fiberglass hood plus

[evildky]

I was really wanting to do the one piece AZC fiberglass front end but after some searching I found the idea to be less then desirable and I don't care for the "boxed" flares either, so I am now thinking of making my own hood that will encoumpass the cowl panel as well as the access doors over the battery and master cylinder, and to then mould blank buckets to fiberglass fenders just to get rid of some of the many breaks in the bodypanels

 

I have very little experience with fibergalss but have seen some very impressive work done by people who learned as they built, so what's the best tips and tricks, and the best place to get large quantities of matt and epoxy? and or got a really good reason I should not try this?

[blueovalz]

I believe the cowl panel is restricted from any movement by the wiper mechanism? So to open the hood with an attached cowl panel, you would need to modify it in a way that would allow it to open with wipers in place (provided you intend to have wipers).

 

Aside from this obstacle, A cowl panel would not be that hard to fabricate, but could be complicated if you want to duplicate the vent slotting the OEM panel has. I've seen the underside of these panels, and provided you had a good, rust free, panel, I wonder if you couldn't us a release agent and simply use the underside of the cowl as a mold for your panel. Obviously the size will be slightly smaller doing this, but this would not be an overwhelming issue being this panel is of a thin gauge.

 

In 90% of my work, I've used a 2-ounce mat for fabricated parts and find this is a good compromise on a resin/mat (or cloth) ratio for strength and ease of fabriction. Materials for your project can be found at boat manufacturers or any other company that fabricates with fiberglass. You'll just have to look and ask around. I buy my mat by the roll (usually I see a roll were I purchase it) that's about half used up and buy the rest of the roll. Resin is expensive though, and for small projects, I buy the Home Depot variety, which is about 1/2 the cost of purchasing it out of a 55 gallon drum from my materials source. It's a little thick for my liking, but mix a small amount of acetone into the resin and it will thin out fast (which allows it to work into the the mat easier).

 

There is no good reason not to do this (if you've got some spare time and patience). For someone who has even the smallest aspiration to create custom fiberglass parts for his car, starting off on smaller pieces like this (or smaller still) is a great way to learn. And no price can be placed on experience and education, regardless of the discipline.

[Guest tony78_280z]

I don't think one layer of 2oz mat is going to stand up to wind resistant forces at high speed that a hood needs to withstand, will it? How many layers of 2oz mat would you suggest for a hood? After all, your the one who would know.

 

I too am contemplating this project, but I wont get started until the spring and weather is better. But by then I want to have my materials and my knowledge and plan ready to go.

 

This is the best site I have found. If you got a better one let me know. But they have some good FAQ and price lists and everything. I wouldn't buy their starter kit (buckets and gloves for $30.00) But the prices on the cloth (especialy in bulk) seem pretty good.

 

http://www.fibreglast.com/showproducts-category-Howto%20Guidelines-122.html

 

I am in the process of constructing a cowl. I've already made many mistakes and have learned the hard way. But that is why I choose such a small piece and one easy to remove and replace. (Besides mine was shot so whatever was an improvement.)

 

The technique I'm working on is I took the piece off the car (cowl in this case). I sprayed it with cooking release spray, like pam. Whiped off any puddles and then layed a layer of fiberglass ontop of it. (I used the realy flimsy stuff walmart sells, so next time I'll use something a bit stronger.) And waited for it to cure. When it cured I pulled it off washed off the cooking spray real good, and applied another layer to the back of the piece. It aquires the basic shape in that way. This wont make exact pieces or molds, but can help get close enough to the basic shape to modify and get a beter fit. Next time I'll use a stronger piece for my top piece and hopefully wont have to apply another piece to the backside where the spray is.

 

I plan to use the same technique (this spring) to make a hood, front fenders, and ZG like nose. But I just wonder how durable the cloth, or how many layers (of 2oz) of the cloth will I need to keep it from flying apart.

 

I see you have stolen my idea for making a fiberglass air cleaner holder. I plan to construct more of a cold air intake system Using fiberglass, aluminum 4" stove pipe, and 4" intake hose. Again though, I wait for the season to change.

[Sven]

Here's a tip for a release agent. At the ornamental fiberglass place I worked at in my teens we kept Johnson paste wax on a hot plate. We applied the melted wax to the molds with a 2" paintbrush. You then let it harden/cool before applying resin and mat (or going at it with "the gun"). It works quite well, and will save you the extra cleanup step with the Pam. I do like the use of kitchen products, though!

[Guest tony78_280z]

Do you not need to clean up/off the wax somehow? I would assume so. Tell us more about this procedure.

