If you’re performing a complete restoration and have followed the book to this point, your Corvette is in the final stages of its journey. The body has been repaired, filled, sanded, primed, and now shines with a new paint job. Your rebuilt engine has been reunited with your refurbished frame.
Before reuniting the body with the frame, install the interior back into the completed body. Or, you can wait until the body has been mounted onto the frame. The advantage of waiting is to reduce the weight of the body when it is lowered onto the frame. It is your choice.
This Tech Tip is From the Full Book “HOW TO RESTORE YOUR C3 CORVETTE: 1968-1982“. For a comprehensive guide on this entire subject you can visit this link:
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The first thing to do is clean the body and interior and lay out the new carpet on the floor to relax the folds from being stored in a box. I decided to install the interior into the car first because it fit into my schedule better but you can do this in any order.
Wiring Harness Installation
Step-1: Inspect New Harness
Third-generation Corvette wiring harnesses are available in four major sections: dash, engine, forward lamp, and rear lamp. Depending on the condition of your existing harnesses you can replace any section that is worn or faulty with a new harness and plug it into the rest of your existing system. This new dash harness was purchased from Lectric Limited, which specializes in producing factory replacement wiring harnesses. It is being installed into a 1972 Corvette and will be plugged into the other original wiring sections.
Step-2: Install Rear Wiring Harness
The rear wiring harness was carefully marked with tape at each connector when it was removed. This makes reinstallation much simpler and enables the connectors to plug into their proper locations quickly. Tug on each connector to make sure it is secure. Make sure the wires and connectors are safely out of the way of any screws that may be installed later.
Step-3: Install Lamp Socket and Switch
The passenger courtesy lamp socket and door light switch install into the passenger’s side of the dash before the panels are installed. It is much simpler to complete this task with the dash removed from the car.
Step-4: Attach Gauge Cluster Wires
The color of the wires that go on the back of this cluster are stamped into the back of the housing (gray, light blue, etc.). Install new bulbs while you’re at it. The tachometer drive connector attaches to the center opening on the back of this cluster. This connector is spring loaded and snaps into place when it is in the correct position.
Step-5: Plug in Headlight Switch
After the headlight switch is installed, locate the headlight connector and plug it into the switch. Again it is much easier to perform this task with the dash panel removed from the car.
Depending on your situation, reconnect your existing wiring harnesses or replace any damaged or worn ones with new harnesses.
The third-generation Corvette was produced over a span of 14 years. During this time, the country underwent a social shift with a better awareness of emissions and a dramatic rise in gasoline prices. Corvette engineers were forced to squeeze more efficiency out of engines and transmissions to improve mileage. Horsepower declined from a high of 435 to a low of 165 in 1975. It finally stabilized at 200 during the C3’s last year of production in 1982. Meanwhile, Corvette customers demanded to have more comfort and convenience features added to the optional equipment lists. By 1981, the number of electronic engine controls continued to increase and the engine was controlled by an on board computer.
The demand for additional optional equipment and electronic engine controls greatly added to the later C3 wiring complexity. As a result, the wiring harnesses had to include plugs for optional equipment whether it was installed in the car or not.
As you begin reconnecting your wiring harness, you may find it has unused connectors. This depends on the year of production and the factory-installed optional equipment on the car. This is why, in Chapter 3, I recommended that you tag each electrical connecter as it was unplugged. Whether you reuse your old wiring or replace it, this makes your rewiring job much easier and more straightforward.
Before installing new carpet, route all of your wires inside the cabin and back to the rear of the car. A GM Factory Assembly Manual for your year car is very valuable for reconnecting the wiring, and it is much more detailed than a GM Shop Manual. Assembly Manuals are available from restoration parts suppliers and are well worth the money to have on hand.
The connectors and sockets usually fi t into one item that requires a power feed. Installation is much easier as long as you marked your connectors when you removed them from the car.
It is best to lay the wires into the interior and route them under the dash, under the center console, and along the sides of the door frames. Once the body has been reunited with the frame and everything is hooked up, you are able to test the operation of your electrical system.
