Corvette Technical Answers

  • Finding the best books to guide your Corvette projects

    Zip often receives calls from folks who have just acquired an older Corvette and are looking to purchase a book or two for reference. The big question is "What book would be best for my Corvette?"

    Tom Richardson, Zip Sales Associate offers the following advice:

    Luckily, there are few cars that have as much written about them as the Chevrolet Corvette. But with all of the choices and variety, how do you know which book or books will have the information you need?

    Of course, it depends on your situation. Building a judged show car is a much different process than diagnosing a mechanical problem and fixing it, and the reference materials used for each situation are just as different.

    If NCRS judging is in the cards, then the NCRS Judging Manuals should be considered required reading. With descriptions of all of the judged components throughout the Corvette, these manuals are the ultimate authority when it comes restoration accuracy. Need to know if the wiper arms should be dull or shiny for your mid-year or what the correct style screw should be on your exhaust bezel? The NCRS books have these answers and many more. These manuals are not heavily illustrated, however they still manage to go into incredible detail.

    Corvette Buyers Guides and Corvette Coffee Table Books are some of the best places to find color pictures of a complete Corvette. While sometimes dismissed as simply eye candy with no substance, these can prove invaluable when trying to achieve a certain paint finish or determining the relationship between individual items within a subsystem. Curious if your heater hoses are routed the correct way or how your jacking instructions decal should be applied? These buyers guides and coffee table books are often a good start.

    Corvette Assembly Manuals are copies of the original instructions used by the factory workers while building the Corvette. Available for cars built from 1956 to 1982, these books are not very wordy, however they do contain detailed diagrams and drawings of the different assemblies. Black and white only and sometimes organized in an unexpected fashion, learning how to use the assembly manuals is a point of pride for many Corvette restorers. Remember, major sub-assemblies (engines, convertible top frames, seats and the like) were sent to the factory pre-assembled and are not covered as thoroughly. Available on CR-ROM or as a printed edition. If there is one reference that is considered essential for a restoration, it is the Assembly Manual.

    Repair and service manuals are typically split into two categories: Corvette Aftermarket Shop & Service Manuals such as Chiltons or Haynes guides, and GM Factory Shop & Service Manuals. The GM books would have been supplied to dealers and technicians directly and we are quite fortunate to have access to the diagnostics and specifications within. These are the references to use when your Corvette is having an issue such as running poorly, making a clunk-thud-clunk noise and so on. These manuals also have dis-assembly and re-assembly instructions for most of the major components, as well as electrical diagrams and flow charts. The aftermarket shop manuals have much of the same information, however it has been rearranged for the more casual mechanic. With black and white photos, easy to read directions, advice about common issues and more, the aftermarket books will usually answer questions not dealt with in the factory manuals.

    Whether you are a seasoned restorer, a grass-roots racer or simply an enthusiast, there is always something more to learn about your Corvette. With the help of a good book or two, no task is insurmountable. Many times it is best to check multiple sources, what is not in one book could be in another. It is not uncommon for enthusiasts to accumulate a small library just for Corvettes. But all of the study time easily pays off - the satisfaction from completing a job yourself cannot be calculated.

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  • How to Replace the Fuel Tank Sending Unit on a 1963-1974 Corvette

    Is your fuel dash gauge acting up? When it starts to register intermittently, fluctuate with its readings or just plain stops working, you can usually trace it back to the fuel tank sending unit.

    These units are always sitting in fuel. They are constantly moving and they are subjected to vibrations. That's why they are most often the cause for faulty readings on the dash gauge. The good news is that replacing a Corvette fuel tank sending unit is a relatively easy job that can be performed by anyone with a few good hand tools.

    Follow along with Zip's technical article "1963-1974 Fuel Tank Sending Unit Replacement" as we walk step-by-step through the replacement process on our Project 64. We've even included photos with each step.

    Before you start, there are some things you should keep in mind. Run as much fuel as you can out of the gas tank. It's much easier to drain 4 or 5 gallons of gas than 20. Always work in a well ventilated area and wear eye protection. You'll also want to gather a fuel drain pan, rubber fuel hose and clamps, emery cloth or sandpaper, hydraulic jack, jack stands and a shop manual for your car along with the basic hand tools.

    With those few tips in mind, you're ready to get started.

    For more great technical articles covering all Corvette generations, visit, your online source for Corvette know-how!

