Hood / Hinge fiberglass repair (C1 1957)

[Jean P.]

C1 1957

I need advise to repair the fiberglass of my hood.

The fiberglass where the hinge connect with the hood on one side is cracked and weak ... this connection is close to break ....

Any advise on how I should repair the fiberglass ? any repair kit exist.
Do I need to cut and rebuild the all piece ? just reinforce it ?

Should I use a different hinge ?
Any forum describe this issue ?

Tx

[Don H.]

Re: Hood / Hinge fiberglass repair (C1 1957)

Hello sir,
just want to say welcome to the club, and to this tech board.
I'm sure others who are knowledgeable will chime in soon with good suggestions on how to make the necessary repairs to your 57 hood.
Happy Thanksgiving!

[Jean P.]

Re: Hood / Hinge fiberglass repair (C1 1957)

Thanks for the welcome ! ... I have everything to learn ! : New car & new forum for me ...

Happy Thanksgiving.

[Chuck S.]

Re: Hood / Hinge fiberglass repair (C1 1957)

C1 1957

I need advise to repair the fiberglass of my hood.

The fiberglass where the hinge connect with the hood on one side is cracked and weak ... this connection is close to break ....

Any advise on how I should repair the fiberglass ? any repair kit exist.
Do I need to cut and rebuild the all piece ? just reinforce it ?

Should I use a different hinge ?
Any forum describe this issue ?

Tx

Hi Jean-Marc, welcome to NCRS Technical Discussion Board.

It appears the area has already had one unsuccessful repair. This is a high stress area, and it will require a high quality repair and gentle handling to not crack again. If you are a handy person and do most of your own home and vehicle repairs, you can probably do this job. If you hire others to do your maintenance chores, you probably will want to send this to a body repair shop.

You definitely want to keep the hinge. You definitely don't want to "CUT" on the hood. Before you begin this repair, you should have enough confidence in your skills to follow through to completion because an original C1 hood is pretty hard to find now. If you get in over your head, you can always take it to a body shop for repair.

To do this repair, you will need a 5" hand grinder, 36 grit and 80 grit grinding discs, 80 grit sand paper, sanding block(s), polyester resin, MEKP resin catalyst, fiberglass mat, coarse disposable paint (chip) brushes, an aluminum fiberglass roller, and acetone or lacquer thinner for clean up.

Remove the hood from the car, and place it upside down on a LARGE, PADDED work table. Remove the hinge and examine the area to determine what was done in the previous repair.

Ideally, the previous repair did not require the hinge mounting surface to be totally replaced, but only a surrounding crack repaired. If the mounting surface has been completely replaced, I would STOP. Replace the hood on the car, and take it to a professional body shop qualified to make fiberglass repairs.

If the mounting surface appears original, and only surrounding cracks were repaired before, then you can probably make a functional repair yourself. If you're a fast learner and take your time, you might even be a fiberglass expert before this is over.

I would start by looking for the new cracking...Is it in the previous repair or has cracked again outside of the repaired area? If the old repair is sound, I would leave it...If the crack is in the repair, then I would plan on removing as much of the old repair as possible back to virgin original fiberglass.

Begin GENTLY taper grinding along the new cracking, deeper at the crack, and fading shallower to nothing as you move away 3-4 cm. If the crack is in the old repair, gradually taper the old repair back to undisturbed virgin fiberglass. Once you have ALL of the cracking ground out, and the fiberglass tapered back to full thickness, you can begin your repair. It's important that ALL the crack be removed. You want this fiberglass to be all one piece when you're done; if you leave any of the crack, you leave weakess that can initiate future cracking.

Since I have just written a short story, and have previously posted volumes on fiberglass repair here, I will now allow you to do an archive search to continue.

On the top right of the TDB tool bar, you will see "Search"...click on "Search", then "Advanced Search", then enter "fiberglass repair" as the search phrase. If you like, enter my name and member number in the window for poster name. I just did it and found three pages of threads on various fiberglass repair threads...read it all if you want all the information you can get.

Good luck.

[Jean P.]

Re: Hood / Hinge fiberglass repair (C1 1957)

Thanks a lot very helpfull, it appear that the 2 cracks are in the already repaired section ... I think I will bring it to a specialist .... now the question is how do I find the best bodyshop expert in fiberglass in my area ? I'm North of Manahttan .... in NY state ... ?
Is their a list somewhere of the recommanded experts ?

Tx

[Jack H.]

Re: Hood / Hinge fiberglass repair (C1 1957)

I can't help with body shop recommendations in your area, but I can give you a bit of advice. A prime reason for fiberglass repairs not lasting (being durable) is the way the repair is done.

