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Fiberglass repair question


TMA62
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I am about to start doing some body repair work. What products do you recommend? I have a few holes, a few surface ( seam ) cracks and a few complete cracks ( all the way through the fiberglass). I've never one this before so I am interested in your thoughts and advice.

Thanks in advance!

Ted

63R-1289 R-1

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My suggestion is to have someone who is very experienced with fiberglass repair do it. I understand the desire to save money and have the satisfaction of doing it yourself, but an Avanti is a tough car to learn on. It has nothing but compound curves that have to be massaged to get it correctly.

If you ask a body guy how it's done, he'll tell you that depending on the depth of the crack...and that you say the cracks are at body seams...the only correct way is to actually cut the affected area out and completely rebuild it or the crack will eventually reappear.

One thing before doing any repair is to determine the cause of why it cracked. From my personal experience with a '63 I once owned I suddenly found a crack at the peak of the front wheel arch at the seam. It turned out the body mount on the radiator support had broken and the flexing caused the crack. The repair to the radiator support was simple enough but any fiberglass repair would have cracked again if the cause wasn't identified and fixed.

You're certainly free to try the repairs yourself but be very careful and patient.

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I just finished the body repair on my 74 Avanti, so I have experience with the repairing but not the longevity. So here's what I did.

You need to vee out any cracks. If they are small and don't go all the way through, you need to get below the crack area to remove any stress risers,

If the cracks go all the way through, you still need to vee the surface and grind the the back side to receive glass fabric and resin. Cut the glass fiber to be much wider than the crack, spread catalyzed resin over the area and then apply the glass fiber and spread resin to fully wet the repair.

When the back side is done, fill and sand the vee'd side, the same way you would fill any crack. CAUTION!!!!!! Don't just use body filler, use Evercoat Vette adhesive/filler to fill the crack, It grips like grim death and sands pretty well. You can use regular fillers over that, I like the Evercoat Rage Gold fillers.

If you are bonding fiberglass panels together use West Systems six10 gel filler adhesive. I use it to bond the hog troughs to the bonding strips, works great.

A few more hints. Use Nitrile gloves to handle the resin. I went to our local restaurant supplier and bought a number of 16 oz plastic glasses for mixing, be sure they are not polystyrene ( cups will have a "6" and PS as the recycle code ) the resin will dissolve them. Use gloves and glasses when you grind, glass fibers itch like heck. Use disposable bristle brushes to spread the resin

And most importantly, any sanding needs to be done with a sanding block. Your hand will leave low areas. Remember, there is no metal to slow down the cutting action while sanding.

It's not rocket science but clean, roughened surfaces are necessary for quality work and there is no place for cheap substitutes on resin and fillers. Give it a try and ask more questions if necessary.

Bob

Edited by Avanti83
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I have not done any fiberglass repair so its nothing I would attempt. You are near Mike Baker's area, so I would seek his opinion regarding what needs to be done.

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Thanks guys for the replies. Actually, both of my Avanti's are over at Mike Baker's garage in Greenfield. I asked him the same questions. Not that I don't trust him. Afterall, I've entrusted him with my cars. Plus he might be reading this! ;-)

Seriously, I am very new to the hobby and I like to ask many questions to all people. It is a good way to get feedback and learn from other's experiences.

Mike and Rick Moon have done this work at the shop so I will have good supervision when I work on my car. Mike also mentioned Evercoat products. I know that Bondo Company has a fiberglass repair kit but I have never tried it.

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I have been using the Bondo Fiberglass resin on my Avanti's. As opposed to the fillers, most fiberglass resin is purchased from larger Chemical Companies and, I'll bet, there is very little difference between the resins sold. On the other hand, I do not like Bondo fillers and do not know of anyone that recommends them.

BTW, if all you were looking for was materials and a brief description, let us know next time and it will save me a long period of typing out unnecessary details.

Bob

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I had a guy with 30 years of fiberglass experience repair my '87 here in Indianapolis. I saw 8 cracks, he showed me 12 more. He did great work and was so reasonable it wasn't worth me doing it. Give me a call or come by my shop on the East side and I'll show you what he did with my Avanti.

Jim Wood

317-714-5269

fleetcare@ameritech.net

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I have been using the Bondo Fiberglass resin on my Avanti's. As opposed to the fillers, most fiberglass resin is purchased from larger Chemical Companies and, I'll bet, there is very little difference between the resins sold. On the other hand, I do not like Bondo fillers and do not know of anyone that recommends them.

BTW, if all you were looking for was materials and a brief description, let us know next time and it will save me a long period of typing out unnecessary details.

Bob

When my Avanti was repaired the fiber glass expect said that he had to get a specific type of resin for automotive use, he picked it up at an auto body shop and it had a car on the label.

Jim Wood

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When my Avanti was repaired the fiber glass expect said that he had to get a specific type of resin for automotive use, he picked it up at an auto body shop and it had a car on the label.

Jim Wood

Jim

Just for the record. This is the Bondo resin I have used for years. They claim that it is for all types of fiberglass construction including boats.

http://bondo.com/bon...-resin-404.html

IIRC though, the newer vettes and other vehicles are SMC (sheet molding compound) and should take a completely different resin.

If he uses a different resin, I'd be curious what he uses. It's never to late for me to learn new tricks.

Bob

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Evercoat and many over the counter resins have a wax in them. If you are building up layers it must be removed .(with lacquer thinner). Rub in one direction so as not to work it in, and use plenty of clean cloths to soak up the wax layer that skins over on fresh cured repairs. It's best to repair in single layers, let cure, wipe clean, sand to remove glaze (after cleaning) and repeat. Use collodial silica to thicken resins and prevent shrinkage . Use SMC adheasive as a top filler, it wont shrink.

After it really close, you can use regular glaze. Use paste white glaze in the can, not the softer 'pourable' stuff. Prime with a high build epoxy primer like PPG DPHS.

don't use polyester "Slick Sand, Slick Sand +4, or Feather Fill, you will regret it in the form of deep chips that form very easily.

Don't try to hide 80 grit scratches with primer. Finish your work with 220 then prime. Block your work straight with dry 320. Re-prime with a good 2K urethane block with 400 wet, then finish sand with 800.then you can base+ clear and not ever have to worry about your work showing through. Then you can have fun color sanding to 5000 grit in three successive stages, and buff so you can read your watch reflection from 10 feet away.

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Brad overall describes a first class paint job in a "nutshell".

If you want to learn more about auto body and decide to tackle it yourself, check out www.autobody101.com. Very good forum with knowledgeable people in the business plus many people like yourself. I have learned a ton! There is a dedicated area just for fiberglass work.

Edited by Paul K.
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