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Ok, I know the very basics about fiberglass, but never worked with it. I am wanting to attempt to reshape my transmission tunnel on my '32 Downs body. The arch is just too high over the bellhousing and I am going for more foot comfort around the gas pedal, it is to deep and high for my tastes. Any suggestions on building the gaps after I cut and what is a good realease for a mold or backer that won't stick to the resin?? Thanks in advance/
 

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To fill gaps you can use posterboard , masking tape, cardboard, aluminum or steel sheet, urethane foam, wood, paper mache, masonite, modeling clay, concrete, plaster of paris, bondo...

The rules are, can it be shaped into the shape you want? Will it stand up to the resin and pressure of being laminated upon? Can you wax it?
3 yesses means use it :thumbup:

I usually use a hot melt glue gun to stick poster board to my part, then peel it away after I do my laminate.

For a release agent you can use floor wax, mold release wax, surfboard wax, parriffin wax, poly vinyl alchohol.

Other releases are PAM cooking spray, vaseline, wd40 :pain:
Those will work, but can stay in the surface even after sanding and mess with your paint adhesion.

Not a big deal on a tranny tunnel, but it can make painting and finishing other parts hard.


Hope this helps, mikey
 

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Mike, you are making this sound way too simple, if i understand you you right simply build a mold with poster board and release agent then hot glue to my firewall and floor and go it.
 

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Brian Martin,Freelance adviser
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All I can say is listen to Mikey! He is a master at fiberglass having worked for one of the premiere (and oldest) repro body companies in rodding for many years.

Brian
 

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Mike, you are making this sound way too simple, if i understand you you right simply build a mold with poster board and release agent then hot glue to my firewall and floor and go it.
That's about it :thumbup:

All you really need is something to support the glass while it cures. Strong enough to keep from caving in while you roll out your laminate. I don't know how big of a hole you are patching. The bigger the hole the stiffer the material you need. Remember though that if you make a wavy shape with your mold. you'll get a wavy part. Make your patch mold tight to your existing part and you'll get a better job.

How much of the tunnel are you going to change?


Dont forget to rough up the edge of the existing floor with a grinder and clean it real good with acetone before you try to lay up to it.

I always peel the paper off and do a layup on the other side to balance the laminate. You need to grind your first layup smooth and blend it into the existing part. Resin won't stick well to a gelcoat finish unless it has been ground with a minimum of 40 grit.
If you have never worked with glass you would do well to search the forum and knowledge base here for some background info. Type "fiberglass" in the search box.
There are so many things to know about fiberglass that one thread can't contain them all.

MARTINSR, OneMoreTime, 302/z28, kenseth17 all those guys have written some good fiberglass advice here on the board.

Later, mikey
 

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Boy mikey, I wouldn't even put me anywhere in the same league as you and the other guys. I just fix semi hoods and did a little messing around with making fiberglass parts and molds, very minor stuff. I do use paste floor wax for release on little molds I've done. Seems to work alright.
If it just needs some reshaping to suit your tastes, maybe you don't even need to bother with a mold and extra material making one and whole part. Or maybe I read it wrong and thats what you are thinking. Does it look like you could use a cutoff wheel and modify the existing tunnel by cutting some away and moving the pieces back together closer to get the right shape you are after. Just a thought. You could then grind a v shape for more suface area where your cuts and gaps are grind the tunnel and surrounding down to bare fiberglass, duck tape the pieces and gaps underneath and spread on some mixed resin with a paint brush, lay up some mat, followed by soaking well with resin and pushing a little into your gaps, and continue to lay up layers aways past your cuts and gaps into the existing tunnel till you have good thickness layed up. Avoid being too resin rich, and work out air bubbles with the paint brush or a roller. I don't even own a roller yet myself. Bubbles or too much hardener or resin rich, or unsoaked mat will be voids and weaken. Then remove duct tape grind, and do the same thing on the bottom, laying up. Could be real fun and messy if overhead. Then just grind down your fiberglass and do some bodyfiller work if appearance is a concern. If the duct tape isn't strong enough to hold things well together, well then add more support somehow, like screwing some wood or adding some cardbord under the duct tape. Even tape the extra support with more duct tape, lol. You might not even need mold release If you use duct tape. I think your gonna want some kind of support to hold body in position if you cut apart the tunnel, and then you can probably tear off the duct tape while the resin is still a bit tacky. If it doesn't all come off, you can grind it off when you lay up more underneath. Once you have the top fiberglassed up, It should hold things in position, you are just adding more strength underneath and sandwitching your cuts and gap areas. Make sure this is fiberglass not smc. polyester Fiberglass resin will not work with smc, but resin that says for smc will work with both fiberglass and smc. Fiberglass fibers will be long and hairy when it breaks I guess you could say. Smc is compressed and tighter fibers. Think I got that right. Okay I am tired of saying duct tape now, and mikey please correct all my mistakes.
 

