Also added as standard equipment in 1986 for additional protection from thieves was VATS (Vehicle Anti-Theft System), a simple yet effective feature designed to augment the existing burglar alarm. A small pellet with a specific electrical resistance was imbedded in the ignition key, and it had to be read by a hidden electronic "decoder" box before the engine could be started. Use the wrong key or try and start the vehicle by other means and the decoder would shut down the starter relay and fuel pump for at least two minutes before allowing another try.
VATS proved itself effective at greatly reducing drive-away theft. Indeed, figures later compiled by the Automobile Club of Michigan would show that while the theft rate for 1984 Corvettes and 1985 Corvettes was better than seven percent, the so-called "pass-key" system reduced it to less than one percent for 1986 models -- and to near zero for 1987 Corvettes and 1988 Corvettes. It was enough to prompt the Michigan AAA and other insurers to reduce their comprehensive premium rates for Corvettes so equipped by 20-25 percent.
Other changes for the 1986 Corvette were relatively minor. A switch from cast-iron to aluminum cylinder heads plus careful weight-paring elsewhere took some 125 pounds off curb weight, making it the first Corvette in about 20 years to weigh in at less than 3,000 pounds. However, Chevy made the new heads a little too thin, and they had to be thickened again when durability testing revealed that cracks could occur around the head attachment bosses under high engine loads.
Though delayed until about the middle of the model year, the new heads were worth waiting for, incorporating centrally located copper-core spark plugs for better combustion, plus larger intake ports and sintered-metal valve seats. The exhaust system was also revised, taking on triple catalytic converters. For all this, though, output of the L98 engine was unchanged.
Elsewhere on the car, a center high-mounted stoplamp was added, per federal regulations, and wheels were given raised hub emblems and a bright brushed finish. Fuel capacity on automatic cars shriveled by two gallons to 18. LCD instruments were re-angled to aid daytime legibility (which remained difficult all the same), and the cluster now contained an upshift indicator light that was there to help drivers achieve maximum mileage by signaling when to shift gears -- it was there to help keep the car's EPA mileage figures above the gas-guzzler level. (Oddly, the indicator light also came with the automatic transmission.) Standard tires were changed to P245/VR5016s; the Z51 package continued with P255s.
Chevrolet stated that the C4 had been designed with a topless model in mind, so the transformation from coupe to convertible was straightforward. With an eye to preserving torsional stiffness in the absence of a fixed roof, reinforcement was applied to the frame crossmember ahead of the engine; larger K-shape braces were used to connect the under-engine member to the frame rails; and X-braces were added to tie door-hinge pillars to the rear chassis torque boxes. Cowl structure, including the steering column, its mounts, and the dashboard-mounting beam, were all strengthened, as was the front torque box.
A crossbeam was added atop the rear torque box, and the steel riser behind the seats became a sturdier, double-wall affair. A center stoplamp was neatly integrated into the top of the back panel.
The result was a new drop-top Corvette that weighed only around 50 pounds more than the coupe and actually proved stiffer. It had a stiffer price as well -- just over $5,000 more than the already costly coupe. Unfortunately for Chevrolet, the ragtop's revival didn't do much for 1986 model-year sales, which slipped to 34,937, of which just 7,264 were convertibles.
Learn about other Corvettes in this generation:
| 1984 Corvette||1985 Corvette||1986 Corvette|
|1987 Corvette||1988 Corvette||1989 Corvette|
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