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I though I saw an article recently either in the restorer or driveline regarding the correct way to replace a fiberglass panel, could someone refresh my memory?
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Re: C2 FIBERGLASS PANEL REPLACEMENT
I am sure there is more than one correct way. The main thing is to get the panel off without stressing the surrounding seams and panels.
If the paint is off the car you grind the panel off at the seams. I use a high speed disk grinder. You will be able to slowly rind through the panel and watch for a slight color change. In the majority of the cases you will have a detectable difference in color between the panel and the panel adheisive. Use plenty of light. I also have a shop vac that has a large clamp attached to the end of the hose. I clamp it near where I am working and suck the dust out of the air as I work. The vac has a very fine filter on it and I wear a respirator, always wear the respirator. Regardless, the dust will go everywhere.
If the paint is still on the car, I grind on the bad panel with a DA sander slowly untill I get down to the fiberglass and slowly work to where I know the seam is. I expose the entire seam. Then, grind the panel off.
Occassionally, I will use a stiff steel blade putty knife to seperate good panels. I drive it in between the two panels from the underside. Usually, I grind as much of the glue in the area away before attempting this. Luckly, most original panels were sort of put on poorly and they come apart fairly easy.
Hope you find your article. Just use the right tools and take your time. Grind only on what you can see, even in the tough places. I also cut way most of the original panel in the areas it is not bonded before I get started. When bonding the new panel, grind the two surfaces to bond with very coarse grit sand paper. You need to expose the laminate fibers. Wear vinyl throw away gloves and rub the adheisive onto the bonding surfaces. Test fit everything to death. I glue little pieces of fiberglass into the seam area to control the panel depth. I use large flat straps to clap the panels in place. Only use screws as a last resort to hold the panel in place. If you use screws, use very very small ones and plan on beveling them out and refilling them with either fiberglass and resin or panel adheisive. If you use original formula panel adheisive you can use that to fill the beveled out areas. Itchy job! Use heat lamps to cook the seams to avoid shrinkage. Good luck, Terry -
If you are planning on having the car judged....
I would not recommend screws. Evidence of there use always shows-up somehow.
Originally inside the panels at the bonding joints were prepped by sandblasting, just beyond the bonding area. I've judged restored cars that had the entire inside of the panel sandblasted and others with obviously overdone grinder rash.
H. a N. D.Comment
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Re: C2 FIBERGLASS PANEL REPLACEMENT
Terry,
Is the idea to leave the bonding strip in place to attach the new panel to? The panel I am thinking of replacing is the L rear quarter panel on a '66 roadster. Any recommendation on where to get a new panel as close to original specs as possible, color, texture, etc?Comment
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Re: If you are planning on having the car judged..
Although I don't plan on having it judged, I do want it to look "factory installed" Sounds like this might be over my head. I found a shop that specializes in this. I wanted to educate myself so I can ask them to show me how they do it, and be able to tell if I'll get the results I want.Comment
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Re: C2 FIBERGLASS PANEL REPLACEMENT
61 vette rear quarter panel replacement using no screws.....
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Re: C2 FIBERGLASS PANEL REPLACEMENT
Yes, there is a bonding strip on the underside that overlaps the bonding seam. It was very common to see the bonding seem on original cars after they were painted. This is because the adheisive wasn't given the time to shrink before it was painted. If you use heat lamps you will greatly reduce the chance of this happening. Only I would use the heat lamps about 1 week after the adheisive has set off by itself. If you force it to cure too fast it may not be good for the adheision process. The glue actually soaks into the panel the longer it takes to dry causing a better bond.
I don't believe that all cars got the same treatment when it came to body assembly. They pretty much slapped them together. It is very easy to improve on panel fit. But doing panel replacement is time consuming (expensive). It is hard to find people that really care about what they are doing. I new a place that use to use a TORCH to take panels off. They would burn the resin out of the area and pull the panel off by hand. They thought that was a smart way to do it. Interesting to say the least????
I think that if you are reasonably proficient with tools in your hands you can replace the panel yourself. My favorite tools for the job are the air compressor, high speed disk grinder, peumatic drill (with various grinding tips), DA sander, hammer and stiff blade putty knife and plenty of time and patience.
A screw hole is no different than any other repair that is done right. Problem is that people see it as a simple little hole that they can stick some bondo in or filler. That will give you problems right fast. It is best to drill in the bonding seam. Bevel the edges of the hole and uses bonding adheisive to fill the hole and the beveled out area. Shrinkage and differences in desity between the panel and panel adheisive are what cause problems. You have to shrink the seams or let the car sit a while (months) to let the adheisive shrink before you start to prep the surface for paint. If the adheive continues to shrink after you put the paint on the car, your eyes will go right to the repair.
I would avoid ever using regular fiberglass mat and resin to do a repair that is visable. 1) Too hard to get every little air bubble out (those little air bubbles are ticking time bombs under the finished paint) 2)It is impossible to get the same density in the repair as in the surrounding panel material that has been pressmolded (the more resin, the more shrinkage you will surely have). 3) If the repair is high in resin, it will be brittle, crack and fail. I would recommend you use original formula panel adheisive that is very close to the density of the original panel and is safe to use as a filler.
I use those cheap cargo straps you can buy at hardware stores and wrap them around the car to hold the panels in place. You need to get creative to get it done and you need to test fit it to death before you bond. Glue little blocks of fiberglass into the bonding area to control depth of the panel to the surrounding panel. Grind them down to make the two panels line up. It saves a lot of finishing work. It is good to leave a little glue under the panel anyways. You don't want to squeeze it all out which will weaken the bond. Some panel adheisives actually come will little glass spheres in them to prevent squeezing all the glue out.
Measurements help also. Even though the panel you are removing is damaged beyond repair you can usually get a lot of measurements form it. I use blue masking tape and tape it onto the area around the bad panel. I then use a makeshift plumb bob to find the begining of the wheel opening and end of the wheel opening. I mark the tape for these measurements. Measure both side of the car for comparison. You may have a chance to improve on things and it is not too difficult to make improvements from factory fit.
Another suggestion, use about 4 layers of tape on each side of the bonding seam (on the outside of the panel). The adheisive will squeeze out and you can use a plastic spatula to smooth it out. The tape will make clean up easier and make the repair look nicer. But most of all, it will cause the seam to stand up higher than the panel surface. You will find that it will prevent having to go back and refeather the seam with fillers. Its a lot of fun.
I am not an expert but this is what works for me. I have watched and talked to a lot of people about it. Good luck, TerryComment
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Re: C2 FIBERGLASS PANEL REPLACEMENT
I thought of one other thing. Before you take things apart, rehang the door on that side and make is perfect with regards to the front fender. Then make it perfect with regards to the top of the rear fender. Make sure it is where you want it then replace the quarter panel. You should be able to make the rear quarter meet the door edge perfectly. You may need to adjust the door a tad. There is give and take to be done but the results can be great. Above all else, do no harm. Good luck, Terry
Eckler's sells black press molded panels for your car. Shimmershine's does, and so does the Corvette Immage. Ecklers may be buying them from the later. I believe that Eckler's was advertising that they pressmolded them on original machinery. If that is the case, I would buy from them. The original molds were steel and had better uniformity of thickness. Thats all, TerryComment
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