The fourth generation Corvette was a radical departure from General Motors early Corvette engineering. It eliminated a perimeter frame to support the suspension and driveline. Two front frame rails integrated into the first ever Corvette uni-body construction. This made for an interesting driveline mounting installation. The front suspension subframe was bolted to the frame rails while providing engine mounting points. The lack of a transmission crossmember added another twist, with a torque arm supporting the transmission and connecting it directly to the differential. The differential was mounted with two large bushings at the outer uni-body rear frame area. Rear vehicle weight was supported by a transverse spring that bolted directly to the differential rear cover.
While plastic certainly has its merits in our modern society, it can be problematic when it is used extensively in automotive interiors. Temperature extremes, excessively bumpy roads, and improper removal/reinstallation are the biggest factors that can cause annoying interior component squeaks. 1984-1989 Corvettes are arguably the worst affected, with later C4s, C5s, and C6s being less susceptible to squeaks and rattles barring improper removal and/or reinstallation techniques. (more…)
Is your C4 plagued by body flex when you remove the top? This is a common complaint from most C4 owners. Cornering can feel rather uncomfortable with the top removed since the top provides a substantial amount of rigidity to the chassis. Unkempt roadways also cause problems that will eventually lead to squeaks and rattles.
The top is an integral component that helps to stiffen the chassis. When the top is removed the frame no longer is reinforced because the only frame member is below the doors. The door striker is the only other component that could be considered a source of reinforcement, but being such a small item, the support it offers is negligible.
Unfortunately, this lack of support leads to frame and body flexing which translates to ineffective cornering. It also begins to weaken the chassis as a unit. This became very evident in late 1986 when convertibles were introduced. As a result, all C4 convertibles were equipped with an underbody “X” brace. (more…)
By Chris Petris
Exhaust Gas Recirculation (EGR) came about in 1975 when catalytic converters were introduced. The inert exhaust gas was used to quell the increased heat in the engine’s cylinders from the lean fuel mixtures required to keep the catalytic converters from melting down. EGR systems also helped eliminate spark knock from the increased combustion chamber temperatures. The feds were also pushing for a reduction of NOx nitrogen oxide emissions to reduce ground level ozone formation. The EGR system was an asset in many ways during the early years of emission control. As engine controls and development advanced, EGR has become obsolete for the majority of engine manufacturers. Unfortunately, there are many Corvettes on the road with EGR systems failing. (more…)
As we covered in an earlier post (“Why Cut Up a C4 Corvette?“), for the last few years, we had been discussing the possibilities of using a donor C4 for seminar and display purposes.
We knew that many owners had plenty of questions on how the C4′s were put together. Why not dissect one for science? Wrecked, salvaged and abandoned project C4s were for sale at almost every Corvette swap meet. Corvette Central’s 1988 Cutaway was found at Corvettes at Carlisle a few years ago. In cooperation with Chris Petris of Petris Enterprises in Scottsboro, AL, the C4 Cutaway Corvette became a reality, and has been making appearances at Corvette related events over the past two years.
We’ve assembled a collection of videos, hosted by Mr. Petris, covering a wide variety of common C4 ailments and remedies, troubleshooting, maintenance tips and more. Click here to access the YouTube directory page for the C4 Cutaway Corvette videos.
Enjoy and share with your fellow C4 Corvette owners.