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Old 01-29-2006, 08:47 PM
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Removing "trim bump" ini 'glass fenders

Hi All,

I have a nice set of Fairlane 'glass front fenders for my '47 Ford coupe. The fenders have a "swoop" looking trim bump along the length of the fender that bulges out about 1/2". I'd like the fender to be "smooth" but have no idea how to remove it. There's no way it'll sand out. The only thing I can see is saw-cutting around it and clamping it flush, then reglassing it from behind.

TIA!

Russ
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Old 01-29-2006, 09:03 PM
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Easy to take care of. I am assuming that it has a reverse bulge on the inside. Saw that bugger off then back the back side up with some stiff cardboard covered with packaging tape. Mix up some polyester resin and some chopped fiberglass mat. Fill the hole with this mixture. After it kicks give it rough sanding to see if more needs to be added. If so add some more. Finish fill any minor voids with a skim coat of filler.

Vince
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Old 01-30-2006, 07:11 PM
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Vince,

Sounds easy! How many layers do you think it would take to build it to the same height, maybe 1/4" or so? I've not done much glassing, is this all done at one time or does each layer need to cure before the next is applied? And you say the backup "board" goes on the backside, seems logical (to a beginner) to put it on the front and get the smoother side out...

Thanks!

Russ
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Old 01-30-2006, 09:09 PM
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Probably five or six layers of glass mat will build up enough thickness. Yes, you would layer it up all at once. The cardboard with the packaging tape goes on the back to hold the glass mat and resin until it kicks. The packaging tape prevents the resin sticking to the cardboard.

I guess you could use something on the outside to kind of form the resin and mat to the shape of the fender. That would certainly cut down on the amount of sanding needed.

It sounds complicated, but it's really fairly easy. If you come by this weekend I can show you some glass work I did on my gas tank cover for my 34. I had to slice it width wise and extend it about 2 inches.

Vince

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Old 01-31-2006, 07:11 AM
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sand the area down good with 80 grit. lay a piece of cloth just above the body line for fill. then duraglass it after it cures . i have done it before but did'nt really like the outcome. just did'nt look right without the line.
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Old 01-31-2006, 07:56 AM
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Unless I have totally missed something here, I disagree with the plan. Cutting out a hole and filling it will almost always give you a "ghost line" later.

My plan, and I have done it (not with this exact application but simlar) would be to grind the back side of these humps a few inches around them and down into the valleys good. Be sure that every speck of them are cleaned up and ground. Then do the very same thing as mentioned with building up some glass, on the back side, filling the "valleys" up to make them level. Cut small strips of mat, wet the valley with resin and put the strips down into it, two or three making the strips little larger as you pile them on and using a throw away paint brush with it's bristles cut short to firm them up to push the air out.

After a few layers so you have the valleys completely filled, let it cure.

Now simply go to the out side of the fender and grind the raised portions flat! A coat of body filler over that to smooth it out and you are good to go.

Brian
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Old 01-31-2006, 07:59 AM
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"Basics of Basics" Fiberglass repair.
By Brian Martin

This "basics" is for a fiberglass repair where a piece is missing. It could be used even if the piece isn't missing, but just cracked badly. What you do is thin the cracked area very thin so you lay the mat over the top just as you would in the description below referring to a missing piece.

This is not a very difficult project. First you need to grind or sand with very course paper like 40 or 36 feathering the fiberglass out to thin it on the front and the back along the edge of the missing part. Don't thin it too much, at least not more than a half inch or so away from the missing part. At the edge you can go right down to a knife edge thin, but at about an inch or so you should let it remain pretty much the way it is. Taper it out to almost the original thickness within that inch. Just sand it down real good after that many more inches away on both inner and outer.

Next, cut your fiberglass MAT, not cloth but MAT. Fiberglass mat is the stuff that looks like it was shot out of a chopper gun with no particular patterns, just many many pieces of fiberglass strands laying over one another to form a "mat" of fiberglass. The cloth is the one that has all the fibers laying in perfect rows in a crisscross pattern. The cloth will ALWAYS show up later, the mat is basically the same as the car was made with so it works very well in patches.

You want to cut many pieces of this mat starting with a number like three or four that are very close the size of the missing part, even a little smaller. Then make a few that are a little bigger, then a little bigger then a little bigger. All of these should be in the area of an 1/8" to a 1/4" bigger than the last.

Next using 2" masking tape make yourself you "mold." Stick the tape on the back side across the missing area.

Now, mix up your fiberglass resin with hardener and using a little tray one of the smallest pieces of mat you have on the tray and pour a little resin on it. Using a short bristle brush "poke" at it with the ends of the bristles "pushing" the resin into the mat. You will see it become transparent when fully soaked with resin. At that point lay it down in the middle of the missing area. Then soak another piece and then another when the middle of the missing area is covered (you may not use all the small pieces you have cut) start going out with the larger pieces. You don't want the middle to be too thick or you will be grinding it all off later. So right as it is getting thick you move to the next size larger. All the while you are "poking" at the new pieces lightly with the ends of the bristles to push all the air out from between the pieces of mat, forcing in the resin. After you have covered the missing area and gone out some onto the feathered out existing fiberglass allow it to FULLY cure.

