Restoring An Original C2 Gauge Cluster
From the January, 2011 issue of Vette
By Brad Ocock
Photography by Brad Ocock
My dad hasn't split firewood in about 25 years, but he was still reluctant to give me the old axe. "That axe has been in our family for probably a hundred years," he said. "It was my great grandfather's. He gave it to my grandfather, who gave it to my father, who gave it to me. That ol' axe has split a lot of wood in its life." It looked pretty good for being used to heat several generations of homes through more than 100 winters. When I mentioned this to him, he said, "Well, we've taken pretty good care of it over the years...'course, it's had some repairs along the way. The handle has been replaced five or six times, and that's the third head that's been on it."
And so it goes with our beloved Corvettes. We can "restore a car back to original," but in truth, we're replacing the axe head and handle to one degree or another, especially when using reproduction parts. There's big a difference between buying repro (a new handle or head), and restoring the original stuff (a fresh coat of varnish for the handle, stripping the rust, and putting a fresh edge on the head). Given our druthers, we'll take restored parts originally built to GM specs over knock-off pieces almost every time.
We'd say that aside from brakes, there's nothing more important to your Corvette than the instrumentation. Gauges are there to keep track of all the things that keep your engine alive (rpm, oil pressure, and water temperature), as well as the things that keep you from walking (volts/amps and fuel level)
Gauges have two main components to them: the visual parts, and the mechanical ones. Visuals are the gauge faces themselves, the numbers, the pointers, and the bezels. Aesthetically, they fade, rust, and generally look dingy. Mechanically, components fail; pointers fall off, lubrication dries up, springs and other internal parts break, and sometimes things burn up. The only proper way to restore gauges is to take them apart until they're the same pile of parts Chevy's original supplier started with, and then restore them.
These gauges look like they've spent time under water...and they may well have: AutoInstruments did dozens of clusters from cars flooded by Hurricane Katrina salt water.
AutoInstruments in Martinsville, Virginia, has done exactly that for more than a decade. The company has developed specific processes for stripping, repairing, refinishing, and assembling Corvette gauges; refinishing the instrument-panel housings; and replating all the plastic chrome interior and exterior pieces. In most instances, AutoInstruments uses the same methods that Chevrolet's original suppliers used.
When your instruments come back, they'll be restored to OE specs and should be good for another 40 years. Because like the hickory handle and high-carbon steel head on that old axe, they just don't make 'em like they used to.
The process starts with stripping the instrument cluster down to its base components.
A lot of odometer mechanisms and parts interchange across numerous GM platforms, but Corvette instrumentation is unique.
Even the gauges are disassembled to their individual pieces, just as the OE supplier would have started with. Here, a special tool is being used to pull the needle off the gauge.
The instrument's gauge cup is typically riveted to the housing. A Dremel tool cuts the heads off to get inside the gauge. When it's put back together, new rivets will be peened over as original.
This is part of the speedometer; note the crack. New ones aren't available, so AutoInstruments has a large supply of donors.
This is another part of the speedometer mechanism. The magnetic head of the part in the previous caption sits inside this bell and spins it. The tiny wound spring returns the needle to "0 MPH." The broken piece in the previous picture, or a broken spring here, will cause an erratic or non-moving speedometer.
Tachometer mechanisms are also fragile. The wound spring on this one is broken, which will cause the needle to not move.
Fuel, water, and electric oil-pressure gauges have a tiny winding inside that moves the needle. If you hook up the gauge wrong or improperly test it, the winding will fry.
After the gauges are disassembled and evaluated, the faces get stripped. If they have rust pits, they're primed and sanded until the pits are gone. The final coat is the correct shade of black, in the correct gloss, and then new dials and numbers are screened onto the faces. (The process is proprietary, so we can't show it.)
Odometers and trip odometers all get new numbers, in the correct color and the correct font; Corvettes changed fonts and colors a few times during the mechanical-gauge years.
This isn't the Corvette speedometer, but it illustrates that every component is thoroughly scrubbed and rebuilt before the parts all go back together.
Once the gauges are reassembled, they're tested and calibrated.
Speedometers and tachometers are calibrated on special equipment. Tachometers are mechanically adjusted, while speedometers are magnetically adjusted.
The gauge housings are chromed cast metal. "They almost always clean up very well, without having to be replated," AutoInstruments owner Gentry Zentmeyer told us. "They rarely have any pitting, so they don't usually need to be rechromed." The factory paint is chemically stripped.
With the paint stripped off, the instrument housing looks naked. Whatever is "chrome" on the finished cluster-such as the gauge bezels-is masked off, then the background is painted in the correct shade of black. When the tape is removed, the panel is black and all the bezels are chrome, even though it's all one cast piece.
The unseen portion of the gauge housing (where the instruments mount), is thoroughly cleaned. This piece usually doesn't rust, and fading isn't an issue, but if it's a flood car or a particularly bad piece, it will be also stripped and painted.
Unlike almost every car in the '60s, Corvettes used glass lenses instead of plastic. Adhesive-backed foam pads were originally installed around the edge of the glass, but they've long since dried up and turned to dust. AutoInstruments polishes the glass and installs it, along with fresh bumpers.
Here's the restored instrument panel, concours-correct and ready to run. Original electric tachs set up to run points-type distributors won't work with modern electronic ignitions, but AutoInstruments can convert both electric and mechanical distributor-driven tachs for compatibility. The company can also change the redline marks for big- or small-block applications, or a different year.
Clocks have a set of breaker points, just like a distributor (shown here being spread apart). As on a distributor, when the points burn out, wear, or stick together, the clock stops working.
AutoInstruments uses a modern quartz-movement clock action to replace the original points-type.
The restored clocks are hooked up and run for 24 hours, then calibrated to ensure accuracy.
Though the instrument cluster is cast metal, there are plastic chrome parts on Corvettes; AutoInstruments restores and replates them to original specs as well. "It's real metal chrome," Zentmeyer tells us. "It will carry an electric current, just like the original pieces."