[blueovalz]

With resin, I count one layer of 2oz mat to equal about .040 - .050" (remember, this depends on if it's rolled out, and how much resin you want in it. On my panels, I used 4 layers, which measure out to about 3/16" roughly. The finer cloth or woven cloth takes a billion layers to get the same thickness, but will be more durable. Again, when I do this, it's a matter of compromise. I balance strength verses ease of construction. A higher resin ratio allows for better sanding and finish as well if you don't use the traditional gel-coat step with a mold.

[Guest tony78_280z]

So let me get this strait. You used 4 layers of 2oz fabric and that equaled about 3/16th inch in thickness. Before sanding I assume? And that was strong enough to withstand high speed wind resistance. I was thinking about using one layer of 7oz and then a layer of 2oz. Have you tried this? Do you think it'd be strong enough? It would cut down on cost, and production time with only two layers, even though one layer is slightly more expensive and would take more resin, it’d sure beat the addition two layers of 2oz.

 

I would figure a hood has a lot of force pulling on it because the front radiator inlet makes acts like a scoop and that air has no place to go. You have an outlet in your hood for the air, but I don't plan to put something like that in the front, I do plan to narrow my radiator intake hole, and add reversed (facing backwards, not sure what that is called) hood scoop at the cowl to let air out over my windshield. Hopefully that will relieve some of the stress but I don't want my hood flying all to pieces when I get up in speed.

 

Now that I have your attention though. I'd like to request you give out some good details on the procedures, materials, and tools you used to create that masterpiece. I've read your webpage and while it is inspiring and thought provoking ("Hmmm wonder if I can make something like this but only...") You really don't go into much detail about the how, how much, what kind and how much it all costs.

 

Myself and other striving Fiber Glassers would love to see a post (or webpage) detailing some of the processes and giving us some tips, tricks & techniques. Perhaps you could be some kind as to answer the following questions.

 

Where did you learn to Fiber Glass? A good book? If so what is the title? Some Fiber Glass school? Are you employed or have been employed in the FG industry? Trial and error?

 

How much in materials did it cost to fiberglass your Z? (Do not include paint please). I got my drill with attachments. My drimell (somewhere) and my ryobi hand sander (works GREAT for all kinds of body work) A cheap walmart brand auto body squeegee, and various plastic jugs for mixing.

 

What tools do you use? I learned today that metal files work real good on fiberglass =)

 

What materials do you use? You just said you used four layers of 2oz cloth and that you get it from the marine store (here in the Midwest we isn’t got boat shops =) The best place I got is the page I posted (above) on the net. And Wal-Mart. Are their prices comparable? Do you know of a better place on the net? What brand of resin do you use from home depot? And about how much is it?

 

What other tricks have you learned? You said that mixing acetone with the resin thins it out and allows it to absorb better into the fabric. I never would have thought of that! I have messed around a bit using the resin mixed with the bondo style fiberglass putty to make a thinner finer glaze like putty for a fine smooth coat. Unfortunately I didn't put enough hardener in it and it's taking for ever to dry. (Got it under the blow dryer right now =) Chalk another one up to trial and error.

 

How in detail did you do your back hatch? I want to do that too… but I don’t know how. I figure that will shave off an easy 30-40 pounds.

 

There is probably a hundred other questions I am forgetting to ask, and already I want you to write a book. I’m a car guy with considerable artistic talent, and fiber glassing is a very displayable art. It’s one of the most fun things I’ve tackled in awhile (and I’ve mastered many mediums) But I’m finding it hard to get solid answers to my questions and getting a foundation of knowledge to start my project.

 

Thanks

[blueovalz]

I've never used the 7oz mat, so I cannot address that. I do suspect the thicker mat will be harder to lay up over compound curves. Even the 2oz mat gives me some problems on smaller concave or convex shapes.

 

I have noticed that at high speed, my hood will deflect slightly in a downward position. Currently my hood rests about 1/4" above the water pulley. At triple digit speeds, this area of the hood compresses just enough to where the bolts holding the pulley begin cutting into the underside of the hood. Personally, I like the idea of positive pressure above the hood this far forward, but I was surprised by the level of pressure provided. The goal was to create a body suitable for racing (light weight) but not too fragile for street use later on.

 

I did not document the building of the bodywork 1) because I wasn't sure it would ever "work out" being it was my first "all body" work, 2) It was a divorce recovery project, and I wasn't in the mood to document anything in my life at that time. But I did finally (due to the many questions asked by so many folks) create a text document describing how and what I do with fiberglass. If you send me an Email (not a PM), I'll reply with is Word document attached. It's only my methods, and does not imply any professional process or results. The Word document is simply intended to answer the most popular questions I've received about working with fiberglass in a home garage without specialized equipment.

