Street Rodder Magazine's "Guide to Building Street Rods"
-- Electrical & Interior
By Jay Storer
Photography by Brian Brennan
The electrical system in your street rod should perform to the same standards as the one in your late-model, everyday car. That is to say, it should work flawlessly, invisibly, and if a problem ever does arise, the system should be logically laid out and easy to troubleshoot.
Street rodding has advanced enormously since the days when rodders had to create their own electrical systems with mismatched components and just three or four wire colors. We now have a number of companies devoted exclusively to electrical systems and components for hot rods. With a pack- age like the one we used from Painless Performance Products, anyone who can assemble their own street rod can install the complete electrical system.
The benefits of today's kits are that all the component sourcing has been done for you by Painless, and the parts are compatible and have the proper ratings to be safe for automotive use. The fuse panels are based on standard Detroit OEM designs, but are compact enough to work in the often-crowded under-dash area of a street rod. Our Deuce highboy roadster was fitted with the Painless Performance "Universal Streetrod Harness" (PN 10102), which offers 12 circuits and is their popular kit for applications with a GM-style column. It you have a more accessory-laden application, they also offer kits with 18 circuits. In fact, there are a number of other options in their line, including kits designed specifically for pickups (longer rear harness), for cars with non-GM steering columns, and for vehicles where the fuse panel is to be mount- ed in the trunk rather than under the dash.
Basic Electrical System Installation
You can expect to consume some 20- 40 hours when installing your electrical system, depending on the application and your experience. After you have read the instructions, maybe even twice, you can call the Painless Performance Tech Line if you have further questions before starting, (800) 423-9696. Remember, "There are no dumb questions, only dumb things people do when they don't ask questions."
In addition to the standard electrical tools you may already have, such as a test light, electrical tape, and a quality wire crimper/stripper, you should also have a low-amperage source of 12 volts you can use to temporarily power up a circuit to check things (e.g. a two or three amp "trickle" charger). You could also duct-tape together two 6-volt lantern batteries in series for a cordless 12-volt test supply you can take anywhere.
The fuse block is the core of the whole wiring system, so when you're ready to start, pick the best spot for the panel and mount it, taking into consideration leaving room for other components that may have to fit in the same area. Now you can start unrolling the huge coil of colorful wires that are pre-attached to the back of the fuse panel. There's quite a bit of weight in the system, so you need a sturdy mount for the fuse block as well as harnesses that are amply supported along their routes so connections at the fuse panel aren't under a strain.
Separate the wire bundle into the several sub-harnesses and roughly lay them out in the car according to where they must go. The three main wire destinations are the front of the car, the center of the car (dash), and the rear of the car. The front group bundles all the wires that go forward to the engine and the front lighting. This includes wires for the starter, alternator, distributor, engine gauge senders, electric cooling fan, and air conditioning, The lighting wires encompass high/low beam for the headlights, park and turn signals, and the horn, since this is usually mounted at the front of the car.
In most cars, you'll have to take a hole- saw to the floor or firewall to make a hole big enough for the large supplied grommet to route the front harness through. From there, you can roughly separate and lay the wire groups in their approximate final positions near the lighting and engine destinations. Do not cut or attach any wires at this time, but it's a good idea to install some support clamps to the big bundle where it comes close to the fuse panel.
Follow the same procedure with the harness that goes to the dash area itself, securing the bundle up and out of the way for now. At some point you will have to make provisions under the dash for zip- tying these wires, and on some cars that means adding a length of tubing to serve as a cowl-wide mounting base. You're still just doing the rough layout here, so tackle the last major group next: the wires that run to the rear of the car. Here you'll have to decide the safest route, which is away from anything that could cut or chafe the harness and away from hot or moving components. Most installers run this harness down the center of the floor and once past the seat, they divert the wires to where they need to go.
There are several ways to secure wire harnesses to the interior of a car. When you're just planning the rough layout, duct tape works great for "training" the harness to stay where you want it, but eventually you will want something more secure. The most common method of securing a harness is with plastic "buttons" that have a self-stick back. These can be attached anywhere there's a clean surface, even inside a fiberglass body. The side without the sticky back has a small loop through which you can insert a tie-wrap for securing a bundle of wire, or just one or two.
When you are starting to layout your wires, you should only loosely secure the harnesses to the plastic mounts with the tie-wraps; this is so you can add or subtract from the bundle later.
Besides the main harness grommet at the firewall, you will be using grommets at any point in the car where wires must pass through another material, like sheetmetal, fiberglass, wood, or card- board interior panels. Past the firewall grommet, the wiring that goes forward for the engine and front lights is considered "exposed" wiring, meaning not just that it is visible, but that it's subject to extra heat, water, road salt, dirt, oil, or grease. You'll want to cover these wire harnesses in some kind of sheathing, both for looks and protection.
