its 1987 season because they C4's smoked the competion in the Showroom Stock series. Covette had ABS brakes which allowed the C4 to go racing speeds in the rain, whereas the competition (ahem...Porsche 944s) were spinning all over the track. The real fun happened when it was C4 vs. C4.
In 1984, the C4's stunned the racing world. They won 19 races in 19 starts. For 4 years straight, they took every race in the SCCA series, be it the Playboy Challenge, Showroom Stock Gran Touring, or the Escort GT Endurance Series.
1986 Z51 equipped cars can sprint to 60 in 5.8 seconds, topping out at 154 mph.
1987 bumped horsepower up to 240.
1988 added a less restrictive exhaust, hp stands at 245.
1988 brought on the 35th anniversary coupes
1990 Enter The ZR-1
"Some people at Chevrolet don't think the ZR-1 would generate the additional volume that would be worth the investment. My position is that this project has nothing to do with volume. This is a different thing. This is to get the Corvette to be the unquestionable leader." - Don Runkle
This was the end result of Lotus and Chevrolet collaborating together. It had the LT5 V8 with dual overhead cams, 4 valves per cylinder and pushed 375 HP. It took 18 months of development and at 2:30 a.m. on May 1, 1986, in Norwich, New England...engineers at Lotus fired up the very first LT5. After running it for 30 minutes, they turned off and uncorked the champagne to celebrate. The LT5 was Chevrolet's first new V8 in 21 years, since the Mark IV in 1965. In 1993, that power jumped to 400 HP, capable of running 0-60 in 4.2 seconds. It never really sold in high numbers...but that wasn't the point, now was it.
You eventually had the emergence of the twin turbo Callaway Corvettes which gave the ZR-1's a run for its money.
1992 had some styling revisions inside and out:
and some Pace car replicas in 1995:
1994 saw a revision to the LT4's output to 330 HP.
As a final farewell, 1996 brought the Grand Sport Package Z16. Only 1,000 of them were made.
The C4 lived for 13 years, selling a total of 368.180 units, earning GM nearly $100 million in profit throughout its life time. Cars come and go, but the Corvette is hear to stay...the C7 stands testament to that.
Credits to vetteweb.com, corvettefever.com, MotorTrend, corvettes.nl, and Corvette fifty years by Randy Leffingwell
The C4 , The Car that Defined A Generation