 

The lay-up on my car took a couple of days, but the finish work took years (but I kept changing things, adding here, removing there, etc) and cost (guessing here) about $600 in materials. I can't remember specifics on amounts of materials, but the higher quality resin will go further than the cheaper resin. Common sense, lots of patience, lots of thought about the design, and prodigious amounts of desire will insure a great finished project.

[Guest tony78_280z]

e-mail requesting the text doc is away.

 

It is advertised as 7oz cloth not mat. I'm not sure if there is a difference. I supose I will need to purchase a small amount and see how well it lays and bends.

 

Positive pressure is prolly better on a hood than negative in keeping everything together and tight. I hadn't thought of that.. How to design a hood in which area pushes down, instead of up?...

 

I know how divorces are. I wouldn't want to document anything either. Ya just try to get through them.

 

$600.00? I figured $200.00 for just the hood. Perhaps you had a cheaper supplier.

[ZROSSA]

Terry,

Thanks for the replys, I always learn something. You have the patience of a saint.

Tony, you can stop a lot of flexing buy adding local reinforcing. I have used cedar strips that you mold into the structure, also foam, carboard tube, any thing light that you can glas over the top of. This makes a tube like glass structure that is much more resistant to bending motions. Obviously you but this on the none visable side of your structure.

 

Douglas

[Guest tony78_280z]

Dang, cardboard tube... I wish I would have saved those Xmas wrapping papper tubes. So where would a guy get some cardboard tubes? I was planning on reinfocing with Fiberglass mat (thick stuff from walmart) but a tube does sound more structuraly stable... More complicated to assembel,.. but interesting. I was thinking about light wood molded into the structure.. but only as a last resort. Last thing I need is wood rotting away inside my car =)

[blueovalz]

Adding stiffness to a large, broad area, by added thickness to the panel will add excessive weight to the entire panel, which then acts against the added thickness (now the panel must support more weight). The most effective way to stiffen a broad area is well placed ribbing. I used 1" by 1" foam strips that were covered with a single layer of mat. The foam added no weight to the panel, and the "box" created over the foam greatly stiffens the edges of the panel (or anywhere it is placed). Angles can provide the same effect. In some areas I've simply bonded a single strip of 1" X 1/8" fiberglass strap, perpindicular (_I_) to the surface being reinforced. This works almost as well as the boxing.

[Guest tony78_280z]

1x1 inch foam strips of what? Styrofoam? I'm getting sculpting ideas from thinking about useing sheets of foam to get the shapes i'm looking for. Where did you aquire these strips? What is the best way to aquire sheets/blocks of foam? In sheets and then cut them? How much is a sheet. What is the best way to cut it? Sawzaw seems like overkill, but a knife could get tiresome. =)

 

I was thinking of adding fiberglass mat to high stress areas and around the edges for strengthening purposes. I like the foam idear better. It wouldn't rot, it may deteriorate a little but not decay.

[blueovalz]

I used two types of foam. The soft, crumbly foam (commonly used in "wet" floral arrangements and found at craft stores and usually green in color) is resistant to the effects of the resin (reacting or dissolving the foam for lack of a more accurate description) whilst the hard, crispy foam (found at same stores) will react to the resin, but is much more durable in its handling. If I use the later, I cover this foam with masking tape prior to covering it with resin to prevent it from dissolving away. Anyway, either foam cuts and sands extremely easily. These are the types I used to make the body panels on the BlueOvalZ (and all the other fiberglass parts on it).

 

Here is a photo of the hard, crispy type of foam I used in creating the tail light panel on my Z:

 

[Guest tony78_280z]

Interesting... very interesting.... Ever think of plastic wrap or aluminum foil instead of masking tape? Just an Idear.

 

And I see that piece you have there is a good size, I assume they come in larger sheets than that even. Do they come in blocks.

 

Did you include the cost of this foam in your original estimate you posted earlier? How much does this foam cost? How much did you need to do your car?

 

You said...

"If you send me an Email (not a PM), I'll reply with is Word document attached. It's only my methods, and does not imply any professional process or results. The Word document is simply intended to answer the most popular questions I've received about working with fiberglass in a home garage without specialized equipment."

Well I e-mailed you once from this website, and I will attempt your fototime site in a moment. Please send the document to Tony_78280z@yahoo.com

 

I'm gonna be out of town for the next 4-5 days so I wont be able to bug you with questions. But it'd be wonderful to find that text document in my mail box when I get back.

 

Thank Again

[Ferd/289]

There is a good book out that you can get from your library. The title is something like 'fabricating composites for race cars ', or something very similar. It covers the entire process including how to use FRP and carbon fiber and other materials. It covers how to design and make parts from simple to plug and buck based. I think reading this book will help you see the entire picture including the most important part ie how to form with the correct measurements. Sorry I dont remember the author, who I think was English, however there is only one pub that I have ever seen with this title.