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i have used masking tape, duct tape to protect areas i didn't want the glass to stick to. i have also used cardboard to rough out a shape, then wet it with resin and glass matt then use a heat gun to force it to set faster. i have also used spray foam to make a center consel, shaped to what i wanted, then glassed it. once the glass cured, just carved out the foam from the inside.
 

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Brian Martin,Freelance adviser
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Mikey, all I have learned is from "gluing" motor homes back together. :) On the subject of "making" parts, it is pretty limited to using duct tape to build a shape for a whole corner of one of those fiberglass motorhome bodies (I used to call them hot tubs on wheels, when comparing them to the wood and sheetmetal variety :) ).

The thing was hit in the back and the whole corner was gone, a hole about two feet high by a foot across. I used about two rolls of duct tape and kept putting layer after layer mashing them tighter together and shaping them with my hands until I had the shape pretty close to matching the other side. I applied mat and resin to the inside and let it cure. I then peeled off the tape and what stuck to the resin I simply ground off with an 8 inch orbital sander shaping the thing for an Everglass application.

Mikey, don't be modest, you could put what I have done with fiberglass in your eye and you wouldn't feel it.

Brian
 

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re: looking for fiberglass advice

build your mold from whatever you have available (I use cardboard beer boxes) and duct tape. Keep cutting and taping until you have a shape you like. Cover the mold with "Saran Wrap" (clear plastic food wrap). Apply your fiberglass mat and resin until the desired thickness is achieved and then place another layer of saran wrap over the top of the wet fiberglass. Use a squeege to smooth out the air bubbles. When cured, simply remove the saran wrap from the "new fiberglass" (it peels right off) and remove the cardboard mold. Your new patch piece is ready to sand and paint. The plastic wrap can, with a little practice, produce a finished piece very smooth and professional looking. I just completed a fender flare for my motorhome using the one from the other side as a mold, covering it with saran wrap. When completed, the new flare was better looking (and stronger) than the original.
 

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Brian- I'm the last guy that you should tell to not be modest. My head is too big already. :p
Kenseth17, :thumbup: I saw no mistakes. (but it is duct tape, not "duck tape". here's yer brownie :D )

37 plymouth coupe :thumbup:
That seems like a good way for someone who has had minimal experience with fiberglass to get a good result.

Getting the air out and making a smooth part is hard when the resin is sticking to your tools and hands, and an inexperienced person will actually pull material away from the repair, or leave a bunch of air in.

The saran wrap makes things alot easier. Kind of like a economy vacuum bag.

This just illustrates how many good ways there are to do fiberglass and get good results.

Later, mikey
 

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Toeboards, why don't the new bodies have them?

This floor/transmission bump problem is common to many fiberglass bodies. The manufacturers are faced with making up a "universal" fit floor/firewall modification and the customer ends up with enough room between the transmission bellhousing and body floor to haul 7 illegals and their family dog under there.

