You wouldn’t think that 12 measly volts would cause more than a spark. You’ve stuck your tongue to a nine-volt battery as a kid and no big deal, right? But to think that 12 volts can take down a whole car?
There are portable welding packs that run on car batteries, which means that if crossing up connections and grounding out a power wire can turn metal into a molten puddle, then electrical fires are entirely possible. Never mind the annoying flickering dash lights or the signal light that you just can’t get working no matter how many different bulbs you try.
This can be extra challenging on a car such as a vintage Corvette — which is made of fibreglass and not metal — because the body can’t act as a grounding source.
It’s critical that wiring is brought up to speed even if you’re not doing a complete restoration.
Over time, wiring corrodes, the outer casings become brittle and crack, and rodents can also invade. Combine this with moisture from being outdoors, extreme hot and cold cycling and constant vibrations that cause wire chaffing and it all adds up to trouble.
For safety sake, total replacement is a wise choice.
Just as important as sourcing the correct wiring harnesses is finding someone who actually knows something about how it all works, if only to add extra insurance that everything is going back together correctly.
Our wiring pro advised adding sheathing anywhere that the wires’ casings are exposed and especially where wiring is sandwiched between carpet/underlay and the car body, even though the factory might not have had such sheathing.
Some wiring harnesses might not be available, which means they’ll likely have to be remade. In the case of the meaty under-dash main harness for the Corvette, it might be more practical to clean it (it will be the dirtiest and dustiest harness in the car), inspect and fix/replace any suspect wiring/connections.
Safety would be the first reason to replace 50-year-old factory wiring, and the other would be that we’re not putting grungy old wiring back into what is basically a brand-new car.
Remember, the wiring is only designed to support what the car came with.
Adding aftermarket goodies such as alarms and audio systems, or updating to fuel injection from carburetion need to be properly planned and integrated. Plugging a 1,500-watt stereo into the fuse labelled ‘headlights’ (or any lights for that matter) could cause a sudden outage — more likely at night when the lights are on and consuming power — of the most vital system of the car.
There are people who know how to do this stuff and there’s a whole Internet’s worth of information on the subject, so there’s really no reason to make a bad or uninformed decision.
For the 1963 Corvette, most of the wiring harnesses are available. Aesthetically, I just wasn’t going to put dirty old wiring into a car filled with brand-new parts.
You can do the wiring yourself, but it takes time to get it tidy. This ‘before’ picture of our 1963 Corvette is the opposite of tidy.
Address wiring issues first, before chrome and horsepower
From a safety and reliability standpoint, wiring is one of the first things that should be addressed, right along with brakes and suspension, but it’s out of sight and out of mind until something happens, and definitely out of budget when shiny wheels and horsepower parts seem to get all the funds.
The engine harness and the forward lighting and rear lighting harnesses are the most obvious and likely the most easily attainable through aftermarket suppliers.
The steering column, which also happens to be full of moving parts, represents a trickier proposition, unless you’re transplanting a new aftermarket unit with new signal switches, clean contacts and goodies like a tilt option.
The steering column’s operation depends not just on good wiring, but smooth and reliable movement and operation of the controls. It’s wise to at least consider a replacement column so that everything is new and safe.
Even after going through our stock Corvette steering column with a fine-tooth comb, it still creaks and groans and the signal switch is a little spongy. It will likely take a lot more time with the column out of the car and on the bench to get it working just right.
Honestly, an aftermarket piece from Ididit is looking pretty good right now, especially considering that the horn still doesn’t work properly.
Avoid tragedy: All wiring, no matter how extensive the restoration, deserves inspection
Dash switchgear and instrument circuitry are usually plug and play – fairly straightforward as new parts and pieces if you can find them.
Depending on how meticulous the restoration is — if it’s down to repainting the dial tips the right shade of fluorescent orange — then you’ll no doubt be cleaning and inspecting all the parts and pieces during that process. At the very least it all deserves an inspection to prevent tragedy.
The point is to be just as meticulous with the things you can’t see as those you can, such as a shiny paint job and wheels.
I paid about $900 for new harnesses plus installation, an amount that should be factored into any project. This is the mark of a vehicle that has been truly restored and not one that has merely been polished to look good.
For the rest of our East Coast Garage series on rebuilding a 1963 Corvette, please click here.
For radical transformations of old cars to include electronic fuel injection and new gauges, it’s often easier to begin with whole new aftermarket wiring harness with a high-capacity fuse box. This is a system from a company called Painless Performance for our 1970 Plymouth project car, also featured in East Coast Garage.