Ferd

[Sven]

Tony, I've racked my brain, but I can't remember what we used to make the wax dissolve. Sorry, but its been over 10 years.

 

Ferd, is this the book you mean? Fiberglass & Composite Materials

 

I also found:

(click, then scroll down the page for two more) Fibreglast.com

[Ferd/289]

Sven,, thanks for sending this information so I could descrobe the right book. This is the book I had mentioned. It is very well done and comprehensive. It explains to the first timer, very clearly, and yet gives you the information you can use to make basic parts, and quite sophisticated parts, out of FRP and CF. I highly recommend it.

 

Competition Car Composites

By Simon McBeath, 2000, 208 Pages

An excellent guide for using composites in a home workshop. This book covers all the main materials and methods from wet lay-up to prepreg carbon fiber as well as core materials, resin systems and vacuum bagging. This book will appeal to anyone who builds, repairs or develops competition cars of components and to any motor sport enthusiast seeking a better understanding of composite materials and techniques.

[zliminator]

The lay-up on my car took a couple of days, but the finish work took years (but I kept changing things, adding here, removing there, etc) and cost (guessing here) about $600 in materials. I can't remember specifics on amounts of materials, but the higher quality resin will go further than the cheaper resin. Common sense, lots of patience, lots of thought about the design, and prodigious amounts of desire will insure a great finished project.

 

I learned a lot from the fibreglast website - they have a section with tutorial documents and I also bought the instructional videos. Get the one called "Step-by-Step Guide to Molding Fiberglass". The example uses epoxy and flanges, but start with polyester resin and stranded mat. My first project was a speaker enclosure from a plug. You will find the most of the work goes into getting the plug to take the correct shape and getting it to a glossy finish. I like to use sandable primer when I get close to the right shape. I apply several coats with a cup gun and then I start with the wet sanding and 800 sandpaper. Don't take shortcuts when sanding the plug. Use a single handheld light source in a dark room to check for humps and valleys. My current hood scope project is at this stage and I have a few pics on my website: http://www.hampleman.com/car.htm

[Guest tony78_280z]

Thanks for all the great info.. I'll need to check out/buy that book. Sounds great!

 

Man, this has been the most informative and intersting fiberglassing thread I've seen. Some one should make this sticky. Just to encourage that idea I'm gonna inluced Terry's text document he sent me right here. I hope he won't be mad at me for letting this infomation out =-) But this is too good to keep secret.

 

Terry of the famous BlueOvalZ wrote the following...

 

Fiberglass Technique

 

This write-up was originally posted at carolinazclub.com, BUT, that was just a temporary thing (car of the week, that lasted several months). The following is a copy of what I sent them.

Design: First I took pictures of the stock bodied Z, and then photocopied (black & white only). Then with these copies I began drawing various ideas I had about the bodywork (used pencil to match the black & white image). PhotoShop and other computer programs have also come in handy in viewing what my proposed modifications will look like before I even touch the car. Obviously, I gathered ideas that I felt were well tried such as Porsche, Ford GT, and various other “stealsâ€. After deciding on a final design, I went about duplicating this design in 3D.

 

Bodybuilding (we’re gon’na pump you up): The body was then done by hot gluing floral foam onto the metal parts of the body that I wanted to modify. There are two kinds of floral foam. A soft crumbly (will not dissolve in the presence of resin) that comes in 3†X 4†X 8†bricks plus some 12†X 2†X 36†sheets which is sometimes referred to as the “Dry†foam. Then there is the hard crispy (will dissolve in contact with resin) 2†X 12†X 36†type. I used the soft stuff at the time due to the large areas of coverage, their small size, and the fact that I was dealing with a lot of compound curves. This added the attachment to compound curves and irregular shapes of the stock sheet metal. Do not apply the hot glue to the parts or surfaces of the blocks that may need to be sanded to final shape. This is because the foam sands extremely easily, but the glue does not, thus you will have ridges and bumps everywhere that the glue is exposed from sanding. This is not really a big problem being this will only affect the inside of the body panel at this time. Anyway, after the blocks were glued on, I used an idiot stick with 36 grit paper and sanded to body to the final shape wanted. This is where a good visual sense to work in 3D from a 2D picture comes in. Sanding this foam will result in a fine dust that will irritate the respiratory tract somewhat, so you may want where a filter or mask. To maintain left to right symmetry, I only shaped one side of the car first, then cut out templates matching the shaped side, from corrugated cardboard. I made a vertical templates of the body panels for every foot of running length of the part being duplicated for the other side of the car, thus I had about 10 templates (not including the doors). Then I worked these templates carefully into the soft foam on the unshaped side of the car to the desired depth and then pulled them back out of the foam. Doing this thus leaves a slot or groove in the foam of which the depth of this slot matches the depth of the template, which in turn, matches the previously shaped side of the car. I then sanded this un-sanded foam down until the grooves (slots) left by the templates just began to disappear (be sure to repeatedly blow out the foam dust out of the groove to do this correctly. This way, both sides (fenders and quarter panels) were the same shape and size. Big point to remember is that when you do this and all other pieces, that the thickness of the fiberglass must be subtracted from the foam shape to get the final outside size of the final fiberglass pieces. In other words, I made all the foam pieces about 1/8†smaller all the way around, than needed because once the 1/8†layer of fiberglass is added onto the top of the foam, then the size of the piece will be correct. If you don’t take this into consideration, you will find all your parts to be slightly “oversizedâ€. Once the foam was the correct size and shape, I layered up about 4 layers of 2oz mat (total thickness of about 1/8â€). I did not use a fancy chopper gun, nore any specialized fiber glassing tools. In fact all I used was short knap paint rollers to squeeze out the air bubbles caught between layers. I did finally find a fiberglass roller (it’s an aluminum roller that has slots cut round it to squeeze air out of the mat as you roll it) that is very helpful with larger areas. Anyway, the lay-up of the entire body took one afternoon, and the sanding, finishing, and painting took 2 years.