Just laying in bond and sanding smooth, WON'T work. You need to use real glass, hand blended with resin to get the desired strength. PLUS, some do the job 'quick & dirty' by laying down 1-3 layers of fill. That won't get it either...

The fill needs to be applied in MULTIPLE, THIN, layers being sucessively built up to approximate the density of the original glass panel. The pro's who make solid fiberglass repairs might wind up laying in 5-10 successive layers and that takes time & patience.

[Gary C.]

Re: Hood / Hinge fiberglass repair (C1 1957)

Jean-Marc,

Welcome to NCRS and the TDB forum. Special welcome to being a 56-7 owner.

Recommend you join the local Chapter nearest you. Chapter members will easily share their knowledge and experiences with you. Two NY Chapters are listed below

Looking forward to meeting you and seeing your '57.

Gary
....
Metro-Long Island Chapter
Bill Hermanek - Chairman
31 Wildwood Ln
Smithtown, NY 11787-3452
Phone: 6313601216
E-mail: bhermanek@aol.com
Web: www.metroli.org

Adirondack Chapter
John Dergosits - Chairman
863 Turnbull Road
Delanson, NY 12053
Phone: (518) 895-8402
E-mail: dergosits1@gmail.com
Web: www.AdirondackNCRS.com

[Chuck S.]

Re: Hood / Hinge fiberglass repair (C1 1957)

I can't help with body shop recommendations in your area, but I can give you a bit of advice. A prime reason for fiberglass repairs not lasting (being durable) is the way the repair is done.

Just laying in bond and sanding smooth, WON'T work. You need to use real glass, hand blended with resin to get the desired strength. PLUS, some do the job 'quick & dirty' by laying down 1-3 layers of fill. That won't get it either...

The fill needs to be applied in MULTIPLE, THIN, layers being sucessively built up to approximate the density of the original glass panel. The pro's who make solid fiberglass repairs might wind up laying in 5-10 successive layers and that takes time & patience.

Absolutely correct...and that's possibly one reason an old repair wouldn't last...it wasn't done right. I would use the phrase "resin and mat laminations" instead of "fill"...lest the reader think this is about bondo or filler.

But, to be honest, the original glass didn't last either or repair wouldn't have been necessary the first time. Done right, a repair should be just as strong as the original fiberglass...but, the highest stressed area will be right where the first crack appeared; the fact that it cracked again in the old repair is not too surprising.

The only way to reduce the likelihood of cracking there is to open and close that hood with kid gloves; use just enough force to engage the latches (good advice for all Corvettes C1-C6). I suspect this could be a common problem with C1 hoods. Guys familiar with metal bodied cars tend to drop or slam the hood from full open...bad idea for a Corvette.

[Joe E.]

Re: Hood / Hinge fiberglass repair (C1 1957)

I just finished a repair like this on a 56 that had been done wrong. The most important thing is to make sure that the height of the repair is to the origional surface so the hood will fit properly and not be to high to the fender height. The spread or location of the screw holes are important and need to be checked since this has been repaired before. I like to add a section of glass under the hinge plate and then use cloth and resin to build back to the origional height tapering it out well beond the repair area. This will require grinding away some of the origional surface in a tapering fit and there should be at lease five layers of cloth and resin when finished. Once a repair is done and dressed to the origional height and contour the repair should not be detectable.

[Chuck S.]

Re: Hood / Hinge fiberglass repair (C1 1957)

I just finished a repair like this on a 56 that had been done wrong. The most important thing is to make sure that the height of the repair is to the origional surface so the hood will fit properly and not be to high to the fender height. The spread or location of the screw holes are important and need to be checked since this has been repaired before. I like to add a section of glass under the hinge plate and then use cloth and resin to build back to the origional height tapering it out well beond the repair area. This will require grinding away some of the origional surface in a tapering fit and there should be at lease five layers of cloth and resin when finished. Once a repair is done and dressed to the origional height and contour the repair should not be detectable.

Thanks for the reminder, Joe...I was incorrect in saying "resin and fiberglass MAT" in my posts. The early Corvettes actually used a woven fiberglass cloth for reinforcement. Fiberglass cloth is actually much stronger than the random fiber mat.

The problem with fiberglass cloth was/is that the weave pattern was/is more difficult to conceal in the finished surface. So...If any you newby C2, C3 restorers are now thinking to use fiberglass cloth instead of mat because it's stronger and it will last longer...it will cause you deducts on C2s and C3s if it's visible.

[Brad H.]

