Fiberglass bodies and wood...?

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T2T

Still running with scissors!
Joined
May 18, 2007
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What kind of wood should I use to reinforce the body on my RPU.........? I need to know from someone that has actually done this or someone that knows. 5/8" plywood seems pretty good to me , but what do I know?

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You can't use steel. It has a different expansion/contraction rate than fiberglass. Wood is the preferred material to use. I bought select pine at the local Home Depot, and cut it to fit. Give me a little while (I just got in and haven't eaten yet) and I'll post some pictures showing how I did mine.

Don
 
Ok Tom, my dinner is cooking, so I'll get started. This is going to be a long thread, because I have to break it up into lots of posts. My computer is screwing up, and if my post is too long, it freezes up, and I have to shut it off and start over. Plus, it is impossible to explan fiberglassing in a short post. So here goes:

First of all, your choice of 5/8 plywood is good. I use exterior grade sheating plywood. Marine grade is not needed and is hard to find and expensive. You will be coating it with fiberglass and resin, so it will never rot, plus it already has waterproof glue bonding it. You will want to cut the plywood slightly smaller than the area it needs to cover, so the plywood is not touching the body. Leave a gap all the way around of about 1/4 -3/8 inch. Otherwise you will get shadowing through the glass. (don't ask, too long to explain)

The floor is the first thing to install. Set the body on the frame as you want it to end up, and place your cut out floor inside. Shim it up to allow room for body mounting rubber.

Here is mine after that process.

Don
 

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Next thing you will want to cut out is the piece of plywood that will be the inside of your firewall. Here is mine.

Notice the gap I left around the wood in the last picture, for the same shadowing reasons.
 

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Good time to talk about materials you will use. There are two kinds of resin, polyester and epoxy. Epoxy is better, holds better, and is much more expensive. You do not need to use epoxy, even most boats are made from polyester. It is what I always use. Buy your resin and cloth from a marine discount store. Not one of the ones like West Marine or Boaters World, but a real hole in the wall marine supply house, or a fiberglass house. Otherwise you will pay way too much.Buy your resin in gallons, as shown below.

I used three gallons to do my '23 T bucket.
 

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There are two kinds of fiberglass material (actually lots more than two, but two MAIN types) One is called mat, and is the stuff that has random strands running in all directions, and the other is cloth, and is the woven one that has a crisscross pattern to it.

I use mat only because it conforms better, and bites into whatever you are bonding it to better. Here is mat. I bought 10 yards and will need more to finish. It cuts with scissors.
 

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Some tools you will need are:

Scissors you don't care about (they will become coated with resin after a while.

Throwaway paint brushes

Rollers as shown below to push the glass into corners and roll out bubbles

Mixing buckets.
 

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Buy yourself a gallon of acetone and at least a gallon of wash thinner (cheap laquer thinner) If you buy one gallon at Home Depot it's $ 14, if you buy 5 gallons at the automotive paint store, you get 5 gallons for $ 32. Much better deal.

I also buy my plastic buckets at the auto paint store, much cheaper. Buy lots of them, you will be using them a lot. Get stir sticks too. I also buy latex gloves by the box of 100, you will use these constantly during the fiberglassing process.

Now that you have your floor and firewall cut out, you have to wipe down the entire interior of the body with acetone to remove any mold release wax. Fiberglass does not cure unless wax is in it, and this wax rises to the surface when it cures. You need to remove it with rags and acetone. Then grind every inch of the interior with something like 60 grit to give tooth to the surface, and then wipe it again with acetone.

Here is mine after all that.
 

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You are now ready to begin fiberglassing. First, cut up lots of mat into various lengths and widths. Make some 2 x 4 inches, some 3 x 6 , and some longer and wider. When you are joining the wood to the fiberglass, the process is called tabbing. You are making up "tabs" of mat and wetting them out so they adhere to the fiberglass. You want to put a 2 inch wide piece down first, then when you go back over it, put a 3 inch piece over it. The idea is to not have the tabs all end up at the same spot, or you will get stress points. Progressively go wider and wider with your edges.

Here is a sample of what you will cut up.

Picture two shows the first layer of mat pushed into an L shaped piece with part of it on the wood, and part on the fiberglass sides. You first paint a wet layer of resin down, then push the mat into it with the brush, then dab on more resin until the white mat is translucent in color. You can't brush it, you have to dab it on, as the mat will pull away if you dont.
 

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Ok, my dinner is cooked, so I am going to go eat (it's almost 2 am and I just got in from the shop a while ago)

But to give you a little preview of what you will be doing, here are some pictures further along.

I'll continue with this for you tomorrow.

Don


PS: Oh yeah, buy yourself LOTS of clamps, you will be needing them. :D :D
 

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It is sort of like trying to explain how to build a house, you can't do it in one sentence. :D Sorry to spread it out this way, but between this stupid computer that freezes up with no warning, and the need to post lots of pictures as I go, I could think of no other way.

Ok, I have a little time before I have to go, so let me say a few more words.

One thing you will become very familiar with in fiberglassing is the ITCH. When you grind fiberglass, the little particles of dust imbed in your pores and you will feel like you have little slivers sticking out of you for about 24 hours. One day I came home from work and decided to do some work on my '27. It was a hot day, and as usual, I was wearing only shorts and tennis shoes. I ground away with a body grinder, and was sweating, so all this dust was sticking to my body. That night I slept with no covers or sheets on me, with my arms outstretched. :eek: :eek: I couldn't stand for anything to touch me until it wore off.