As long as everything was plugged in correctly, each item should work as designed.
You may find that you didn’t secure a connector tightly enough or a bulb is burned out when you put power to the system. You can correct these missteps with some simple troubleshooting. A handheld voltmeter with probes can help you tell if a connector is getting its required voltage. This helps you trace that circuit back to its source to determine if it is connected correctly. Before you begin troubleshooting, gather a few handy tools. First select an assortment of automotive fuses that fit your Corvette’s fuse panel. You also need a self-powered test light; it looks like a small screwdriver that glows when it is inserted into a wire connector. Also get a test light with a bulb on one end and two probes on the other side; it verifies whether the circuit is getting voltage. An inexpensive voltmeter is a must before you proceed. A small, strong fl ashlight helps you see wires and connectors that are located in tight places. Be sure to have a wiring diagram for your year Corvette on hand. To round out the list, you need a spray can of electrical contact cleaner, contact grease, a small screwdriver, and a good set of eyes.
A typical circuit inside a car is composed of a battery, conductors (wires), fuse, switch, load, and ground. Typically only four things can cause a circuit not to work: an open circuit, short circuit, high resistance, or an accessory that is defective.
An open circuit is created when no power is fl owing from the power source (battery). This can be caused by:
- Blown fuse or circuit breaker
- Broken wire or broken connector
- Open switch or faulty bulb
- High resistance from a shorted wire or accessory
To find an open circuit carefully inspect for kinked or broken wires. Also look for a wire with damaged insulation that might be touching a metal part. Corroded connectors or terminals cause high resistance and blow fuses. Blown fuses and popped circuit breakers are an indication of an open circuit. Their job is to protect a circuit from overloading, which causes heat that eventually melts the insulation on the wire and causes failure.
A blown fuse is an indicator that a problem exists within the circuit, and the fuse is there to protect it. If the fuse didn’t blow, a fi re or thermal event is possible.
Your troubleshooting should begin by tracing the faulty circuit from the fuse to the electrical device it powers. Your electrical system has two fusible links that interrupt power from the battery if it detects an unusual surge. These links are usually located above the starter solenoid. Be sure to check these if power is not getting into the cabin.
When a circuit receives more power than it was designed to handle, a short circuit blows the fuse that protects it almost immediately. Do not replace one fuse with a larger fuse (say, 10-amp with a 15-amp fuse) to get the faulty circuit powered up. This can cause a fire.
Depending on the type of short you are encountering (wire-to-wire or wire-to-metal), you may get odd symptoms. You could turn on a headlight switch and the windshield wipers might start working instead.
Damage or wear from a wire being pinched by clamps or pushed against a piece of sheet metal usually causes short circuits. A connector poking through the wire or a wire routed over a piece of sharp metal that eventually wears through the wiring insulation could also cause it. It is important to locate the fault quickly to minimize any further damage to the electrical system.
Also, circuits can become shorted by an internal problem in the device it is powering, such as a radio or power window switch. Always look for damaged or frayed wires or a burning smell that is emitting from an accessory.
This is caused when a circuit is exposed to a higher load than it was designed to handle. It occurs when a connector is loose, corroded, or not secured to the power terminal correctly. A circuit that has high resistance can dim light bulbs and cause other circuits to run slower. If a ground becomes loose or corroded, it can create high resistance on that circuit. The problem could become so acute that none of the accessories on that circuit function.
A discolored light or a fan making a loud or unusual noise indicates a potential failure. Make sure it is getting the correct amount of voltage and the connector is tight. The repair might be a simple matter of replacing the lamp or switch or fan motor to get everything functioning normally again.
Isolating the Problem
Here’s a simple example to isolate a problem. Let’s say a taillight is not working. The first thing to try isto replace the bulb. If it works, problem solved.
But what if none of the taillights are working? If you have checked the bulb’s fuse and the connectors and still nothing, now is the time to look at the power source to find the problem.