TIP: learn about fiberglass with a book or two first, then make small parts like hood scoops, vents, etc first to get a knack for the temperature/hardener relationship, and then work up to bigger parts. The bigger the part, the harder it is to complete the lay-up of the part before the resin “kicksâ€. Once the entire parts are made, the hard work starts. To finish these parts, I used 36 grit on an air file (or idiot stick when the air file didn’t work) to knock down the irregular high spots. After the high spots were sanded down to match the low spots (laying glass smoothly was impossible, at least for me anyway), and then I swapped the paper to an 80 grit to get a better finish. From here on it was typical body finishing (filling in any bubbles opened up with the sanding process, etc). Once the bulk pieces where finished, I created the vents, and scoops, and the spoiler, and then attached or bonded them to the bulk pieces. On the hard (crispy) foam parts (smaller parts that are more flat) I would cover the foam with a single layer of 2†masking tape to provide an insulating layer between the resin and foam so that the resin would not dissolve the foam. This foam is very rigid and works well for specific applications where stiffness is required. Overlap the tape only a small amount, and rub the overlaps to make sure they are tightly sealed. When finished, the foam can be covered with the glass/resin without the buck being melted before the resin kicks. Once the resin kicks, the foam can be broken out or melted out (with lacquer thinner or acetone) and the part finished. On my Z, the hood, fenders, doors, quarter panels, and deck lid are all fiberglass. These were done as one piece, and then cut up (thus all the mating edges matched up very nicely) into the individual parts (quarter panel-door-fender). The air scoops, radiator opening, and vents were added after the main body was finished, as well as the underlying reinforcement to keep the parts from flexing too much. To make the deck lid and the side doors, I simply covered the steel parts with the 2†masking tape and a coating of WD-40 (to add the release of the fiberglass from the tape), and then covered this tape with the layers of glass. I have discovered that the glass will release from this tape fairly easily (even without the WD-40) IF you pull the part off the tape at a point when the glass is about 95% hard. It seems that the “bonding†stage of the glasswork is at the very end of the hardening process, so when the part is fairly hard and rigid, but not glassy hard, then this is the time to CAREFULLY pull it off the tape, making sure the part does not get bent while pulling it off. After you’ve done this “pull off†a couple of times with small parts, you will realize what the best “time†is to do it and gain a good feel for it on future parts. The reason I made these parts this way was because they are basically flat, and the 1/8†thickness of the glass does not “distort†the shape of these parts enough to cause concern.

Lastly, for parts like the air box behind the radiator used to shunt air out and over the top of the hood; I made this box out of 1/8†sheet fiberglass. This sheet glass was made by laying up glass onto a sheet of thick aluminum (1/8†will ensure a flat, un-curved surface). Once the glass hardens, then simply flex the aluminum (if thin enough) or pry the glass sheet off at one corner (on .125†aluminum plate), and you will find the rest of the glass sheet will pop right off. I’ve found that glass does not stick very well to aluminum, and again, if you apply a fine mist of WD-40 as a release, it will work even better. The oil will not affect the strength of the glass, but must be removed off the glass if this side of the part is to be bonded to another glass piece or painted. This is the process I use to assemble a series of flat parts cut out of flat glass sheet. It works quite well for many other purposes where a good smooth flat side is needed.