The three avenues usually taken for wire protection are electrical tape, plastic split-loom, and shrink-tubing, and all of them will work. It's more a matter of personal preference. Split-loom (available in your auto parts store) is the easiest harness covering to open up to check a wire or to add subtract from the harness. Tape is simple, but not as easy to open up if you need to, and shrink-tubing is very neat and protective, but the most difficult choice if you have to open the bundle in the future.
Protection from shorts or overloads in your system takes several forms. The most basic is the simple fuse. A circuit for a radio may only a need a 3-amp or 5-amp fuse, but circuits with electric motors (power windows, etc.) may need a 20-amp fuse. Each circuit has a fuse of a capacity suited to the current load, and if there is a short somewhere because a hot wire was punctured and grounded, the fuse burns out and immediately shuts that circuit off. If that happens, you need to start looking over that circuit to see what the trouble might be before you put in a new fuse. And anyone who works on cars at all should know that you never replace the fuse in a circuit with a higher-rated fuse; you're just asking for escalated trouble!
Fuses come not only in different ampere-ratings but also in different sizes. Our Painless panel has lots of standard "miniature" fuses but for extra insurance the system also has a "Maxi- Fuse." In our case the heavy 1 a-gauge hot wire from the starter supplies all the juice to our panel, so Mark wired the Painless Maxi-Fuse into that wire between the starter and the panel. Ours is located in the left kick-panel area and should anything happen to the starter or the wire to cause a short, the Maxi-Fuse will shut off everything.
There are other forms of protection for switches, especially in circuits that have motors. Starting a motor takes a lot of current, and this poses a heavy load on a switch. To keep switches from burning out, the standard protective device is a relay, which is like a heavy-duty switch. In use, the high-amperage load to the motor is handled by the relay, while the switch handles only normal low-amperage current to tell the relay to open or close. Relays are included in the Painless kit for most basic needs, such as halogen headlights, electric cooling fan, electric water pump, and electric fuel pump. If your car has power windows, seats, or power door locks, those circuits would also need relays. A third type of protective device is a circuit breaker. This works like a fuse but instead of burning out, the breaker can be reset after it has tripped due to a rise in circuit temperature.
When you definitely have every wire in your system kissin' close to where it connects, you can begin to cut, crimp, and attach wires to complete the circuits. This is perhaps the most time-consuming portion of the electrical installation, but don't rush things. Using solderless connectors makes wire connection easy and secure, but there is a right and wrong way even in this simple procedure.
Before any wire can be terminated, you must strip the insulation from the wire end and here's where you can benefit from a quality tool to strip the many wires you will have to work on. The wire should only be stripped of enough insulation to insert the wire into the solderless terminal, no more or less. Insert the terminal in the jaws of the tool and hold it there without crushing it, then insert the wire and squeeze. Crimping tools have an arrangement of a semicircular "saddle" on one side and a prong on the opposing side. When you squeeze the terminal between these jaws, the wire should be neatly and securely encased. If you look at the end of a solderless terminal very closely, you'll see that one side of the tubular area the wire goes into is split. This split part of the terminal should always be placed face-down in the "saddle" of the tool when crimping or the seam may actually open, which you won't notice because it is covered by the plastic insulation on the outside.
In some cases there are electrical components that need several wires attached and it's more convenient to use a factory type plastic plug that has all the wires in it. In our Painless kit, such plugs were provided for the dimmer switch and the headlights. Painless supplies two headlight harnesses that are separate from the main harness and have the proper connectors on them. So you just plug the connector onto your headlight bulb and use butt connectors to attach the marked wires from the harness to these three wires.
Department of the Interior
It's all well and good to have a beautiful car with a great engine and cool wheels, and if you trailer it everywhere you go, then maybe that's all you need. But STREET RODDER's annual rod is called the "Road Tour" car, and for packing on the miles as this one will do, you need more than just nice material inside the car, you need a comfortable interior. If the style you're going for with your street rod is of the high-tech smoothie genre, then there are essentially no rules. You will probably have a top-notch upholsterer carve a whole free-form interior shape from metal, wood, and foam, then apply the padding and luxurious materials over it. This can be designed precisely to fit your body and your preferred driving position, all the while looking radically chic.
In a more traditional roadster like ours, you don't have the option of this kind of tailored-to-fit look for the interior, so there are fewer choices. Yes, you could have your local upholsterer build a wood, metal, and foam seat, but it would have to conform to one of the simpler, traditional interior looks of a roadster. The interior look assumes that much more importance when it's right out in plain sight. Remember, when you're topless, everyone is looking!
Randy Clark (Hot Rods & Custom Stuff, Escondido, CA), the builder of this year's Road Tour roadster, is a guy who doesn't like to farm out much work on the top-quality cars he produces. He's lucky enough to have upholsterer Paul Arnold on his staff, so the whole project could remain under Randy's eye and direction at all times. Paul made all our panels, did the insulation, padding, upholstery, carpeting, floormats, and more.
