Buy this rare Corvette C4 ZR-1 for its experimental active suspension
After a few years on the market, the Chevrolet Corvette C4 had started to look a little bland. Then, in 1990, the ZR-1 came out with a 5.7-liter aluminum-block V8 designed by Group Lotus with two overhead camshafts and four valves per cylinder, giving it 375 horsepower (280 kilowatts) and 370 pound-feet (502 newton-meters). It was a massive tech upgrade from the base ‘Vette and its iron-block V8, but the changes didn’t stop at the engine.
A wider rear track takes advantage of larger tires, and the ZR-1 comes standard with the regular Corvette’s FX3 / Z51 performance suspension, with adjustable shocks and sport-tuned springs to accompany an anti-strut bar. Thicker rear roll exclusive to the ZR -1. The results were commendable, with outrageous grip that took advantage of the added power, combined with reasonable manners on good pavement. However, it could have been even better.
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Step inside this rare 1990 Corvette ZR-1 active suspension prototype. Built using even more information from engineering company Lotus, the experiment used hydraulically operated shock absorbers and a sophisticated Delco computer system for the era, which firmed the suspension in the corners using lateral g-meters to counter body roll. At the same time, it could also react to bumps in the road almost instantly, smoothing out the C4’s notoriously brittle ride quality.
The system created a few problems, one of which was heat. To solve the problem, the car is equipped with cooling vents across the entire front, as well as a dedicated hydraulic fluid cooler. Durability was also a concern, thanks to the 3,000 pounds per square inch of pressure the fluid required – which was less easily reconciled. In addition, the dynamic sensors were so sensitive that they reacted to electronic interference.
General Motors reportedly spent $ 27 million on the Active Suspension program before cutting it for various reasons. On the one hand, the technology hadn’t quite caught up with theory, as accelerometers on wheels interfered with extremely sensitive suspension actuators – the isolating transducers that could have solved this problem wouldn’t arrive for a decade. And the active suspension would have added a lot of money to the cost of the ZR-1 – between $ 35,000 and $ 100,000 per car – a substantial sum when the base Corvette cost less than $ 32,000 and the ZR-1 around 60,000. $.
About a decade later, the Corvette C5 would be available with Magnetic Ride Control (the forerunner of today’s system), which solved some of the active suspension issues without adding almost as much cost. As the name suggests, the magnetorheological particles in the shock absorbers stiffen or soften depending on the application of magnetic force, making the Corvette more comfortable on rough surfaces without sacrificing poise on a twisty road. But instead of Lotus, Delphi designed the MRC, making the system a little less exotic than that of the C4 ZR-1 – who wants a “Handling by Delphi” badge on their car?
Fortunately, Chevrolet built 25 prototypes with the kit in 1990, four of which still exist. The vehicle you see here is one of those four, found on Hemmings in Miami, Florida, for $ 89,000 with 12,381 miles on the odometer. With regular C4 ZR-1s selling for around $ 50,000 in excellent condition, that original price premium extends into the 21st century, but the rarity of any flawless, low-mileage 1990 Corvette should make the suspension experimental. all the more attractive to collectors. The ad even says the vehicle runs and drives as it should, although future maintenance may be a trick.
Still, if you want to experience the absolute best performance GM had to offer in the 1990s, pull out the checkbook and book your flight to the Sunshine State.