Re: Hood / Hinge fiberglass repair (C1 1957)

Guys,
I know there are many articles on fiberglass issues, but I have one immediate question as my 69 is being painted as I speak. I had a crack across both "fins" (the vertical fiberglass sections coming down from the aft side of the top). Both the left and right fins have a horizontal crack or two across the fin about 4 inches from where the fins meet the top of the back body. There is evidence that there may have been a minor rear end hit, but all the other fiberglass is fine. I was hoping that when the tank was out the cracked area would be accessible from below so that cloth could be bonded up in behind the cracks but its not possible. The body shop which has been doing what I believe is a very nice job repaired this area by "v" cutting the cracks and using structural resin/glass mixture made by Evercoat I believe. I was hoping to somehow lay in a modelers fine fiberglass mat over the repair and blending it back in, but due to the location, that probably was not possible. I know some of you are experts in this field and I should have written before now, but anyone have any comments on the validity of the repair I just described?
I really appreciate any ideas!!!
Brad

[Chuck S.]

Re: Hood / Hinge fiberglass repair (C1 1957)

Guys,
I know there are many articles on fiberglass issues, but I have one immediate question as my 69 is being painted as I speak. I had a crack across both "fins" (the vertical fiberglass sections coming down from the aft side of the top). Both the left and right fins have a horizontal crack or two across the fin about 4 inches from where the fins meet the top of the back body. There is evidence that there may have been a minor rear end hit, but all the other fiberglass is fine. I was hoping that when the tank was out the cracked area would be accessible from below so that cloth could be bonded up in behind the cracks but its not possible. The body shop which has been doing what I believe is a very nice job repaired this area by "v" cutting the cracks and using structural resin/glass mixture made by Evercoat I believe. I was hoping to somehow lay in a modelers fine fiberglass mat over the repair and blending it back in, but due to the location, that probably was not possible. I know some of you are experts in this field and I should have written before now, but anyone have any comments on the validity of the repair I just described?
I really appreciate any ideas!!!
Brad

Yes...you should have posted before now. The preferred approach would be to have made the repair last spring, and then allowed it to bake in the hot summer sun if you were going to paint it this winter.

The repair should be made with a relatively wide taper ground area over the crack, followed with several laminations of resin saturated, rolled mat. You add layers until the repair is above the original contour, then grind and block sand it back flat. You could probably get inside the "sail" if you gutted the luggage compartment interior, but doing a proper taper grind inside there would be a trick...your own private version of hell.

I personally would not trust the fiberglass filled resin to last very long, but the painter is the one guaranteeing the repair (hopefully). Now might be a good time to find out exactly what his warranty covers if that crack opens back up in a year or so.

[Brad H.]

Re: Hood / Hinge fiberglass repair (C1 1957)

Thanks Chuck,
I really appreciate the info. After the repair was made and painted I felt it needed additional glass reinforcement. Oh well.... I have never seen another shark car sail crack across the V before. Any idea if this is a common weak point? If it is, it will definitely recrack in the future.
Thanks,
Brad Hoo

[Chuck S.]

Re: Hood / Hinge fiberglass repair (C1 1957)

I've never heard of that happening before, but my experience is limited. I suspect damage in that area from rear end collision is totally unheard of, but it would depend on the intensity of the collision and the direction of impact.

There are so many ways for the energy of a rear end collision to be absorbed. Fiberglass is like concrete in that it would be stronger in compression and less so in tension...it seems like something would have to hit the body from UNDERNEATH to crack the sail(s) horizontally.

For example, in a typical rear end collision, I would expect the tail light panel and rear spoiler/deck area to be totally destroyed and the energy to be absorbed into the rear fender panels to the point the bonding seams to the upper deck panel would be cracked...but not the sails. Any harder hit than that would get into the rear frame cross member, fuel tank, etc.

A hit hard enough to crack the sail(s) would surely have left some other evidence of collision repairs than just the tail light panel replacement; e.g., you should have seen repairs to the deck panel on the underside.

[Brooks G.]

Re: Hood / Hinge fiberglass repair (C1 1957)

Guys, I have been reading and watching this thread to see what methods folks are using to repair the hood area where the hinge attaches on '56 and '57 Corvettes. I own a 1956 and am well familiar with the problem as I had it with mine. I did not take pictures but will try to describe what was done to my hood to remedy the weakness in the are where the hinge attaches. First of all there is a metal plate inside the area where the hinge attaches which is drilled and tapped to hold the screws that hold the hood to the hinge. My hood was laid upside down on a table and holes were cut on the inside behind where the hinge attaches. Larger nut plates were installed in addition to the existing plates and held in place with screws. The remainder of the pocket was filled with fiberglass and bonding adhesive. The end result is a much stronger area where the hinge attaches to the hood. I guess that time will tell. I hope this will be of some help to you. I wish you all the best with your restoration. Brooks Glover (2141)