How To Repair Holes In A Fiberglass Body

Fiberglass is a fickle mistress. While amazing things tin can be created using a piddling flake of resin and fiberglass strands, it remains in a abiding land of hardening. Sure, once the initial cure is completed, this process slows down significantly, over time the resin gets breakable. In the automotive environment, this means cracks, breaks and splits in the trunk of your Corvette. Add to that some of the more than "adventurous" owners of many of these cars, you may accept to repair fiberglass panels to get things back to normal. Take for instance the 1967 Corvette convertible we take hither. In the 1970s, this was a cool show car with a deep purple metallic bit pigment task and an 8-71 blower hanging out of the hood.

The motorcar had been sandblasted, which is a huge no-no for fiberglass, simply moreover, the glass itself was in crude shape. Lots of cracks and breaks that needed repair.

Surveying The Damage

Throughout this auto'south life, there accept been some bumps and scrapes which have caused some damage to the body. 1 of the worst was a split under the rear deck on the rear firewall betwixt the gas tank and the interior of the car. A previous owner had attempted a fiberglass repair, which nosotros were able to remove with just the twist of a screwdriver. This needed to be fixed the right way. We also wanted to repair the original stinger hood that had been modded with a giant hole for the blower.

Y'all tin can meet a large vertical crack in the torso. This needs to be repaired earlier moving on with the build of the motorcar, or information technology volition get worse.

The previous possessor had attempted a repair on the underside, only this just popped off with a screwdriver, non expert. Fiberglass is not an agglutinative; it but doesn't work that way.

Repairing A Fiberglass Crack

There are several factors that get into making a practiced fiberglass repair. The key is locking the new fabric to the one-time. While cleanliness is paramount, that is only one-half of the equation. Fifty-fifty with the surface clean and prepped, a mechanical bond is needed to secure the bodily repair. This is all-time done by drilling a series of holes around the perimeter of the repair to lock information technology in.

" data-medium-file="https://knowhow.napaonline.com/wp-content/uploads/2017/04/Vette_glass_03a.jpg" data-large-file="https://knowhow.napaonline.com/wp-content/uploads/2017/04/Vette_glass_03a.jpg" loading="lazy" class="wp-image-17114 size-full" src="https://knowhow.napaonline.com/wp-content/uploads/2017/04/Vette_glass_03a.jpg" alt="After cleaning the area with an 80-grit sanding pad on a die-grinder, a series of holes were drilled into the body on either side of the crack. These are ½" holes. It is also a good idea to drill the ends of the crack to stop its progress. The holes will connect both sides of the repair, locking it all in place." width="800" height="534" data-lazy-src="https://knowhow.napaonline.com/wp-content/uploads/2017/04/Vette_glass_03a.jpg?is-pending-load=1" srcset="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7">

After cleaning the area with an lxxx-grit sanding pad on a dice-grinder, a series of holes were drilled into the body on either side of the crack. These are ½" holes. It is also a good thought to drill the ends of the cleft to stop its progress. The holes volition connect both sides of the repair, locking it all in identify.

You don't need any special tools to mix fiberglass resin, but you do need to know how to mix it. Polyester resin is a ii-part substrate that when properly mixed yields a work fourth dimension of nearly 15 minutes. The hardener, MEKP (Methyl Ethyl Ketone Peroxide), is added in very pocket-size amounts compared to the resin base. Mixing minor batches typically means counting drops from a canteen. At that place is a proper ratio based on room temperature of 76 degrees. The mixture is exothermic, which means information technology puts off heat equally it cures. When the ambient temp rises or falls from that point, hardener is either reduced or added to ensure a proper cure. Too much hardener makes the resin breakable and it kicks too fast, non enough and it might not kick at all. Resin age is important equally well. Fiberglass resin (the base) has a shelf life of almost 6 months. It can be used beyond that, merely more hardener is required.

Mixing resin requires paying careful attention to the hardener ratio. If you lot don't accept a syringe, you lot can count the drops. 12 ounces of resin takes around 25 drops, and then you will be counting a lot and information technology is like shooting fish in a barrel to lose count.