The hood modifications were not “ground up†creations like the rest of the body was. I started out with a fiberglass hood. Cut out the manufacturers reinforcement to suit my needs, and then started to reshape the hood. First, I still wanted some kind of power bulge in the hood that still in some way resembled the original Z hood, so I cut out the front half of the bulge off (this left quite a hole in the hood). Next, I cut out the opening for the radiator air to exit out of, which overlapped the previous hole already cut out. I then built a box for the radiator air to exit out of with 1/8†fiberglass sheet (made by laying 4 layers of glass on an 1/8†aluminum plate, letting it kick, and then popping it off before it set to a “hard†resin†(fiberglass will generally not stick very well to aluminum, and will readily pop off if done just prior to the hard, glassy stage of setting). Lastly, I re-attached (actually, I inserted it into a newly cut hole for this front part of the original power bulge to fit in, then glassed it into place) the previously cut out power bulge onto the rear of the hood so that it set over the V8 carburetor, just back of the transition where the normal hood surface starts curving downward toward the radiator. Bondo and sanded, and it was done. This is a very condensed explaination of what I did, but it will give you an idea of how I went about doing it.

Note added 12/1/01: To attach the bodywork after it was finished, I first had to remove all the steel parts that the new fiberglass parts would replace (with the exception of the quarter panels (in which the wheel opening was cut, lifted, re-weld, and left in place to maintain the unibody integrity and strength). Then I placed the fiberglass parts in the correct position on the car (using spacers and whatever came to mind to get a perfectly positioned part) and took note where the steel unibody came into close proximity to the fiberglass parts, keeping in mind the fact that at 100+ mph, much attention needed to be paid to optimal and well distributed points for better holding strength. To physically attach the body to the metal, I first had to create “pads†(again using the technique of laying up about 15 layers of strips which were 2†x 16†of 2oz mat onto a sheet of aluminum till set, and then cutting off 1†sections for each pad) of ½†fiberglass blocks (1†x 2â€) in which a 5/16†threaded hole was put through the middle of the pad, and then heli-coiled. Then this pad was bonded onto the inside of the body part in a pre-marked location (be sure to again scuff up the surface of each part with some 36 grit paper or wheel to ensure a permanent bond). Make sure to screw a bolt into the pad to keep the bonding agent (a single layer of mat soaked in resin between the pad and the part) from getting into the threads of the heli-coils. When this is set, then place the part back down on the chassis in the correct position, and bolt a metal tab onto the pad. These tabs that I used were .125†steel strips that were 1†wide, and of the appropriate length to go from the fiberglass part to the adjacent steel chassis part (keep them as short as is possible, as none of mine were over 2†long). Through trial and error you will bend and shape the tab to not only bolt onto the pad, but also have the other end of the tab rest next to (or on) the metal chassis in such a way that it can be welded (or at least tacked) into position at this time, knowing that the body will now fit correctly if indeed it is tightly bolted onto the tab (using short bolts of 5/8†or so because if you bottom out the bolt it could easily puncture the part or worst, separate the pad from the part). I repeated this step 10 times for the front cap. 2 behind the air dam down low, 2 in front corners of the hood up high, 2 midway back on either side of the hood, 2 on each side of the fender where it met the separate lower rear fender part, and then a few screws along the rear hood drip rail.

Terry

 

The following text is exerts from a forum dealing a member that was asking advice about the necessary modifications to match his hood scoop to his hood (it did not match the lines of the hood very well, with up to ½†gaps in places). This was a cowl induction scoop.

 

Your photos put your dilemma into better perspective. Let's try this. To begin with, I'd bolt this scoop on instead of bond it, but with the method I'll suggest, you will be able to do either. Being the scoop is so long, this causes the ends to be quite high off the curved hood's surface. My suggestion is (provided this is a glass scoop and not a plastic one) to cut or grind the bottom edge so that it more closely matches the contour of the hood all the way around the scoop (and remove any and all flanges that are on the outside edges of the scoop as you will not use these to bond the scoop onto the hood any more). Next rough up the surface around the scoop within 1" of the bottom of the scoop (especially on the inside edge) where it comes in contact with the hood using 36 grit or similar sandpaper, the rougher the better, to aid adherence to the fiberglass). Next, cover the hood with 2" masking tape (to protect the paint from stray resin, and the fiberglass part you are about to make), with a minimum of overlap (1/8" will be safe) between adjacent strips, then place the scoop on the taped hood where you plan to permanently locate it, and draw an outline (or footprint) of the scoop onto the taped hood with a Sharpie or something similar. Now, with the scoop removed, you now know exactly where the scoop will be placed because of this drawn outline. Next, cut out enough 2" wide strips of mat so that several layers of mat can be laid evenly along the inside edge of this outline. These pieces will be placed along the drawn outline or footprint so that about 1/2" of the mat will extend out past the outside of the drawn footprint, and the rest of the strip (1-1/2") will be on the inside of the drawn footprint. Thus you should have a 2" wide square-shaped "U" of mat resembling the outside shape of the scoop. Do all of this with dry mat as a trial run to make sure you have enough pieces to do this job and to make the total thickness of all the layers at least 1/8" thick. Thus with 2oz mat, you may only need 2-3 layers. With the cheaper, thinner mat, you may need 4-5 layers. Anyway, once you feel confident that you have enough strips of mat to do the job in one step, then clear everything off the taped hood, and mix up your resin (too much hardener will make it kick before you are finished, which is a big no-no). Before mixing the resin though, I'd suggest a light misting spray of WD-40 (if you don't have any mold release or wax around)

