A sound that a Corvette owner never wants to hear is a siren wailing from behind. Another is the sickening sound of crunching fiberglass. And the latter is likely to be even more painful than the former. Follow along to see what is involved in minor fiberglass repair and gain tips on handling these and other collision repairs.
C1 Corvettes are composed of fiberglass body panels that are bonded together, creating many finished seams that hopefully are not visible. A person can run their finger along the paint from the front of the car down the front fender, along the rocker panel, up the rear fender, over the back and down the other side to the front again without feeling a seam. This makes a very smooth-looking body but also makes for a lot of work when a body panel has to be replaced. All the seams where the panels abut have to be ground, sanded and finished to a high standard in order not to be seen.
Another problem with this type of fiberglass body construction is that there is no end to some of the individual body panels where repainting can be stopped. This issue is of particular concern with cars that have a clearcoat. When a painter blends the clearcoat mid-panel, the layer of clear being applied gets thinner and thinner. A thinning clearcoat edge doesn’t hold up well to the elements and is often not an accepted repair procedure.
C2s and C3s changed to bolt-on rocker panels making replacement and repair of some body panels a bit easier. However, the fenders were still bonded to the upper surround (top) panels. Replacement of any of these panels requires grinding and chiseling to separate each from the adjacent panel. After a new panel is installed and bonded, the bonding material exposed at the seam still needs to be ground flush to the panel surface and properly finished.
An ever-present problem is that bonding materials and body fillers tend to shrink with time, even ones that are catalyzed. A fiberglass repair may look perfect when leaving the shop but months later subtle lines give witness to the fiberglass repairs when looking closely at the paint. For that reason, it is essential that you find a shop that has plenty of experience repairing the earlier Corvette fiberglass bodies.
The primers, sealers, color coat (basecoat) and clearcoat can also shrink. This is less of a problem with modern two component (2k) catalyzed paints than it was with lacquer paints. The shop I worked at years ago, Corvette Center in Connecticut, used to reassemble the lights and bumpers on a freshly lacquer painted car so that the owner could drive it for a few months to allow the materials to stabilize before it was brought back for wet sanding and buffing. (Unsurprisingly, more than a few of these cars sustained collision damage again during that three-month waiting period. Their 6.70x15 and 7.75x15 tires were no match for a Corvette’s horsepower back then.)
Even with today’s improved bonding and filling materials it is always wise to give them plenty of time to fully cure before the final paint is applied. Heating the repaired area with infrared lights or parking the car outside under the sun on a warm day helps accelerate the curing process and thereby reduces the amount of shrinkage in the following months.
Fortunately, owners of later-generations of Corvettes have little or no worries about the hidden seams and shrinkage where panels are bonded together. C7s, for example, are designed so that the individual body panels abut one another with no finished seams. That enables body panels to be individually replaced, repaired or repainted. Because of this, when panels are replaced as opposed to repaired it is not as essential that repair shops have a depth of experience working on early Corvettes. Still, if fiberglass repairs are needed, it is always good to see other Corvettes in the shop and be able to inspect the shop’s work on our prized plastic possessions. Vette
1. The scene of the accident. The short guard poles were not visible as the car turned right around a large tree into a slanted parking space. Multiple colors on the pole show this wasn’t the first time it bit a car.
2. You can often reduce the cost of repairs by doing some disassembly yourself. The owner removed the grilles, parking lights, sidelights and emblems before it was brought to the shop.
3. Inspect the body and paint on nearby panels to determine if there are other defects or damage to repair. It will cost a lot less to take care of these at the same time. Also, painting adjacent panels can help with color matching. The small crack in the fiberglass on the driver-side fender could be fixed and the misalignment between the body and the urethane bumper cover could be improved.
4. Although not easy to see, there are several small bubbles on the hood. These might have been caused by oil absorbed into the fiberglass. As a recent Vette article showed, it can be quite a process to making sure paint problems from oil contamination in the fiberglass don’t return.
5. Here’s the car as delivered to Superior Auto Body in St. Petersburg, Florida (the bumper cover was removed by the owner). An old bumper cover or its paint can crack upon removal or handling so don’t be surprised if the shop warns you of that or asks that you remove the cover yourself.