There are some things you can do. Those paper suits they sell for about $ 10 are worth their weight in gold. Blow off with compressed air occasionally during the work. Baby oil used liberally as you shower will coat the dust and float it away from your pores, shower in cool water, and some people say to rub panty hose up and down your body and it grabs the fibers. (There are about 100 jokes here, but I won't touch them :D )

The best solution though is to do it outside and wear the paper suit, and blow off. I did that on my newest T project, and never got any itch.

Don
 
Ok, I got through that without computer freeze. :D

Last thing we discussed was tabbing in the floor. I might add that you will want to mix up only as much resin as you can use in about 15 minutes. It will start to kick (harden) on you after that, and you will waste whatever is in the pot. You can continue to use the same brush, usually, for several pots.

Precut all of the mat you think you will need to use before you start. It is very hard to cut mat when your fingers are all coated with resin, and they will be coated. Wear throwaway latex gloves.

You can keep laying up layers of mat, one atop each other, for as many layers as you wish, but once you stop, and it cures, you have to grind it to get the wax that has risen to the top off. But as long as you are doing it at the same time, you can just keep going and going. Usually about 3 layers are about right for any corner tabs you do.

Mix the resin according to the can, and stir well. Paint on a heavy coat to wet out the underside of the mat you are about to lay down, then keep dabbing on more until it is translucent. You can keep putting successive layers onto the wet mat, and repeating that process.

For the piece that you want to install on the firewall, cut several pieces of mat the shape of the firewall (slightly bigger so it overlaps the side of the body a little) and paint a layer of resin all over the firewall. Then lay the first piece of mat down and dab enough resin all over it to wet it out, then repeat until you have 3 layers wetted out. What you are doing is creating a sticky base for the plywood to be placed onto.

Put the plywood down into this wet mat, center it, and put heavy weights on top of it to squish it down into the mat, and hold it until it cures. Let it set overnight, if possible, to get a good cure.

Here are some pictures of that.


Picture 1 is the dust I am talking about. This is after grinding the firewall interior.

Picture 2 is the firewall with a coat of resin painted on it

Picture 3 is the first layer of mat laid into the wet resin, but I have not painted a coat of resin on top of the mat yet....it is still dry

Picture 4 shows the heavy weights sitting on top of the finished plywood intall, till it dries.
 

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Once the fiberglass has cured, the plywood is now bonded tightly to the body. But you will want to put at least one layer of mat on the inside of the plywood to further bond it to the body, and to make it water proof.

Here are some shots of mine after that process.

The first picture is simply the firewall after the outside layer of mat is installed

The second picture shows black on there. What I did was paint truck bed liner all over the areas where I would not be glassing. These bodies are thin, and light will show through. My plan is to paint the entire inside with bed liner so that it appears thicker to light. I have seen fiberglass bodies where you could almost see through them even after they were painted, that is why I am doing this step.
 

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Now, on a traditional T body, you would have to do no more to the firewall, but on mine, I decided to run the steering through the firewall, as opposed to through the floor, so I needed a lot more strenght there. Fiberglass has no strenth by itself, you have to put a subframe into it when you intend on putting stress on it. That is why you do the wooding.

For my firewall, I wanted a very strong subframe to support my steering column and my windshield, so I built a steel "roll bar" affair to hold these items. Now, the reason steel will work here is because it is not glassed to the body, it is bolted through it. Steel will not bond well to fiberglass, and even if it did, it would start seperating after a while. That is why my cowl roll bar is bolted in.

Here is how I did that.

Picture 1 is the roll bar I bent up

Picture 2 is the foot I made to bolt it to the frame

Picture 3 is it in place

Picture 4 is after it was finished and painted (had to paint it before I installed it because it will never be able to come out of the body again once the floor is glass in place, it is now part of the body)

Picture 5 shows how all the stress is put onto the roll bar, not the fiberglass body.
 

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Ok, now that you have the floor and firewall glassed in, the next step is to do the "stringers" or ribs that will go on the sides and back of the body. If you are putting in a door, your framework on the passenger side will be different. I see you have two opening doors, so you will have to build a jam on the inside of the door and also the body. You will want to install some kind of steel plates for the hinges to screw into so they never come loose.

Most fiberglass bodies are wooded the same way on the sides. A top cap of wood is run around the upper edge of the body, and vertical stringers are run from that point down. As I mentioned, I use select pine. Do not use a hard wood like oak. It is too closed grained to let resin soak in, so you do not get a good bond. Pine is cheap and perfect, and select pine is nicer to work with, and not much more money.

I begin by building the entire top cap that lays under the lip, and do it in sections so that it lays nicely against the body contours. These bodies have twists and turns in all directions, so you have to shape the wood to lay flat. I used a bandsaw and belt sander to shape the wood, but a jigsaw and body grinder will work too.

You want the interior side of the wood to present a flat surface so that your upholstery board will lay flat against it, so you shape the backside to accomplish that. As you go, clamp eac piece into place until you have the whole interior cut, then do your glassing all at once.

Here are more of the pictures I posted previously. Like I said, you will need lots of clamps (Harbor Freight).

Picture one shows the contour of one piece after I shaped it. You need to do this to get it to lay tight against the body.

You will notice in the last picture I numbered each piece of wood, so that I would know where it went when I was glassing them in. I drew a chart and hung it up so I had a map to follow.

Time for me to run, but I'll post more later for you.

Don
 

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Once you have the stringers all cut so that they fit well against the body you can start glassing them in place. The way you do that is to cut strips of mat just slightly wider than the wood, and put a couple or three layers of wet mat under each one to act like a cushion. Then you clamp or wedge each stringer into the wet mat, squishing the resin down, until it cures.

You have to do whatever you can to wedge it into place. Here is a picture of how I had to use pieces of wood and clamps to force each one up against the body until it cured.


Don
 

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