With most electrical problems, just use logical deductive reasoning, and then be thorough and methodical as you inspect, measure, test, and verify the equipment. After all, the best tool is the gray matter between your ears.
Corvette interiors also evolved during the C3’s long production run. From 1968 to 1976 vinyl interior was standard and a leather interior package was optional. In 1968 and 1969 the leather upgrade only included the seats. This option was expanded in 1970 with the addition of cut-pile carpeting, wood grain accents, and carpet trim on the door panels. In 1977 leather seating became standard and the upgrade was included in the base price of the car.
In 1978 the seats received a major upgrade when a pace car was ordered. The pace car interior included redesigned clamshell seats that folded flat on the passenger’s side. The new seats featured bolsters that provided more support for the passenger and driver. They were an instant hit and became standard in all Corvettes from 1979 to 1982.
1968–1977 Dash Installation
The dash panels in 1968–1977 Corvettes are different than those in 1978–1982 Corvettes. These earlier cars feature a three-panel dash system that includes the driver-side console, center stack, and storage pockets in front of the passenger. The top of the dash is a separate piece held in place with screws and a series of clips that attach to the lower windshield frame.
If you have misplaced or damaged interior screws, you can order a complete screw package from any aftermarket Corvette warehouse. If your screw holes are enlarged, do not use a bigger screw; instead purchase drywall plastic plugs (like the ones used to hang photos on the wall) from any hardware store. They come in a variety of sizes. Insert them into the enlarged hole to fix the problem. You can use them on any interior reassembly.
The instrument cluster consists of a large tachometer and speedometer. They are enclosed in a metal frame that attaches to the dash panel. The driver-side dash panel also includes a headlight switch on the left and manual head light door and head light override switches under the steering column. This panel includes the ignition switch on 1968 Corvettes. It is best to assemble and install this side of the dash first. Remember to plug in all of the connectors for the tach and speedometer cables before screwing the unit into the dash frame. The center stack holds all of the critical engine instruments as well as a clock. All of the correct wires should be attached to this stack before mounting it into the dash frame with screws.
At this time, you should install the radio because the passenger’s side of the dash is still open, so you can reach around and connect the radio wiring and antenna.
This is now a good time to install the top dash panel pad. Carefully slide the clips into the windshield frame and lower it onto the driverside console and center stack. Secure it with Phillips screws that you stored during disassembly.
Complete the dash installation by mounting the passenger-side dash cover.
Dash Pad Installation
Step-1: Install Instrument Cluster
The instrument cluster that includes the tachometer and speedometer is installed onto the driver-side dash panel first. Next plug in the bulbs, wires, and tach, and attach the speedometer cables. Secure the dash panel into the instrument panel frame; it’s much easier to complete this procedure with the steering column removed. All of the wires should be in place before the dash panel is installed. Use a Phillips screwdriver to install the two screws that hold the driverside panel in place, which is near the steering column.
Step-2: Connect Instrument Console Wires
Plug in the color-coded center console instrument cluster wires (your previous tagging should make this task straightforward). Once the power connectors are plugged into the cluster install the unit into the center opening of the dash. This is a good time to install the radio because you can reach behind it and hook up the power and antenna connections. The dash pad with the two factory speakers is seen in the foreground of the photo.
Step-3: Install Dash Pad
Once the center cluster is secured, lock the top dash pad into place against the windshield. The top dash is held in place with a bolt that is attached underneath the pad to a bracket on the passenger’s side. Use a 5/16-inch socket to tighten it. Steel clips and screws hold this panel in place. Finally, the right side of the dash with the map pockets is installed and screwed into place.
Step-4: Inspect Finished Dash Pad
The completed dash should look like this. The non-factory radio sticks out from the dash, but offers the owner a larger choice of entertainment options.
1978–1982 Interior Installation
Except for the dash panel, the entire interior on our 1980 Van Steel subject car was removed. This included the steering wheel and steering column. The original interior was not damaged or torn but was soiled in some places and the original color was starting to fade after many years of being exposed to the Florida sun. Corvette America provided all necessary new interior parts.
