Cheap and easy fiberglass hood

So, we have a challenge car that is going to be damn near over budget. We have a perfectly adequate steel hood that will still mostly fit, but the hinges won't. Its also heavy as berkeley.

Why couldn't we tape it up real good, spread a bedsheet or two over it, pour a bunch of fiberglass resin on it, and make a race weight fiberglass hood for 30 bucks?

There has to be a reason that this wont work. I know the car stereo guys use fleece in their sub boxes, which have to be more rigid than a hood. But im not sure i can build a hood the same way.

We are also exploring pinning the stock hood and just gutting the structure from underneath.

why not just cut the hood inner out and add lightweight bracing NASCAR style

Looks like the Easy Button. Acid dip the hood outer for a Penske/ Donahue lightweight special. Nobody needs to know.

I think that technically if you did that you'd have a fibercotten hood coated in resin that might be a little bit flammable. Also, the hood you make will be bigger than the hood you're using as a mold. I think you'd want to use the existing hood to make a plug. Then you can take the plug and lay fiberglass weave and resin. While I've made and repaired things with fiberglass mat and weave, I've never tried to exactly duplicate something, though, so I might be missing something.

In reply to fasted58:

That's plan b.

Wae: exactly what I didn't think of. So, on to plan b.

With composites, you need to remember that the resin just holds the material in place. The material (fiberglass strands, carbon fiber strands, whatever) give it the strength. So, sheets? I don't think that's gonna work. Now, if you can get some fiberglass mat, that would work. Making a mold off the existing form gives you something that is bigger, but you can cut it down and make it fit.

Plan B is going to be easier.

you'll need hood pins, so add to that $30 figure

Hood pins are just bolts.

Keith Tanner wrote: Hood pins are just bolts.

So, what size and grade of bolt? Im thinking 1/2 grade 5 with holes drilled in for cotter keys. Should be able to get it all for about a dollar at tractor supply.

Keith Tanner wrote: Hood pins are just bolts.

Bolts are free if found in road side appliances.

Any good diy hood hinge information out there?

More bolts.

My hood pins are galvanized 1/2" carriage bolts, head cut off and hole drilled for linchpin

I have made fiberglass reproductions before. The only thing i missed was release agent, but i used cooking spray. It worked pretty well to make a mold of a camaro inner fender. I'll probably be making fenders for the $2018 car by using foam and bondo on the originals to make my shape, pulling a mold, and laying the new fenders.

Dusterbd13 wrote: Any good diy hood hinge information out there?

Lift off?

Stands like these would be worth concourse points if I was a judge. It should be noted that I'm not a judge.

Wasn't the Trabant body made out of some sort of cotton reinforced plastic? You'd need more than a couple bedsheets though, and fiberglass is cheap.

Do you actually need structure? Strip the inner structure, locate your hood pins, then cut out the bulk of any flat spaces on the hood. Take your new Swiss cheese sheet metal and put a layer of vinyl on top and bottom and vacuum out the air bubbles.

That typed though, stripping away the structure and hitting the sheet metal with the harbor freight bead roller to add some stiffness would be great too.

fasted58 wrote: why not just cut the hood inner out and add lightweight bracing NASCAR style Looks like the Easy Button. Acid dip the hood outer for a Penske/ Donahue lightweight special. Nobody needs to know.

I've done a bunch of these and they're super easy. Cut the bracing out but where the hood skin itself is bent 90deg and the inner brace is attached on the edges leave as much of the hood as you can. I've mostly done GMs and it's about 3/4 of an inch. Take a hammer and dolly and work that edge until it's bent 180deg against the inside of the hood and tack weld it every few inches. This stiffens the hood to help keep it from creasing and cracking. If it's still too floppy a simple light structure like the one pictured is easy to make from 1/2" square tube. To make hinges I'd cut them from 1/8" X1" steel. Cut four pieces about 3" long and weld one to each side of the hood at the rear corners standing upright, and one to each fender at the along side the ones on the hood. Lay the hood on and drill a 5/16 hole through both hinge pieces on each side and run a bolt through the hole for your pivot. You may need a spacer between the two hinge halves depending on how large a gap there is. Then take a sawzall and grinder to the hinges to cut them down and round them off and drill a couple small speed holes in them. I can try and draw out pics but it will have to wait until I get home.

In reply to patgizz:

foil against the body piece that you're molding eliminates the need for a release agent. That's the trick I've always used. There's still a good chance that the 323 gets some substantial fender flares using this method, especially if I get a deal on some wide 4x100 wheels to stuff 225 or wider rubber on.

A good wax job and a quick spray with Poly Vinyl Alcohol (PVA) should give excellent release. I saw an article on a Sentra SER that they tried the gut the hood deal and ended up with a mess. The braces are glued to the skin in many, many places. It ended up looking like Fido's back side! And it only took a few pounds out. My experience is that steel in cars is 2-3 lbs per square foot. Al is 1 and fiberglass is about 1/2. If you can vacuum bag it, you can get glass ratios around 70%, great strength, low weight. I rebuilt my kayak paddle this way and it can take a hit!

My concern with with fasted58's plan is do you have good source for Cheerios and Hamburger Helper decals? Just something to think about while still in the planning phase.

I think plan B is the way to go tho. It's a challenge car so simple, cheap, and effective is the way to go.

Chadeux wrote:

Dusterbd13 wrote: Any good diy hood hinge information out there?

Lift off? Stands like these would be worth concourse points if I was a judge. It should be noted that I'm not a judge.

If I were a judge - and I will neither confirm nor deny that I may or may not have been invited - I would give it concours points if it were raced in that condition.

oldopelguy wrote: Strip the inner structure, locate your hood pins, then cut out the bulk of any flat spaces on the hood. Take your new Swiss cheese sheet metal and put a layer of vinyl on top and bottom and vacuum out the air bubbles.

I did this on a geo metro once, because metros need to weigh less.

For a chalenge car it'll hold up just fine. street car, probably not.

AClockworkGarage wrote:

oldopelguy wrote: Strip the inner structure, locate your hood pins, then cut out the bulk of any flat spaces on the hood. Take your new Swiss cheese sheet metal and put a layer of vinyl on top and bottom and vacuum out the air bubbles.

I did this on a geo metro once, because metros need to weigh less. For a chalenge car it'll hold up just fine. street car, probably not.

The AE92 GTS, which is actually a not-too-distant relative of the Metro (since some were rebranded AE9x Corolla sedans), has an incredibly heavy hood. It could probably stop small arms fire. I've been thinking of separating the skin (which seems to be the mad-heavy part, it's about 2mm thick vs. the paper-thin frame) from the frame and putting an aluminum skin on it. A decent replica hood could be made with just a few simple bends on a sheet metal brake, radiused bends optional. Attaching the sheet aluminum skin to the steel frame would be the tricky part, probably some kind of glue like JB Weld would be the best bet, but that doesn't really inspire confidence that it won't separate at high speed.

In reply to GameboyRMH:

I think the Geo Metro was always a badge engineered version of the Suzuki Cultus (Swift in US). I don't think they were ever based on the Corolla. Now the Geo Prizm was a Corolla for sure! So was the 80s Chevy Nova.

Ah you're right, Geo Prizm is what I was thinking.

In reply to GameboyRMH:

I wouldn't do it with JB Weld. There are adhesives for what you want to do. They work very well.