Six Tips for Rewiring Your Classic Car
Automotive electrical systems have never been for the faint of heart, and rewiring a classic car's interior is sometimes a challenge. The good news is that classic cars have fewer electric accessories - power windows, door locks, sun roofs, etc. - and probably no electronic relay boxes. The bad news is that in most cases a complete restoration will require that everything electrical be replaced. The following are six tips for rewiring a classic car for do-it-yourselfers.
One: Replace everything. Wire degrades. Metal may have flexed apart or severed inside the insulation where you can't see it. Insulation may look okay on the outside, but may be worn so thin in places that it will wear through and short out the wire almost as soon as you put the car back in service. A good restoration job leaves nothing to chance.
Two: Schematics don't tell all. Even if you have a schematic and know how to read it (they can seem like hieroglyphics to some), remember what they don't show. Principally this is: how do the wires get from Point A to Point B? Do they run in a channel along the floor of the passenger compartment? Above the door frame? Underneath the ceiling liner? Carefully note this as you're removing the existing wiring. Remember also that although the wiring may have been well thought-out at the design and manufacturing stage, what is most efficient on the assembly line isn't always the best route. There's room for creativity here, assuming you document it well for future repair needs.
Three: Take copious notes. Don't disconnect or pull out anything without writing down the details. How long is the wire? What color? What does it attach to on each end? Is it spliced into anything? Where does it run? If, for instance, it passes through the trunk, how does it get in? Even your own makeshift drawings can be very helpful later. Imagine what information you would want if you bought or inherited an already-restored vehicle. Then write it down.
Four: Label the new as well as the old. Get some masking tape and a sharpie. As you disconnect each wire, label each end - and label the terminals it connects to. That's obvious. But, do the same with the new wires and components. That way when you go back later, either to repair something, or troubleshoot, it's easier to find and trace the appropriate circuit. The time it takes now, while it's fresh, will save lots of time later when you have to reconstruct what you did.
Five: Test components outside your classic car's system. If you know whether a socket and bulb work before you wire it up, you don't have to worry later about whether a malfunction is in the component or in your new wiring. This allows you to focus your troubleshooting efforts. A 12-volt power supply with leads with alligator clips serves this function well.
Six: Bundle. Pre-manufactured wire harnesses are probably not available for anything old enough to be a classic. So as you're wiring, make your own. When you have multiple wires running parallel to each other, bundle them together with plastic zip-ties. This makes the wiring stronger, less prone to bending and breakage, is a more efficient use of space, and avoids loose strands that can catch on things.
Critical Point: This should go without saying, but be sure to disconnect the battery before you start. Twelve volts may not be a lot, but the thirty amps a battery can produce during a load is enough to cause serious injury.
If you've got classic car rewiring questions or want to consider having professionals do it for you, call a professional restorer now for a confidential, free estimate. Classic Car Restoration Services have the experience and equipment needed to turn your project into something you're proud to drive.