 

onto the tape to assist the release of the fiberglass you are about to lay on it. Now comes the messy part. These pieces need to be dipped into the resin to ensure they are fully saturated, but not so much so that resin is running everywhere. Lay out the soaked strips onto the hood just like you practiced with the dry strips earlier. WHILE THE RESIN soaked strips are still WET and in place, place the modified hood scoop directly onto the strip of wet fiberglass so that it lines up with the drawn outline (which will still be visible through the wet resin) so that only about 1/2" of the mat is showing all the way around the scoop, and the rest of it is hidden because it is under and inside of the edges of the scoop. Make sure every thing is set (making sure the scoop will not slide away from it's location on the sloped surface) and let the fiberglass "kick". The roughed up edges on the scoop will give the mat a good surface to stick to. After it is hard, gently remove the fiberglass you laid out (with the scoop now bonded to it) off the hood, The bottom of the scoop (flange) now perfectly matches the hood's contour. Next, reinforce the joint between the scoop and the newly made and attached glass "flange" that you made, by applying strips (2" wide or so) of soaked mat on the inside of the scoop all along the joint where the two meet (otherwise, the scoop may separate from this flange because it currently is only held together through the thickness of the scoop's edge that was modified (perhaps as little as an 1/8" at most) to further strengthen the bonding of the flange and the scoop. Now, sometimes this reinforcing will slightly distort the shape of flange that you made, so you may have to repeat the flange making process one more time and with only one layer this time, to ensure a perfect fit after final reinforcement has been done. Now, trim (sand) the 1/2" of material off the outside circumference of the scoop, and then you are ready to either bolt the scoop down as I did in the previously sent photos on the last string (using the inside part of the flange), or you can use this same flange to bond it on, your choice. Sorry for the long post, but I hope this better helps you understand what I was describing on the earlier post.

After another question, I answered:

 

Tomahawk's words ring true. I don't even want to talk about the time in my youth when I did fiberglass indoors (bad scene!). Anyway, use the chopped mat because the woven cloth will not hold as much resin, and in this case you want the additional resin because when you place the scoop onto the wet mat, it will slightly "crush" the mat, thus filling in the rough cut (gaps, uneven edges, etc) you made on the scoop to match the contour of the hood. With the colder temps, I'd first warm up the motor to full operating temperature. This will heat the hood, and thus warm the resin. I'd shut the motor off when you place the wet mat onto the hood, due to the chance that the vibrations could cause all this stuff to start sliding down the sloped hood. Big thing to note: The warm hood will be the difference between night and day on the cure rate at the temperatures you've mentioned. Also, keep the resin (autozone/home depot stuff will work fine) inside where it's warm before you start. If you feel you have the patience, mix a small amount with some resin, place it on the warm hood, and time when it starts to gel (starts getting thick and gooie), then gets kind of "waxy" (is somewhat solid, but crumbly), and then fully, glassy hard. For ideal conditions and based on your job, I'd not want it to start gelling until at least 20-30 min. Once it starts gelling, it's too late to work it, and if you're not finished, then you will need to start all over again from scratch on the fiberglass part. It will be fine if the gelling takes an hour or so. If it kicks too fast, put less catalyst in it, too long, add more, but a longer cure time will allow you to finish the job, were a too short a cure time is a royal PITA 'cause "I got’ta do this $#!t all over again" if I'm not completely finished once it does start to cure. Once fiberglass has reach the "waxy" stage (strands of glass will not pull out of the gel, but will break it apart), and you're happy with the job so far, then let it sit, carefully cover it with some plastic (don't move the scoop!!!), and then a blanket or something to insulate it and hold the heat in. The glass will create it's own heat on the reaction, so try to keep the heat held in. One good thing about slow cure rates is that the heat build-up is not so intense, and thus it will not distort the piece vs a fast cure on a hot day. If you still have time, then heat the motor up after the resin seems fairly hard, and give it one good cycle of heat to ensure it will be cured when you're ready to pull it off the hood. When you do pull it off, be patient, (work slowly from a corner first) if it wants to hold, and you will find puddy knife will come in handy at this point to help pry it off. Good luck and let us know how it turns out.

