by John Pfanstiehl
Corvette radios evolved with each generation. The C1 only had AM. AM/FM was introduced with the C2 and FM stereo with the C3. Their antennas evolved too. AM-only antennas were typically tall and telescoping. By the time C3s came along, a fixed antenna about 31-inches high sufficed. This more modest height sacrificed a little AM reception but was tuned for the FM range at a quarter of the wavelength of the average FM station broadcast frequency.
Over the years these antenna masts can lose their luster, becoming tarnished with surface corrosion. Fortunately, a new replacement mast is a relatively inexpensive part and can be installed in just a few minutes. If the chrome nut and spacer are also corroded, their replacement is a little more involved but is still a relatively easy task. Zip Corvette offers all these parts singularly or as kits.
Although this tech article shows antenna parts replacement on a C3, the steps are similar for many earlier and later models. Follow along to see replacement of the mast, chrome nut, spacer, gasket, ground plate and ground strap.
01: The old antenna mast lost its sparkle over the years. The replacement 1969-1977 Antenna Mast with Nut from Zip Corvette is an inch longer than this old mast (which may not be original). The mast and nut are stainless steel and has a 0.317-inch diameter chromed steel ball on its end.
02: Remove the mast nut with an open-end wrench while using a large adjustable wrench to prevent the big nut from turning. If only the antenna mast is being replaced, the task is nearly finished so skip to the end of this article.
03: The spacer under the large nut is a cast part and may be corroded like this. Zip Corvette offers a replacement 1969-1973 Antenna Nut Spacer. Replacing the large nut and spacer takes just a few more steps.
04: Zip Corvette also offers the 1969-1979 Antenna Nut and the plastic 1963-1978 Antenna Base Gasket. The gasket seals between the antenna nut spacer and the fiberglass. This gasket fits all 1963-78 Corvettes and can be used on 1979-1982 Corvettes equipped with a manual antenna.
05: Underneath the fiberglass is a thin aluminum ground plate that provides a ground plane for the antenna. This part is not necessary on metal cars because their body panels work as the ground plane.
06: If the ground plate is missing or in need of replacement, Zip Corvette offers the 1969-1973 Antenna Ground Plate which comes with its 4 rubber bumpers and reinforcement for the antenna end. A small screw, lock washer and nut are needed to connect the ground strap to the reinforcement.
07: Note that the 1974-77 ground plate is shorter. This Corvette was a very late production 1973 so that may explain why it had the later model ground plate. Zip Corvette also offers the 1974-1977 Antenna Groundplate and it’s made in the USA.
08: Zip Corvette offers the brass 1963-1977 Antenna Ground Strap, too. This reproduction strap is made in the USA. Offered separately to attach the strap to the frame rail is the 1963-1977 Antenna Ground Strap Hardware. It is the original style and includes an indented hex head thread cutting screw and external tooth washer. It’s also made in the USA.
09: The left muffler was unbolted at the muffler hanger and lowered to make easier access to the ground plate and antenna cable end. This step is not necessarily essential if you’re able to reach up around the muffler.
10: The spacer is keyed to be aligned with the notch in the body. If the spacer was not aligned, the antenna would stand at an unsightly angle to the body.
11: The spacer is a cast part and is likely to corrode, pit and bubble over time. The mast and its nut are stainless steel but they can dull over time, too. Zip Corvette offers a new 1974-1977 Antenna Nut Spacer, shown here next to the old spacer.
12: Tip: test the replacement nut on cable to make sure it screws on easily. Also lightly grease the threads. This nut is just a bit larger than 1-1/8 inch. That size wrench or socket may or may not fit but a large adjustable wrench works fine.
13: The antenna cable end has projections that fit into notched tabs on the ground plate reinforcement. The tabs may need to be bent slightly to fit. Hold the cable end and plate up against the body while installing the nut on top. Although it’s helpful to have an assistant, a long-armed person can install the nut by themselves.
14: Bolt the ground strap to the frame rail. Note there may also be a ground wire from the rear harness for the lights. Check the rear lights afterward to make sure their ground is good.
15: The replacement ground plate is installed. Depending on the bonding strips or amount of excess bonding material, the plate’s outer edge may need to be bent down. The thin aluminum bends easily. Make sure the plate’s upper surface is relatively flat and not curved upward.
16: Lightly grease the portion of the mast that slides down into the cable end. That ensures the mast can be easily removed later. The grease won’t diminish reception.
17: Check to make sure the antenna mast is straight up – not on an angle. Tip: sight the mast along the vertical wall of a building. If the mast is angled a little, rotate the mast inside the cable end to achieve the best alignment.
18: The replacement antenna parts now sparkle like new.
1969-1977 Corvette Antenna Replacement
Source: Zip Corvette Parts
8067 Fast Lane | Mechanicsville, VA 23111 | (800) 962-9632
Corvette Parts List Related to Article:
- 1969-1977 Antenna Mast with Nut
- 1969-1973 Antenna Nut Spacer
- 1969-1979 Antenna Nut
- 1963-1978 Antenna Base Gasket
- 1969-1973 Antenna Ground Plate
- 1974-1977 Antenna Ground Plate
- 1963-1977 Antenna Ground Strap
- 1963-1977 Antenna Ground Strap Hardware
- 1974-1977 Antenna Nut Spacer
- 1978 Antenna Nut Spacer
- Shop & Service Manuals
what do you do when the mast is frozen and wont come out
Had the same problem. I sprayed PB Blaster on the nut and base of the antenna. Next day I was able to use a pair of vice grips on the base of the antenna shaft and loosen it up, and voila it was out.