  • How To Put the Power Back in your C4 Corvette Power Windows


    Why are the power windows so slow on my 1984 Corvette?

    We get this question a lot. If you own a 1984-1986 C4 Corvette, you've probably noticed that your power windows are anything but powerful. "Painfully slow" might be a more accurate description.  Chevrolet didn't recognize the problem until mid-production in 1986 and then quickly fixed the flaw by introducing a second design window regulator.

    So what about those of you who are stuck with the less powerful and unreliable first design window regulators? There's an easy fix - and even better, it can be a do-it-yourself project!

    Upgrade your 1984-1986 ribbon-style Corvette window regulators with Zip's 1984-1996 Corvette Power Window Regulator and say goodbye to all of those annoying ribbon problems including broken ribbons, missing teeth or slow windows. You can also use this Corvette Part as a stock replacement for your 1987-1996 C4 Corvette to keep your windows working at their top performance.

    Fully assembled and ready for installation, the regulator includes instructions and all necessary installation hardware.

    Click here for Zip's step-by-step installation guide, including pictures!

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  • Things To Consider Before Starting Your New "Old" Corvette

    This Corvette question comes from Jo Ann who inherited a 1981 Corvette. I am inheriting my brother’s 1981 Corvette and it has been sitting in the driveway for over 5 years. It needs a lot of body work and a new passenger seat. The tires are slightly flat and are probably dry-rotted. We have not tried to start it up yet. Before we do, what advice can you give me before we try to start it up? This is one of the most commonly asked questions in the restoration hobby. The real answer depends on your intentions for the Corvette. However, whether you are looking to make it a nice driver or a show winner, these initial steps will help you start the car and determine what you have to work with. Al ... Continue reading

  • Corvette Wheel Offset & Back Spacing

    With so many different Corvette wheel designs on the market, finding the perfect set for your Corvette is not always as easy. At Zip, we take the guesswork out of the equation by listing the exact Corvette year a particular wheel set will fit. Of course this is assuming you Corvette has not been modified with aftermarket brake packages and/or body conversion kits. If your Corvette has been modified then you should be sure the wheels you are ordering are going to fit properly. To do so, you just need to understand wheel spacing terminology and use basic math skills. Let's go over how to measure your wheels.

    Wheel back Spacing is very simple and is often confused with the offset. To determine a wheel's offset you must first find the wheels back space. The back space can be measured in inches but should be converted to millimeters before proceeding to find the offset. To find the back space place a straight edge across the rear of the wheel and measure to the mount pad. The distance equals the wheels back space, which in this case is 6.75". Multiply the back space by 25.4 to convert the back space to mm (6.75" x 25.4mm = 171mm).

    Wheel offset is the distance between the centerline of the wheel to the wheel mount pad. It is measured in millimeters and the outcome can result in a zero, positive or negative measurement. To have a zero offset, the wheel mount pad must be even with the centerline of the wheel. A positive offset means that the mount pad is shifted past the centerline towards the face of the wheel, while a negative offset means the mount pad is shifted past the centerline towards the rear, or the brake side of the wheel. To determine the offset of a wheel you must first measure the overall width of the wheel. Lets say the wheel measurements are 18" x 9.5". Now convert the width to millimeters by multiplying the width by 25.4mm (9.5" x 25.4mm = 241mm). Next divide the wheel width by 2 to determine the wheels centerline (241mm/2 = 121mm). With the centerline and back spacing of the wheel determined and converted to millimeters simply subtract the centerline from the back spacing for the offset (171mm - 121mm = +50mm).

    Remember, we take into consideration every wheels backspace and offset before we offer a particular wheel for your Corvette. Each wheel set is listed for certain year applications because they are designed to fit properly to those models and are not guaranteed to work on Corvettes with modified body panels, suspension, brakes, etc.

    For more information on which Corvette wheels are right for you feel free to Contact Us today.

  • How To Remove & Reinstall The Starter On A 1972 Corvette?

    This weeks Corvette question comes from Ray who owns a 1972 C3 Corvette.

    How do I remove the starter from my 1972 Corvette?