Fiberglass takes a long time to fully cure, sometimes hours. Give it time, if you start sanding on it all you will end up doing is peeling it up on the edges and it's adhesion will be compromised. After it is fully cured remove the tape from the back and lay some large pieces of resin soaked mat across the back of the repair going out on to the existing fiberglass a good couple of inches. It may not be too pretty back there, but it will usually not be seen anyway. If you wanted to you could smooth it off and even apply somebody filler over it and smooth it out real nice as well.

Once it is fully cured you can sand the outside to shape. When you cut into the mat you will likely have many small air bubbles and pin holes, not a problem. At this point you treat it like minor dent in metal, a coat of polyester body filler (bondo) should take care of it. I personally like to use Evercoats "Everglass" right over the repair and then a skim coat of "Glaze Coat" polyester putty to finish it off to perfection.

Tip 1: Get disposable latex gloves!! And it is advised to use throw away brushes and mixing containers. The small cost is well worth the savings in work.

Tip 2: Get cheap brushes and cut off the bristles about half way so they are stiffer.

Tip 3: Use NEW hardener. The hardener only has about a six months shelf life. Sure, it will last longer but six months is the "safe" shelf life, stick to it and you won't have a problem. Use an old one and find out how much fun it is to scrap off semi cured fiberglass (ask me how I know).

Tip 4: Use the gloves when sanding as well. If you can use a long sleeve shirt taped to the gloves and pulled up around your neck high. Wear a good particle mask! Fiberglass dust is very dangerous and irritating to the skin. After sanding go take a cool shower and just let the water run over you to wash it away before any scrubbing.

That is all there is to a fiberglass repair.
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Old 01-31-2006, 08:06 AM
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the raised part is part of your wheel opening. you cant just grind it off. i dont think your going to like it when done. i'm looking for a pic of a metal fender done this way. filling and blending from the outside is the simplest way to do it.
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Old 01-31-2006, 08:07 AM
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Here is the same concept at work. Remember, the fender is simply fiberglass strands like string that are cut up and sprayed into a mould with polyester resin. So if you add more mat which is exactly the same thing, with resin, you could build it up to a foot thick if you wanted, and it would be EXACTLY the same a foot thick as it would a quarter inch thick, same stuff thru and thru. Kinda like those counter tops they advertise that you can sand and polish out scratches because it is the same thing, all the way thru.

There are some epoxy resin parts that would need a little different technique but they are basically the same. I personally have never even ran into anything other than fiberglass working with car parts of all kinds and a zillion mobile home repairs I have done. But you should check it out good to be sure which technique to use.

“Basics of Basics” Fiberglass parts fitting.
By Brian Martin

You may not like this tip, at first glance is seems sorta hacky. But if you think about it, it is a quality way to do it. It was taught to me by the local Vette specialist.

The basic idea can be used with all fiberglass parts, as an example I will use a hood.

NOTE: Be sure your hood is fiberglass and not SMC. If it is smooth on the back side like a piece of stamped steel, it is likely SMC. If you find it to be SMC, all the same procedures in the following text apply EXCEPT, you need to apply a good epoxy primer over the SMC after you have done all your shaping on it BEFORE you apply any polyester fillers or primers.

You need to find the point on the edges of the hood that are the most "too high." Let's say that you have a decent fit but along the top of the fender it is too high at the front and too low everywhere else back to the rear where it is high again. You can’t “adjust” the middle of the low spot up, at least not with the hinges or latch. Align the hood as best you can with the high spots all being just above the adjacent panel. You want to sand the high spots down until you are happy that you have cut it as much as possible without jeopardizing the integrity by thinning it too much. What you are after is a “compromise” from the highest spots to the lowest spots. If you can cut the high spots enough to make the thing fit, great. If you can’t cut that much off, then you need to get it as close as you can so you don’t have to raise the low spots up as much. If the fiberglass is thick enough you can grind it down through the gel coat, don’t worry about it. A skim coat of polyester putty will fill pin holes in the glass. Then if you need to, align the hood again so that highest point is just shy of being perfect to the fender, just a tad low. Now shave the sides of the hood if needed until you have best gap. You do the same thing as the top. Find the widest point and shave it until you are happy that you have went as far as you can without cutting off too much. On some parts this may be an area you can cut a ton off without a problem. Other parts may not give you that option. If it had a lip that folded down, you don’t want to sand it off. You can “thin” the lip, but that is all. If you really needed to cut a lot off, you can of course re-make the lip. But this is not usually needed, the part wasn’t made THAT bad, or at least we hope not.

Do what ever it takes to get the panel as close to fitting as possible. If that means grinding mounting points thin, shimming, what ever it takes, do it now. This may include (and most likely, will) aligning the adjacent panels. Like any alignment of panels, it is not one panel, you are looking for fit between multiple panels so it takes alignment of all panels involved to make them fit well together.

