by John Pfanstiehl
The original style urethane bumper covers made their Corvette debut on the front of 1973 models. One important advantage of this type of cover is that it is so pliable that it can be stretched and pushed to conform to the common variations found in the dimensions of Corvette bodies. A urethane cover also is the choice to keep the car looking original or for judging purposes. The other side of originality is that the bumper cover will be somewhat wavy like the way they came from the factory. There’s also a good chance that the material will harden and eventually crack. If that’s a major concern, Zip Corvette also offers another option: the 73-74 TRUFLEX Front Bumper Cover which is made of fiberglass that will last as long as the rest of the body.
The steps in this urethane bumper cover replacement article are the same or similar when replacing covers on other years. And the different steps in installing a fiberglass cover are shown in the Zip Corvette Tech article 1973-1974 Corvette TRUFLEX Front Bumper Cover Installation which will be published in the future.
Follow along to see the steps for removing the old urethane bumper cover and installation of a new bumper cover.
01: After a dozen years on the car, a small crack appeared at the top center of the urethane bumper cover. That was the beginning of the end for this part.
02: Within a year, the side split wide open. Not a scratch or rub mark was on the paint, so this was not the result of a parking tap. Over the next few months, the cover cracked and separated in other places too.
03: If straight lines like these appear on the paint, the cover has already cracked under the paint.
04: Inspect the fit of the old bumper cover, or better yet photograph the fit at the fenders and upper panel. The fit is rarely perfect. It’s good to remember this when installing and adjusting the fit of the new cover.
05: Remove the grills with a Phillips screwdriver. If any of these screws are missing or damaged, Zip Corvette offers them in a set 1970-1974 Grill Mount Screws. More information on removal and installing of grills is shown in the Tech Article 1973-1979 Corvette Front Grill Replacement.
06: Remove the lower valance and note any differences in the fasteners. The front spoiler doesn’t have to be removed but it’s a good time to install a new 1973-1979 Stock Front Spoiler if the old one looks abused.
07: Note: the fasteners on the rear of the panel were machine screws but one was replaced with a sheet metal screw and clip. It’s not uncommon for these to be lost or changed. Zip Corvette offers a 1973-1979 Front Spoiler Bolt Kit.
08: Two nuts attach the bumper cover on each side and are relatively easy to access with a 3/8-inch socket on a ¼ -inch drive.
09: The upper outer nuts on each side are not visible but can be reached with a 3/8-inch socket on a short extension and ¼-inch ratchet.
10: A front cushion may have to be removed for access to the two upper center nuts.
11: This shows the position of the remaining three upper studs on each side. The headlight covers can be removed for access to the nuts from the top. I find it easier to leave the headlight bezels in place and remove the nuts from below. Plus there’s no risk of chipping the paint while removing the bezels.
12: Drill out the old rivets with a 3/16-inch bit to remove the old urethane bumper cover from its steel lower retainer. If the retainer is rusted or damaged, Zip Corvette offers a new 1973-1974 Front Bumper Cover Lower Retainer.
13: The old bumper cover broke into pieces upon removal. It turns out that the paint was the only thing holding it together.
14: The heavy steel front bumper impact bar is exposed when the cover is removed. A rubber bumper filler strip may still be attached. Zip Corvette offers a new 1973 -1974 Front Bumper Filler Strip and sometimes that can reduce the waviness of the cover. Zip Corvette also offers the 1973-1974 Front Bumper Lower Guard Fillers.
15: Inspect the rear of the old cover. These marks show that the steel bumper impact bar was pressed tightly against the back of the urethane undercover. Adjust the bumper bar and brackets if necessary so that it does not interfere with the fit of the new cover.
16: Don’t be alarmed that the urethane bumper cover is flexible as wet spaghetti. It will need the installation of the three retainers and the lower retainer to hold its shape. If the old retainers are rusty or bent, new retainers will make the installation much easier. Zip Corvette offers both sides 1973-1979 Front Bumper Cover Outer Retainer and the upper one, 1973-1974 Front Bumper Cover Upper Retainer.
17: Insert the steel lower retainer into the cover and pop rivet them together at the four countersunk holes. Use 3/16-inch rivets with a ½-inch or 5/8-inch head.
18: Trim the excess flashing from the edges of the new urethane bumper cover. Take your time and be careful not to mar the outer surfaces that will be visible when the cover is installed.
19: Tip: cement the heads of any retainer studs that are loose. If the studs spin in the retainer, tightening or loosening the nuts will be a problem. An epoxy like J-B Weld does a good job here.
20: Install the upper retainer first and then install the two outer retainers. Insert the two studs of the outer retainer through the bumper cover before tucking its ends under the cover’s flange. Installing the retainers may require a bit of wrestling.
21: Install the new 1973-1974 Front Bumper Cover, check its fit, and adjust it as necessary. A good place to start is aligning the center ridge on the bumper cover to the upper body panel.
22: Tip: spring clamps are a big help in holding the bumper cover to the car during fitting and installation if a helper isn’t available.
23: If the cover is higher or lower than the upper panel, some adjustment can be made by elongating the hole in the panel.
24: Tip: the useful amount of elongation is limited because the upper panel reinforcement is U shaped. The socket and nut can only go so far before hitting the lower or upper surface of the reinforcement. This limit can be checked by holding the socket and nut up to the hole.
25: Push on the cover to make sure there is some clearance with the steel impact bar on its upper and front surfaces. The cover can’t be fitted properly if the bar is pushing the cover up or out.
26: If either end of the impact bar is holding the cover out too far, its brace can be adjusted where it’s attached by 2 bolts to the frame horn. If the brace is damaged, Zip Corvette has new ones: 1973-1974 Corvette Front Bumper Outer Brace.
27: If the center of the bar is pressing on the cover, some adjustment can be made at its center mount. Usually this isn’t necessary.
28: Tip: the new bumper cover can be taken to the paint shop along with old pieces for color matching if it’s desired to not leave the car at the shop. The retainers should stay with the cover to hold its shape but fully mask the studs with tape or tubing to prevent paint build up on the threads.
29: After painting, install the urethane bumper and the replacement is complete. It can survive some minor dings without cracking and the car will look like it did when it left the factory.
1973-1974 Corvette Urethane Front Bumper Cover Replacement
Source: Zip Corvette Parts
8067 Fast Lane | Mechanicsville, VA 23111 | (800) 962-9632
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