6. Superior Auto Body owner Ron Valario is doing the initial grinding around the cracked fiberglass to determine the extent of the damage and to determine what lies under the paint.
7. The 36-grit grinding disc makes fast work of removing the layers of paint and exposing what lies beneath. Tip: when doing any heavy grinding of fiberglass, tape your sleeves closed or you may have a serious case of the itchies hours later.
8. Like a box of chocolates, you never know what you’re gonna find underneath paint. From the left you can see the most recent red paintjob, a prior red paintjob, a skim coat of body filler, a glass mat from a prior repair, and finally the gray of the factory fiberglass panel. Near the top of the ground area, the seam where the fender was bonded to the upper surround panel is visible.
9. The exposed layers of different materials at the driver-side front corner told a similar tale of prior repairs once the layers of paint were removed.
10. On C3 Corvettes, the front fenders are connected to the upper (hood) surround panel by bonding strips that lie behind these body panels and are glued together. The narrow gap between the panels then has to be filled, sanded and finished so that it is invisible when painted.
11. Both woven fiberglass cloth and non-woven fiberglass mat were used in this small repair. The woven cloth was laid down first to provide structural strength. Then the randomly oriented strands of the mat reinforced the subsequent layers and filled areas. The mat-reinforced resin is easier to sand and is effective at hiding the print-through effect that can result from using only heavy fiberglass cloths.
12. In the final layer of fiberglass that was applied, the random fiberglass hairs are barely visible through the red-tinted resin. The repaired area is made significantly larger to ensure a smooth transition from the damaged area.
13. Inside the fenderwell, the adjoining surfaces were ground and bonded together to provide additional strength to the repair. The bonding strip that connects the fender to the upper panel can be seen with the old glue that seeped out from its lower edge.
14. The front side of the front fenderwell panel was also bonded to the fender for added strength.
15. A number of body repair materials are used for the finish work. Evercoat Edge long strand is reinforced with Kevlar and other short and long strand fibers. 3M Platinum Select filler and Evercoat Edge premium putty complete the job prior to painting.
16. The body filler materials are applied over the fiberglass on the left side and are ready for block sanding.
17. Greg Cacace is using a long board to smooth the surfaces prior to paint. Greg’s previous employment working on high-end fiberglass boats provided useful experience for fiberglass repairs on Corvettes.
18. Because bodywork was done to the front surface of the fender, it is essential to mate it again with the bumper cover to see if there are high or low areas that prevent a good fit.
19. After the fenders are modified to fit the bumper cover, the first coat of primer is applied. It is very important to thoroughly mask adjoining areas to prevent overspray from getting onto the fenderwells and into the engine compartment. Removing overspray is a job you really want to avoid.
20. The waterborne basecoat looks drab and dull without the clearcoat. Superior elected to paint the entire front end to eliminate color match problems with the hood and headlight covers. Be forewarned: reds and yellows are among the most expensive auto paint colors.
21. The waterborne basecoat looks drab and dull without the clearcoat. Superior elected to paint the entire front end to eliminate color match problems with the hood and headlight covers. Be forewarned: reds and yellows are among the most expensive auto paint colors.
22. Reassembly was easy and the fender is much better than before. This is a good time to replace tired trim parts, emblems, light housings and grilles because now it actually looks better than new.
23. Rick Tousley’s C7 shows how Corvette body panels have changed over the generations. The rear fender is separate from the deck lid and rear bumper cover. The horizontal seam where it abuts the rocker panel is also just visible. Replacing and repairing panels on later-model Corvettes requires much less bodywork and refinishing.
24. One-piece fiberglass front ends enable you to avoid assembling, aligning and gluing together all the front body panels. They also eliminate the problem of shrinking seams. This C3 front end is available from J&D Corvette in Bellflower, California.
25. It is always comforting to see other Corvettes at the body shop facility you choose, but it’s particularly important with the special fiberglass repair needs of C1-C3 Corvettes.
Photos by John Pfanstiehl