Now, I have had fiberglass parts that were SO bad you couldn’t grind the high spots down enough without grinding through. In this case you need to build up the thickness of the part at these points so you can grind the top down enough. All it takes is to turn the part over on it’s back. Grind the area so that your resin and mat will stick and apply some there. When it cures, put the part back on and grind the high spot down as needed. If you need to grind all the way through the original glass to make it fit, so what, you now have made a “new” point where you can stop grinding by making the glass thicker. I have ground off mounting points to bring a part in closer and then made a new mount. Some of these aftermarket fiberglass parts are not very good, but if it is all that is available, you do what you have to do.

By the way, there is “Mat” and there is “Cloth”. Mat is fiberglass strands laying together in a random non-pattern and is usually thicker. Cloth is neat criss cross fiberglass strands. Mat will FILL much more. Cloth is used for structural support where strength is important. But I have to say, Mat more closely resembles how most fiberglass parts are made anyway, even structural points in them. Most all parts are made with a “chopper gun”. This is a “spray gun” that shoots resin and a “Spiderman” sort of web of fiberglass strand being chopped up as it comes out of the gun. It is sort of the “MIG welder” of fiberglass. There is a spool of fiberglass strand that it pulls from and then chops it up as it mixes with the resin and hits the surface of the mold to create the part. Mat is basically the same thing, the resin is just not there yet. On these points you need to thicken, the mat will do a fine job leaving all the structural integrity. How to use this mat and resin will have to be another “Basics”.

You will probably have a few areas that the gap is too big for your liking. You want to sand that edge with 80 grit so the gel coat is good and roughed up.

Now, sand the hood on top where it is low, sand REAL good out into the hood with 80 or even 40. I don't like to go out too far with the 36 because you are going to be feathering it out and you don't want to have those scratches to deal with. But if you know that it will be a way from the feathering area, 40 is better.

You should have the hood fitting as good as you can with the highest points on the top just shy of the top of the fenders and the edges so that the narrowest gap is "livable." The edges need to be sanded well and the top is ready for filler in the low areas and in from the edge maybe as much as a foot towards the center of the hood.

Now before you read on, think about this. The hood is fiberglass, right? It is polyester resin with fiberglass strands that give the resin strength, that is ALL it is. The gel coat is simply a polyester resin with some talc and pigment for color. So now that we have that straight, you are going to fill the low spots with Evercoats "Everglass," a fine cut fiberglass strand reinforced polyester filler.

Get some cardboard and stick it down into the gaps between the hood and the fenders. This is going to be your "levy" for the Everglass. Spread the Everglass on the hood up to this cardboard and press it down into any gaps between the cardboard and edge of the hood.

It will blow you away at how much you will fill with a coat of this stuff, if you don’t watch out you will be a quarter inch higher than the fender!

After the Everglass hardens, break out the cardboard and sand the Everglass flat to the tops of the fenders. On the edges do the same, “shaping” the panel is in your control.

Remember, you are only talking a little bit on the edges, so don't freak out thinking that you have "bondoed" the edge of the hood. It IS the same material, remember. In fact, if you ever sanded a fiberglass part good around the edges you many times will find that the gel coat is VERY thick. I have seen gel coat on the edges an eighth of an inch or more!

So just block the Everglass out, feathering it out onto the hood and get it a little low to the fenders. Now, skim coat the whole area with a polyester putty and finish sand it blocking with 120 or 180. When it comes to priming it, polyester primer is like re-gel coating it. It will fill pin holes and really is a great way to finish off fiberglass parts.


There is no reason why your fiberglass part shouldn't fit PERFECT. I just did a Pontiac Gran Prix "hot rod" hood with a bunch of scoops and things on it. It was very high cost hood and it fit like CRAP. I did exactly as I have outlined above. It is black, it looks absolutely beautiful and he blew away a his Gran Prix club buddies. Their car’s hoods look like crap now when he parks with them, the darn thing looks like a factory steel GM hood, maybe even fits better!

If you ever saw a Vette with perfect panel gaps, this is how they did it. You don't really think they fit that well from the factory did you?
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Old 01-31-2006, 09:06 AM
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The above process described by martinsr is what I did to even up the gaps of the ill fitting deck lid of my 34, worked great.

Vince
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Old 01-31-2006, 09:10 AM
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before you commit to this i would mix up some joint compound and smooth it out . then buzz bomb it black so you can see it finished. you also have the same line in the rear fender to deal with.
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Old 01-31-2006, 06:33 PM
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Whew! Information overload! Thanks for all the advice, I'm pretty sure it will look OK w/o the bump, but Shine's idea of joint compound is intriguing and simple enough to try...

Russ
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Old 01-31-2006, 10:47 PM
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Leave the line, in fact I would block it and perfect it so it is nice and sharp. These lines in my opinion add a whole lot more eye appeal to this body design. Nice sharp and straight lines also help to highlight the quality of the body and paintwork. JMO, Bob
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