Thread: Bonding Fiberglass to metal

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I need to know how to bond fiberglass to metal myself. my '67 Falcon had/ has 1 rotten out rear wheel well, nobody makes repo 1/4's for it, and a original will cost 3-600 from a place like desert valley or memory lane, so I got out some renyolds release tin foil, duct taped it neatly to my other side 1/4 panal ( is still in tact but marginilly rough ), got out some fiberglass putty and fiberglass cloth, carfully laid it over the tin foil, and puttied it up good, and let it dry, I now have a fiberglass patch panal ( reversed but it will work for a driver ) that I don't know how to attach, it lines up and fits ok, but I don't know how I should attach it, I was thinking scuff the metal mating surface and use my fiberglass putty over it, then stick it on and let it dry, but I want to make shure it will hold. ideas please? Thanks in advance.

Fiberglass and metal expand and contract at different rates....'Glassing up a whole is a fix usually associated with used car lots.... Why not shape some 20 ga. to the same contour of the wheel lip and weld it in. If you don't have a welder it would be worthwhile to borrow one or hire someone to weld it in. JMO

Matt, Anything you do will be temporary. The expansion rate for steel and fiberglass is quite different, so each day, as the car heats up and cools down, it can gradually delaminate.

Using a straight edge, like a yard stick, I would try to roll the edges of the hole inward 1/8th to 3/16th of an inch, tapered out to at least a couple inches or more from the edges of the hole.

Then I would grind your patch, and tape it to the backside of the hole. After that I would do several layers of mat over everything, and after it cures, grind it back to the original contour of the surface.

A good tip is to put a layer of plastic filler over the glass as soon as it has set up. This will cure the surface of the glass, and give excellent adhesion between the two. (They both use a polyester resin.) It will also be a little easier to grind this way.

I would agree with dave that it's better to repair in metal. That would be permanent.

Matt---about the best (cheap) way to do this, is use a coarse grit disc sander and take the paint completely off the area which you want to bond to. Cut a peice of mat (not woven cloth) slightly larger than the patch you have made----(about 1/2" larger all around), mix a small batch of resin and hardner, and use an old paint brush to cover the metal area with resin, lay the cloth onto the resin and "push" it into place with the paintbrush, then "paint" the inside of your patch with a bit more resin, then clamp the patch into place and leave it overnight.----Have all your clamps, etcetera ready to put in place before you mix the resin---you won't really have a whole lot of time to fumble around trying to get the clamps adjusted and placed, before the resin starts to "kick".----Your patch should extend about 2" beyond the rotted area onto good metal. Fair it in with body filler, and it will last 2 years to forever, depending on how much the tin-Gods like you.

In addition; If you insist on using the fiberglas patch make sure to use Epoxy resin rather than vinylester or polyester. It's the most expensive but is at least four times stronger bond.

Matt---I'm not sure what you mean by "fiberglass putty". Do you mean polyester bodyfill? For bonding purposes, liquid resin works better. Bodyfill will work too, but the bond is nowhere near as strong. Uncle Bob is right about epoxy resin being 4 times stronger, but methinks it costs about 4 times as much, too. You should be able to go to a NAPA dealer and buy a pint of resin and a small squeeze tube of liquid hardner.

Originally posted by brianrupnow
Matt---I'm not sure what you mean by "fiberglass putty". Do you mean polyester bodyfill? For bonding purposes, liquid resin works better. Bodyfill will work too, but the bond is nowhere near as strong. Uncle Bob is right about epoxy resin being 4 times stronger, but methinks it costs about 4 times as much, too. You should be able to go to a NAPA dealer and buy a pint of resin and a small squeeze tube of liquid hardner.

It is made by Bondo, it is called fiberglass repair putty resin, green compound, little thicker than conventional plastic filler, and uses the red cream as a hardener, which it then gets a milkey green color.

Hey Matt, I don't mean to sound like I'm putting you down for the cheap fix....I'm not. Here's some more words of wisdom from my Dad......If you don't have the time and money to do it right, how are you going to find the time and money to do it over???????

Just take your time and weld some pieces in, Those wheel lips been rusted for a long time, a waiting a little more time til you can do it right won't hurt a thing.

Just more advice from the "been there, done that" peoples !!!!!

Originally posted by Dave Severson
Fiberglass and metal expand and contract at different rates....'Glassing up a whole is a fix usually associated with used car lots.... Why not shape some 20 ga. to the same contour of the wheel lip and weld it in. If you don't have a welder it would be worthwhile to borrow one or hire someone to weld it in. JMO

it's not a hole, it's where the wheel lip is half rotted off, about center of the tire opening, the wheel lip is gone, I would use metal ( and I do have a Flux wire welder ) but I have no way of accuratly shaping the metal, which is why I made the patch, I'll eventully replace at least that 1/4 panal, but until I can afford to do that, I'd like the car to look ok, I'll probably touch up the area with some eggshell white, from a rattle can, should look ok until I can get 1/4's. hopefully, next year I will able to get the motor rebuilt and put a new 1/4 in, ( maby by then, they will be reproduced ).

Some flat steel and round tubing clamped in a vise works real good for forming tin. Get a couple body hammers and just keep playing with it til the shape is correct. Good practice and an excellent opportunity to learn some tin bending!!!!!!

Matt---I think what you have is a polyester resin bodyfiller with very short strands of fiberglass mixed into it. It is intended, as the name implies, to repair damaged fiberglass, as in fiberglass boats, snowmobiles, etcetera. It will work as a bonding agent, but it really doesn't give that strong a bond to steel.---if you want to use it for a bonding agent, take a 1/4" drill and drill a series of holes about 1 1/2" apart through the good metal, just beyond the rotted area. Take a tapered chisel of some type, put the end against each hole, and give it a light whack with a hammer, thus creating a small "funnel" shape at each hole. When you trowel on the "fiberglass putty" it will squeeze through the holes, and harden, forming a "key" to hold the patch and the rest of the filler on the outside in place.----This is a good "poor mans fix", used by penniless teenagers and unscrupulous used car dealers worldwide. I have fixed many of my own cars that way when I was young, and even fixed up the odd junker and sold them to poor unsuspecting fools in one of my previous lives

Originally posted by Dave Severson
Hey Matt, I don't mean to sound like I'm putting you down for the cheap fix....I'm not. Here's some more words of wisdom from my Dad......If you don't have the time and money to do it right, how are you going to find the time and money to do it over???????

Just take your time and weld some pieces in, Those wheel lips been rusted for a long time, a waiting a little more time til you can do it right won't hurt a thing.

Just more advice from the "been there, done that" peoples !!!!!

I know your not putting me down, you speak from experience, without this site and the knowlagble people in it, I would still be scratching my head, trying to put that 267 in my old '83 MB 240D. I just had the idea to use peices from a Mustang 1/4, rear wheel openings are the same size I think, I could use the wheel openings to patch them up, would it work? I know several places make '66-'68 Mustang 1/4's.

Originally posted by Dave Severson
Some flat steel and round tubing clamped in a vise works real good for forming tin. Get a couple body hammers and just keep playing with it til the shape is correct. Good practice and an excellent opportunity to learn some tin bending!!!!!!

I'v got the patch panal, I could sit it right in front of me, good visual as to what it is supposto look like, I could at least try. I'v got some metal I could use, I'll try it, if I can't get it to look right, I'v still got the patch

Sure, lots of wheel openings are the same contour as the Falcon.....sometimes you can even cut a piece out of a front fender and make it work. Make a cardboard template of the Falcon wheel opening, match it up with others til you find one that works...... If it's close, a bit of pinging and dinging with a body pick will make it right!!!!!!