The installation procedure is really just a reversal of the removal process in Chapter 3. Start by installing the center and instrument cluster. It is much easier to perform this task with the steering wheel out of the car. If some of the original engine compartment wires are frayed, you need to install a new harness. (The wiring in this car was left intact with the exception of the engine wiring, which was replaced with a new harness from Lectric Limited.)
Next, return the steering wheel and column to the interior and attach its wiring. The wiring connectors plug into the side of the steering column and each one is different so you cannot install the wrong one. The steering wheel is held in place at the firewall and under the dash.
The various plastic trim panels that surround the windshield and the overhead passenger compartment are next on the list.
Then install the carpets in the driver and passenger compartments. These are preformed pieces and fairly simple to install. They are held in place with the doorsill and a center cover that attaches to each side of the console. The large carpet piece that fits behind the seats and into the cargo compartment should be installed next. The vertical piece in the rear attaches to a rod beneath the window that holds it in place.
The rear carpet is much easier to install in 1978–1982 models because of the large rear windows. They allow room to crawl into the back to secure everything.
When the carpet is in place install the two rear speakers if your car is equipped with this option.
Finally, install items such as the cargo compartment cover, seat belts, seats, and door panels.
Interior Component Installation
Step-1: Install Steering Column
Return the steering column to the interior but do not secure it until the driver’s instrument cluster is installed. Connect the speedometer cable onto the back of the cluster, which is held in place with a snap clip. The speedometer cable can be secured by pushing on the bottom of the clip to lock it into place. Plug the power cable into the back of the cluster and then attach it to the dash with Phillips screws.
This job is much easier with two people. One can hold the column in place while the second person attaches the wiring and nuts. Two 9/16-inch nuts under the dash and two 1/2-inch nuts on the firewall hold the column place. First install the two 1/2-inch nuts on the firewall studs. The steering column should be low enough so that the wires can be plugged into the side of the column. Each bundle of wires must be matched with the plug on the column.
Once the wires are attached push the column onto the two studs under the dash panel. Secure it with two 9/16-inch nuts and tighten them to 30 ft-lbs. Tighten the two 1/2-inch nuts that are on the inside firewall above the brake pedal. Use a long extension to torque them to 25 ft-lbs. Reinstall the lower cover after hooking up the headlight-override vacuum switch.
Step-2: Install Upper Trim Panel
The upper panel trim is attached with Phillips screws and bolts. The center trim piece (shown) is held in place with the overhead light holder. Two 7/16-inch bolts hold this light socket in place. Continue installing the upper roof and windshield trim with Phillips screws.
Step-3: Install Front of Console
The front of the console is secured with two 1/4-inch nuts and must be attached when reinstalling the cover. It is helpful to locate these nuts with a mirror before attempting to tighten them.
Step-4: Inspect New Seat Covers
Art Dorsett ordered a complete new Doeskin 1980 duplicate GM factory interior from Corvette America that matches his original factory installed leather. The set includes new driver- and passenger-side leather covered seat cushions, door panels, carpet, and armrests. The interior will look factory fresh when it is completed.
Step-5: Inspect New Carpet
Remove both passenger- and driver-side carpets from their boxes to lay fl at on the floor. (They will be held in place with the lower door trim cover.) Do the same with the rear cargo carpet. It is best to leave them in this position for a while to enable them to regain their shape.
Step-6: Install Front Carpet
The replacement carpet sections are preformed and fit into the car with only minor trimming. The driver-side carpet is held in place with the side door trim plate and the center console carpeted cover (not yet installed when this photo was taken).