One solution to the awkward throttle position which is easy to fab up, and is missing on repop bodies, but is stock from the factory, is toeboards. Toeboards, the slanted part of the floor which rises to the firewall on all stock cars but virtually no 'glass bodies, make a comfortable place to rest your feet. The angle allows a more natural non-tiring foot position and makes along trip much more comfortable. It is fairly easy to make a set using cardboard or posterboard as a pattern, then making a mock set from some thin Luan or other plywood. Test fit for comfort and control access , then make up some 5/8" plywood or even steel or aluminum ones for the real deal.
In a retrofit in an already built car you may find it necessary to modify your accelerator position or adjustment but hey you needed that anyway, didn't you?
 

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Carefull if you use a heat gun though. It is very easy to start cooking the fiberglass and make the resin brittle. If you have the time, just let it sit in cure naturally if the room is warm enough. Of just carefully warm it keeping the heat gun moving and back a little ways. Once it gets a little heat blown on it, it should start kicking. Could also use an infrared heat lamp if you got one. Again not too close or too long. Also there is a difference in resins it seems.I can do a much better job with the smc and fiberglass resin (mixes with cream hardener (white- resin turns green when mixed well) instead of a liquid hardener) then I can with polyester resin(even counting the drops per ounce. It seems too me the smc and fiberglass stuff we use gives more time to work, but still kicks and able to sand or grind in a reasonable time, while the polyester rushing to get it on and everything layed up neat If you are going to do alot at one time. But the smc resin is about 60/gal vs 30/gal. Think smc we use is evercoat if I remember right. Yep, here is what we use.
http://www.evercoat.com/productDetail.aspx?pID=16
Notice it says polyester resin also. Maybe someone could explain the difference between a polyester fiberglass resin and one that can be used with smc, I have no clue what is different between the two, if they both say polyester.
 

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Here is what I think the difference is....
Polyester resin is the base for a whole bunch of laminating resins, coatings and fillers.
I saw in the msds sheet for that SMC resin that it uses an additional ingredient, methyl methacrylate, which typically is not in bondo or polyester laminating resin.

It's typical uses are in making acrylic panels. I'll bet that its presence in that resin made for smc is to promote adhesion, as SMC is less apt to have secondary laminations stick to it.

So that's probably why the SMC resin will work better on both polyester and SMC.

( I used to use this stuff called AME4000B, which was an "acrylic modified epoxy" That stuff would stick to anything. I bet it had that meth stuff in it too.)


I think also the SMC resin is double promoted, as it uses a BPO catalyst instead of MEKP.

What all that actually means to you and me is questionable.



BTW, It's very doubtful that the Downs Mfg body has any SMC parts on it. Downs makes all their stuff in open molds, the old fashioned way, with room temperature cure resins. Unless maybe they have gotten more sophisticated in the last few years..

I wonder what someone who is a real chemist woud say about this stuff.

Later, mikey
 

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kenseth17 said:
Carefull if you use a heat gun though. It is very easy to start cooking the fiberglass and make the resin brittle. If you have the time, just let it sit in cure naturally if the room is warm enough. Of just carefully warm it keeping the heat gun moving and back a little ways. Once it gets a little heat blown on it, it should start kicking.
exactly forgot that. just used the heat gun to force it to set a little faster and help my compound curve. worked a small area and moved across from there. it set pretty fast. i also use it to "kick" gelcoat when my friends ask me to fix their ricer body kits the broke on speedbumps.
 

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mikey said above "I wonder what someone who is a real chemist would say about this stuff"

Well, I'm a chemist, but I can answer only some, but not all of your questions/comments. Mikey has probably heard all this stuff before, but perhaps some of the following might be helpful to others who read this board.