Only mix what you lot can use in about 15 minutes. When left in the mixing cup, the exothermic nature will speed up the curing process, rendering your mix into a solid block very quickly. On the car, when information technology is spread out, this tin take an hour. A ratio of 2% hardener to resin is platonic, with 1% being a deadening cure for hot days and iii% being fast for cold days. Don't go outside of this ratio if you desire a quality repair. Measuring by weight, 100g of resin would need 1ml of hardener. If yous are mixing large amounts of resin, a syringe is advisable for measuring the hardener. For reference, ane teaspoon equals 5ml.

The blazon of fiberglass mat you need for your repair makes a divergence equally well. In that location are several types of matting bachelor, the near common being woven, chop mat, and loose fibers, all available in different weights. Chop mat, which has no blueprint, is just a serial of 1-2 inch long strands that have been pressed together into sheets. This is the strongest type of mat, but it does not lay down very smooth and information technology can come apart easily. This is adept for large, flat areas where strength is needed. Woven mat is splendid for a top layer over chop mat for a uniform finish and heavy curves. Loose strands are all-time for edifice up a bankroll surface area, filling voids and for mixing your ain reinforced body filler (think Duraglas®  or "kitty pilus"). For these repairs shown here, both woven and chop mat were used. The weights of the material have to practice with the intended use. For automotive body repairs, the typical mid-weight mats available in whatsoever NAPA Auto Parts Store are perfect. If you are building your own body panels, so you lot will want to exercise more research.

First, the trunk was treated to a base of operations glaze of resin. This serves to hold the mat in place.

Next, nosotros added a layer of chop mat.

The brush was used to push the resin into the mat. The mat will become transparent when it is fully wet. This was layered three times.

The process was repeated on the underside of the torso, completing the repair.

Repairing A Fiberglass Hole

Sometimes you need to fix a mod that was done by a previous owner. This stinger hood was modified and then a blower could stick out, only that is not the direction of this build. Rather than buy a new hood, we opted to ready information technology. Notation the holes have been drilled around the perimeter.

The acme side of the repair was taped off, and a slice of sheet metal was used to course the crest of the hood. We bent the metal in a brake to get a crisp line down the center. The underside of the metal was masked off likewise. The panel was taped to the hood.

We started with a layer of woven fiberglass to exist the superlative layer.

With the woven layer on, nosotros continues the process with chop mat, using a fiberglass docking roller to push out any trapped air bubbling. This adds a lot of strength to the repairs. We used about seven layers of mat for this repair.

The finish results of the repair matched the crest of the original hood, and the repair is fully locked in place and ready for finish piece of work.

Finishing

Finishing the repairs are simply similar any other fiberglass body work project. Sanding the repair smooth and then using a body filler and loftier-build primer to finish it. One extra step should be taken, which is to use a sprayable polyester primer. This seals the fiberglass much similar a gel coat for a factory-perfect cease.

The last stride after the bodywork is the polyester primer. This stuff goes on thick and is and then sanded off smooth. 3-iv medium moisture coats go the job done. This is over the filler piece of work we did on the hood, merely before the main body work to the remainder of the car. The polyester primer has to be block sanded.

After paint, the hood is perfect, you would never know that there used to be a giant hole in the center.

The process shown here can be used for whatever type of fiberglass structure, including boats, RVs and campers, even shelters. The key to a adept fiberglass repair is clean preparation, patience, and good quality components such as 3M resins and matting.

Check out all the paint & trunk productsavailable on NAPA Online or trust ane of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on how to repair fiberglass, chat with a knowledgeable expert at your local NAPA Motorcar PARTS store.

Jefferson Bryant View All

A life-long gearhead, Jefferson Bryant spends more time in the shop than anywhere else. His career began in the car audio industry as a store managing director, somewhen working his way into a position at Rockford Fosgate as a product designer. In 2003, he began writing tech articles for magazines, and has been working as an automotive journalist ever since. His piece of work has been featured in Car Craft, Hot Rod, Rod & Custom, Truckin', Mopar Musculus, and many more. Jefferson has too written 4 books and produced countless videos. Jefferson operates Red Dirt Rodz, his personal garage studio, where all of his magazine manufactures and tech videos are produced.

Source: https://knowhow.napaonline.com/how-to-repair-fiberglass-body-panels/

Posted by: mouserresichey.blogspot.com

Share this post