Step-7: Install Rear Carpet
The rear cargo compartment carpet comes in one molded piece. The front of the cargo compartment is covered with a form-fitted piece of carpet that fits behind the seats and console cover. Carefully push the carpet into place and secure the rear of the carpet at the back of the rear luggage compartment cover. The back of the cargo compartment is held in place with a U-shaped retainer that must be clipped onto a rod that runs across the top, underneath the rear luggage cover. Once it is clipped on one end it is easy to slide it onto the rod. On 1968–1977 Corvettes the rear carpet is five separate pieces, driver/ passenger-side, fenderwells, rear bulkhead, cargo area, and the piece behind the rear seats. They must be installed as individual pieces. The back piece is glued onto the rear bulkhead. The original carpet on the 1978–1982 Corvettes was not glued and may need to sit for a while to return to its factory shape.
Step-8: Install Cargo Compartments
All 1978–1982 rear cargo compartments have two storage bins (1968–1977s have three). These bins are held in place with up to 10 Phillips screws. They must be installed after the rear carpet is in place. These storage bins help the carpet stay in place.
Step-9: Install Center Cluster and Carpet
The center cluster on later C3 Corvettes have much-improved wiring systems. Each instrument is attached to a central connector with copper wiring that is impregnated into a plastic sheet. One main plug powers all of these instruments (shown). After the cluster is installed attach the two side console carpet covers with three screws on each side. It is best to find their location before installing them. One easy trick is to insert a small piece of wire through the hole to help locate the attaching brackets. One screw is in the back, one is in the middle, and one is in the front.
Step-10: Install Mirror Controls
All 1978–1982 Corvettes that are equipped with optional remote door mirror controls include an adjuster held in place with a metric setscrew. This setscrew must be tightened after the door panel has been installed. Install the armrest and door pull cover and push the lower panel into the door clips to secure it to the door. A metal channel runs along the top of the door panel. Slide this into the top of the door frame, which allows the door panel to hang on the door. Use the clips (or screws on 1978–1982 models) to attach the panel to the door frame. The seats are the last items that need to be installed into the interior. Attach a metal bracket with four attachment points to the seat. Each seat sits on top of the carpet and is bolted to the floor in the front and rear with four bolts. The cushions are held in their individual buckets with spring-loaded clips.
1968–1975 Convertible Top Installation
Corvette convertible production outsold coupes only in the first year of C3 production. Each year thereafter the coupe outpaced convertible sales. In its final production year in 1975 a total of 33,836 coupes and only 4,629 convertibles were built. Today C3 convertibles are highly desirable to own. Those that include both the optional hardtop and the convertible top are the most sought after.
Installing a new convertible top is not easy for a novice installer but it can be done. The top needs to be tightly mounted and stapled onto the steel frame, but still allow enough flexibility to fold efficiently into its storage well behind the seats.
Convertible Top Installation
Step-1: Install Convertible Frame
Corvette convertible top steel frames are attached to the frame behind both seats with four bolts. The frame consists of ribs that are hinged on the sides so that they fold fl at when the top is stored in its compartment.
Step-2: Attach Vinyl Strips
Before the top fabric is installed two panels are attached to the frame. These panels consist of vinyl strips that cover two large foam pieces. The vinyl is stapled to the frame and the foam is spray glued onto the vinyl. The vinyl is folded over to cover the foam and stapled to the frame.
Step-3: Stretch Top and Remove Wrinkles
Premade tops are available from most major Corvette aftermarket suppliers. They are shipped preformed and designed to correctly lay over the car’s steel frame top. The trick is finding an upholstery expert who has the knowledge to correctly stretch the material so that it is free of wrinkles.
Step-4: Inspect Complete Installation
The completed top should fit tightly and be free from wrinkles when it is in the up position. A correctly installed top provides many miles of good service, such as the top on Ron Bray’s 1971 convertible.
Many aftermarket Corvette suppliers sell premade convertible tops. These tops include the rear window and panels that are fitted beneath the top to provide support. This material is attached to the existing metal frame with staples and screws; it usually takes an experienced installer about 3 to 4 hours to complete the job.
A leak-free convertible top adds a lot of driving pleasure to your Corvette experience. If you don’t want to do the work yourself, shop around to find a competent professional installer. Don’t be afraid to talk to some local Corvette clubs to get some recommendations before making your final selection.
Written by Walt Thurn and Posted with Permission of CarTechBooks