 

Let me add one more trick that I use when I make parts "on the car". This trick is one that I found accidentally, and works quite well IF, and its a big IF, you time it right. I've found that the bonding stage of the resin is at the very later stages of the hardening process. For example, once the resin gets that firm but crumbly stage, the adhesive bond that the resin has on the tape (or aluminum, paint, mold, etc) is only about 10% of what it will be with it fully hard and glassy. The bonding beyond this point starts improving quickly. So, with this said, my trick that I've used is to carefully test the waters (so the speak) of the resin's characteristics at the "firm but crumbly" stage. This can be done at a place where the resin was excessive and can be picked at with a pick or screwdriver to see how firm it is (it will be about like hard rubber), AND to see how well it separates from the tape. At a certain point, the resin will be firm enough to hold it's shape, but time wise, it's at a point before the "bonding" stage starts ramping up. At this junction, you can very easily and carefully lift the entire piece off the tape, and still have it hold its shape. Once the bond is separated, place the piece back down on the tape and let is cure completely. The piece will then lift off easily when hardening is completed. It may sound a bit tricky, but it works great in the absence of a good release agent. Good Luck.

With additional comments from others here, I feel this string could be a great archive for beginner fiber glassing. Please update this string with any photos on how your project came out. Oh yeah, the way I found out how this worked is I accidentally dribbled some resin onto the good paint not covered by tape. I found that instead of using a solvent to remove it, that if I waited till just the right time, the resin (firm but not hard) could be pulled off the paint in one whole piece, without marring the paint. Would not have believed it until I saw it.

 

After another member’s comment about some potential gaps between the metal hood and the fiberglass scoop prior to the aforementioned work.

 

It sounds like you've got a good grasp of what you need to do. The 1/16" gap is no problem. Like I said, the wet mat will crush and conform to the irregularities of the scoop's edging. In regards to the front point that was cut off? I would add enough mat just under this area so that it will fill in the small peaking gap in the center, and also jut forward a few inches. This way you will be able to shape it after it hardens to suit your needs (perhaps another point like it originally had). You will notice that once this scoop is removed that you will see a very slight scalloped surface on the bottom of the scoop where the tape on the hood was overlapped (from variations of tape thickness or steps from single thickness to double, or even triple thickness if you did that). This is not a real problem being the scalloping is only as thick as the tape is thick. But this is why I try to make overlapping minimal, or as an option, overlap 1/2 width each time so that the end result is 2 layers with a thin single layer groove instead of one layer for most of it with a narrow double layered ridge (yeah, it's kind of confusing explaining this in text). Anyway, it looks good. I'm holding my breath waiting to see the final result.

 

The member’s comment after doing this project:

 

Well it worked!!!!!! I did not have any wd-40 for mold release but PB Blaster worked VERY well. Just a little tug is all it took. I trimmed it up a bit and will do some sanding over the next few days. I still need to do something about the very tip of the center crease in the scoop. I most likly will build it up with 'glass and resin then sand it to a nice profile. I will be building the flange up from the backside just to make it stiffer and have some more body for the bolts to hold on to. I also think this will make the part much stronger. You guys have been so helpful with this project!!!! This is not my last 'glass project but I will not whine about the cost of a nice piece of 'glass next time I go to the swap meet!! Also a few things I learned along the way. 1) Rubber gloves are your friend. 2) cover everything with aluminum foil! 3) don't cut mat with your wife’s good scissors!! 4) four inch cut off wheels are great! Now all I have to do is prep it for paint and get this thing inspected.

 

My Last comment was about sealing the newly made scoop to the metal hood:

 

Auto body supply shops usually carry a sealant that comes in a roll that is a 1/8" or 1/4" bead that you unroll, lay where you want it, and then bolt the part on over it. It mashes down and seals the joint, and allows you to remove the scoop for what ever reason later on. Silicone will be pretty much permanent, so I'd suggest you not use it. Great job on the work, and as I see, you learned much about this work that I neglected to mention. You can do the front center tip the same way. Put down a small amount of tape for just the tip down on the hood, set scoop down on it, and add the glass just to that part. No need to do the whole hood for just a small part. Thanks for the pics. I attached my scoop by globbing on saturated mat onto specific areas above the flange you made, on the inside of the scoop. Then at these same locations, I drilled and tapped them out for Heli-coil inserts (after they were hard globs). Then I just installed bolts up through the hood and screwed them into the Heli-coils imbedded in the flange. You'd be surprised how well Heli-coils hold up in glass. I used 1/4" ones.