The methyl methacrylate serves essentially the same function as styrene does. Both methyl methacrylate and styrene contain unsaturated sites which will react readily (after catalyzation) with the maleic or fumaric unsaturated sites that are in the polyester resin backbone. The maleic or fumaric sites will react with styrene monomer (or with methy methacrylate), but not readily with other maleic or fumaric sites. Of course, another thing these reactive monomers do is to provide a usable viscosity at room temperature. You can consider both MMA and styrene as "reactive solvents" and in another sense as a sort of curing agent for the polyester unsaturation. One thing MMA does better than styrene is improve weatherability. I'm not a formulator of sheet molding compounds, but I suspect that there are other factors besides the use of some methyl methacrylate that helps provide adhesion to SMC. To kenseth's comment, I really am not familiar enough with formulating SMC to be able to say exactly what all of the differences are between a polyester for SMC and one for cold laminating. It seems reasonable to assume, though, that one major difference is in the promotor package (things like cobalt and amine levels) to get the desired reactivity for a particular type of peroxide, at the desired cure temperature. Different peroxides decompose at different rates, and the promotor/inhibitor/peroxide combination will typically be taylored according to the gel time, cure speed, and cure temperature that is desired. Which is one reason that its a bad idea to use a different type of peroxide than is recommended by the manufacturer (unless you feel really lucky that is, or are willing to do controlled experiments).

You're absolutely right that one use of MMA is in clear plastics such as plexiglass, which is basically pure poly(methyl methacrylate). Another use is as a monomer for making acrylic resins, such as are used for acrylic-urethane topcoats, although for that use the MMA will certainly be blended with other co-monomers.

By the way Mikey, I want to add my two cents to Martin's earlier comment, and say that I also have an enormous amount of respect for your experience making laminates. I did my first large laminating project a few years ago (a '33 mold, followed by a body made from it), and felt like I'd worked my poor tail off before it was done! Before I ever do that again, I'm going to find a helper, or not do it!
 

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Thank you, Powderbill, I am glad to hear that my educated guess about the Methyl Acrylate was right. And thank you for the compliment. I need to point out that I was fortunate to learn many of the things I know from a man who has been involved with fiberglass since 1948 and made it his business in 1967.

It helps to have helpers on big jobs.

The biggest mold I ever made was for the hull of a 65 foot catamaran. I shot the chopper gun and had 12 helpers. If my memory serves me correctly, the primary laminate, before the core and reinforcement took 9 barrels of resin,(4500#) and about 2000# of gun roving, as well as 1000# of 3 oz chopped strand mat. We used up all that material in 2 days.
It was for a yatcht company in the carribean islands that hired me to show them how to build a mold. Prior to that they buily all their boats with stations and lathing and did the finish work by hand. :pain: Ever see a 12' long sanding block?
That was a job. :thumbup:
I have some pics on paper, someday I'll scan them in.

Later, mikey
 

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Powderbill-After I wrote that last post it occured to me that I never thanked you for that insight into the chemistry of resin. You are right in that I've read about those things you wrote about, but I have trouble keeping it all together.
The chemical reactions are way too complex for a guy like me to understand, I'm glad there are people like you who can understand it.

Just the fact that a resin starts out hard, gets cooked into something thin, has inhibitors added to keep it thin for more than a few hours,(hardness in a few hours is what would normally occur), then has promoters added to make it get hard faster when you do add catalyst...
It's very confusing...like living with a woman with PMS. :boxing: :eek: :D :drunk: :smash:
At the fabrication shop level, we are fortunate that we don't need to know alot of the chemistry.

I know some specialty resins need to be promoted at the time of use. It is packaged like that to give the ultimate strength. Normal resin gets hard just waiting to be used.

They use cobalt and DMA as promotors. Don't add one into the other or add the MEKP too soon or else you'll be getting out the fire extinguisher.

I believe that SMC uses a filled resin and is made in closed heated molds using an injection process. I believe that the release agent is in the resin, this is why you need to use a different resin to stick to smc. I have to admit that I'm just guessing here.

Later, mikey
 

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Discussion Starter #18
Thanks!!

Thanks, everyone for the great advice, it turned out ok, of coarse more to do but for first time I am very pleased. Mikey I will attempt to post some pics and you can grade my work, ignore the cardboard, I will be doing a coat on the outside when I lift the body off. Much more foot room for throttle, and as you can see my Downs body has the angled floor. Thanks again!!
 
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