The only parts of your car that you're in 100 percent contact with at all times when driving are the steering wheel and the seat, and you may occasionally take one hand off that steering wheel. That leaves the seat surface as pretty central to comfort on the road. Once again, our street rod aftermarket has come up with some great choices for seating, with well-constructed steel frames and various options I to accommodate almost any shape of driver or street rod.
Our choice was Wise Guys Seats & Accessories (Elkhart, IN), who supplied us with a great seat and a large hide of leather for all of our interior panels. Their '28-34 seat fits roadsters, coupes, and sedans, and has standard features like a seat back that reclines or tilts forward to access the area behind the seat. It's also got a seat bottom that lifts up so you can stow maps and stuff under there. Wise Guys has some pretty "cushy" options for their seats; you'd think they were for Cadillacs instead of hot rods! You can get seat heaters, power slide adjuster, power or mechanical lumbar adjuster, and a fold-down center armrest. Ours arrived from Wise Guys with the leather already done. With the combination of metal springs in the seat bottom, the shaped foam, and the supple leather, everyone who's tried the roadster agrees it's one comfortable perch for two!
Paul began our project under a tight deadline, but that didn't keep him from taking the time to make careful measurements for every panel. It's hard to find a huge black cow with a perfect hide free of marks, so leather is very expensive-you want to measure three times, cut once. Paul likes to work "from the top down," meaning he makes the panels first, then the seating, then the flooring. The panels for the upholstery begin with 1/8-inch thick wood. This isn't the "groovy" paneling you see on mobile home walls, but rather smooth "luan" meant for skinning household interior doors. It comes in 4x8 or 3x7- foot sheets. When used for car interior panels, they provide a stiff, durable backing that can conform to the gentle curves of doors and other interior areas. The wood sands easily and will not chip out or warp from moisture (definitely a factor in a roadster) as can happen with black cardboard upholstery panels.
Fastening the wood panels to the car is accomplished by the time-honored method of using spring clips that fit into holes on the door or other area being covered. On our car, the Brookville doors have all the stock clip holes already in place, so Paul just attaches the roughly sized wood panel with two clips, then traces the door edge on the backside of the wood. With the panel off the car, he cuts it to size with a fine blade in a sabresaw. With the clips in place on the panel, you just align the spring ends of the clips in the holes, then gently push on the panel and it snaps into place. Go all around the panel and it stays snug, yet when it comes time to remove the panel, using a dull, flat-bladed trim tool under the panel allows you to pop the spring clip out without any damage to the wood panel. Spring clips can sometimes pull through a cardboard panel after it's been on the car for a few years.
Our interior features smooth, black leather for real style and that "shoe store" smell. Once a panel has been sanded and fitted with the clips, Paul uses thin self- adhesive foam padding on the interior side. The foam keeps the heads of the clips from showing through the upholstery material, and gives the finished panel a softer look. However, the foam must be trimmed off flush with the edge of the panel, not wrapped around, or it will make the panel edges too bulky.
One of the professional upholsterer's most used tools is his spray gun for applying glue. This isn't drippy liquid but a contact-cement kind of adhesive that has a limited working time after it's sprayed onto the material, and usually holds for the life of the upholstery. As with household contact cement, it works best if you spray both sides to be adhered, wait until its tacky, and then stick the two pieces together. Paul spray-glued the foam on our panels and the backside of the leather piece he had cut to be just big enough. He positioned the door panel directly over the backside of the leather, then dropped it in place. Flipping the panel over, he smoothes the leather and pulls out any place that may have a wrinkle, then flips the panel over again and snips the perimeter of the leather's overhang so that the pieces can be tugged onto the back of the panel and pressed in place.
This all sounds simple so far, but the finesse comes in attaching the material to the back of the panel without wrinkles. The corners require the most experience, knowing just where to snip-and- stick. Inside corners, such as around the pocket in our '32 door panels, are especially tricky. The routine thus far described was used for making, covering, and installing all of our interior panels, including those in the trunk.
Floor covering for a rod is another art of the trimmer, unless you happen to have a completely flat floor. Again, for you and I it begins with perfect templates, which are transferred to the backside of the carpeting. Many professional trimmers have enough experience that they can rough- cut a piece of either the carpet padding or the final carpet and just start laying it in the car, They mark areas with chalk like a tailor and snip until they have a perfect fit.
The padding is lightly glued into the car, but the carpet is removed and brought to the big sewing machine where a binding or edge trim of a different material, like our leather, is sewn over the edges. When it's finished and installed, the result is a factory looking floor! In our Deuce, Paul also padded and carpeted our entire trunk.
With the Wise Guys seat and our leather-skinned panels in place, the only "softwear" left to deal with was a top. We used a commercially available hot rod top that folds up and can be stowed in the trunk. Once the folding top frame has been adjusted to fit your car and the material fitted to your head- er, it's a matter of minutes for one guy to put the top up while pulled to the side of the road.
Design, construction, powertrain, paint, wiring, and now upholstery-the end of our project is in sight and we can almost feel those highway ridges clicking the miles under our tires!