    1968-1982 Corvette Starter Mount 68-82 Corvette Starter Mount

    The procedure for removing and installing the starter on a 1972 Corvette applies to all 1968-1982 Corvettes. It is not a difficult task to complete and only requires basic mechanical tools. To begin the removal first disconnect the battery cables (negative first) and raise the Corvette to an ideal working height. Next disconnect each wire at the solenoid terminals but be sure to reinstall the nuts after removing each wire as the thread sizes are different. If your Corvette has a big block, which included the starter solenoid shield you can now remove the front bracket upper bolt and remove the shield from the starter. For Corvettes equipped with the 350 engine you can now loosen the front bracket and remove the two mount bolts. You are now ready to remove the starter from the Corvette. After rotating the bracket away from your work space, lower the starter from the Corvette front first while holding it against the bellhousing.

    Once you are ready to reinstall your Corvette's Starter you can simply reverse the order of these instructions. Be sure to torque the mount bolts to 25-35 ft./lbs. first, followed by the starter brace bolt. Once correct operation of your Corvette's starter is confirmed the removal and installation is complete.

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  • How Do You Adjust The Windshield Wipers On A 1993 C4 Corvette?

    This week's Corvette question comes from Mike who owns a 1993 C4 Corvette.

    How do I adjust the windshield wipers on my 1993 Corvette?

    C4 Corvette Windshield Wipers C4 Corvette Windshield Wipers

    Despite their notoriety as a high-performance car and their innovations in design and technology, the C4 Corvettes had their fair share of imperfections. One common problem is with the C4 Corvette Windshield Wipers. Although only a minor flaw, the wipers on many of these Corvettes are not properly adjusted to rest beneath the hood when turned off. When the wipers do not park correctly, they can scrape the black paint on the window trim, resulting in unsightly scratch marks on the trim and blemishing the aesthetic appeal of the  vehicle. Fortunately, this minor problem can be easily corrected. All you need is a ratchet, 10mm socket, a flat-blade screwdriver, and no more than 20 minutes of your time. This simple adjustment will allow your Corvette's wipers to rest below the hood line and prevent your Corvette's window trim from being scratched again.

    C4 Corvette Wiper Access Plate & Grill C4 Corvette Wiper Access Plate

    After opening the hood of your Corvette, look in the direction of the wipers where you will see the wiper transmission access plate. Remove the plate with a flat-blade screwdriver by carefully prying up on it. Not all C4 Corvettes have this plate, if you don't simply remove the entire grill. Once the access plate or grill is removed you will have access to four retaining nuts. Loosen them with a 10mm socket but be sure not to remove them as reinstalling the nuts can be very difficult. Last, gently push the wiper arms towards the firewall. You will need to adjust both arms to avoid interference between them. Adjust the arms until they do not hit the windshield molding or they are below the hood line.

    Once you have your Corvette's windshield wipers adjusted properly you can tighten them down. Be sure not to over tighten or you could snap the stud on the linkage. Now check the adjustment. Close your Corvette's hood and have someone spray water on the windshield while you operate the wipers. (Don’t operate the wipers without water on the windshield or you could permanently scratch the glass). Make sure the wipers are no longer hitting the windshield molding. Switch the wipers to high to check that they are not contacting each other or binding up. If they are contacting, then readjust them until they no longer contact each other. The same applies if they are still hitting your Corvette's windshield molding. Once your adjustment is satisfactory, replace the access plate or grill and your job is done.

  • How Do You Remove The Radio From A 1972 Corvette?

    This weeks Corvette Question comes from Scott who owns a 1972 Corvette.

    How do you remove the original radio from a 1972 Corvette?

    The procedure for removing a 1972 Corvette Radio is the same for all 1968-1976 C3 Corvettes. You will need to start by removing your Corvette's RH Side Dash Pad. There are seven phillips screws that hold the dash pad in place; two in the door jamb, three on top where it connects to the top dash pad and the final two are on the side of the gauge console. Once the RH dash pad is removed you will gain access to the radio and gauge console.  Remove both radio side panels on the forward console, they sit under the radio and are held in with one screw. Once this is done, you will need to loosen the nuts on the bottom of the gauge console, they can be difficult to get to, but you should note that you will only have to loosen them not remove them. You can see these nuts by the radio side panels. After the nuts are loose, you can remove the two screws on the left side and then remove the upper screws that hold the wiper switch in place. Once all of the screws are removed, remove the radio knobs and the retaining nuts. The console will now pull out, but use caution because you still have wires and your oil line hooked up. If you can gain enough clearance to remove the radio leave these connected, if not then disconnect the wires and oil line and remove the console. The radio will now slide out so that you can disconnect the antenna cable and wiring harness.