Is this idea realistic or something that won't work?

[aggressive male]

I've been going to up22.com which is a place that sells fiberglass body parts for all kinds of cars. I was thinking about fiberglass doors because mine are very rotted at the bottom. Problem is it says you can but wouldn't want to use them on a street car because it's for bolt in windows only and there is no way they will go up and down. My question is do you guys think it could work to try to build the whole outer skin of the door out of fiberglass and also the bottom third of the inner shell (which is rotted) and just keep the inner shell 2/3 up the same? I plan on overlapping and bolting the fiberglass to the original material. Will this work well in the real world? Or fall apart?

[6'9"Witha69]

On a street car the will see regular door opening, closing, bumpy roads, speed bumps, dips, etc. I would not do it. I don't think the strength will be there and it will rattle apart.

[nbecker]

Forth-gen doors are glass so it possible

[6'9"Witha69]

Forth-gen doors are glass so it possibleYeah, but they're bonded to an inner structure designed to have a gless outer shell. 1st gen doors are not designed that way and will see considerable strength loss especially replacing the bottom 1/3 of the remaining structure in fglass. It would be more work to do it right than just fixing the doors.

[Taylor1969]

have you looked into buying replacement goodmark doors? I have them on my '69

[aggressive male]

Yeah, but they're bonded to an inner structure designed to have a gless outer shell. 1st gen doors are not designed that way and will see considerable strength loss especially replacing the bottom 1/3 of the remaining structure in fglass. It would be more work to do it right than just fixing the doors.Do these doors ever have problems falling apart? Maybe I can try to make mine like it?

[aggressive male]

have you looked into buying replacement goodmark doors? I have them on my '69 I would do that if they made them for a cadillac but I don't think anything is close enough to use. Sometimes I think about taking apart an old door to use as a pattern to try to make stainless steel doors. I'm confident about building the inner and outer shell but have no idea how to fabricate the window frame.

[aggressive male]

Forth-gen doors are glass so it possibleGlad to hear it! anyone know where I can find pics of the naked inner shell of a fourth gen door? I might want to try to build mine that way. Does it help make the car a fiberglass death trap?

[mikedc]

The idea of a 'glass outer skin on an original steel inner doorframe seems viable, but not quite like you're talking.

I would at least use an inner door structure that's not rotted (and use the whole inner structure). You would also be wise to beef it up a little at the corners, etc, to combat the flex from the missing door skin. If you crack the 'glass one time it will be more work than beefing up the inner structure would have been in the first place.

If you do this, then running a 'glass outer skin might work fine and drop a litttle weight. The window assembly would probably work no differently than stock if everything's done right.


You might also wanna consider some sort of extra door brace (side-impact issue) if the door didn't originally have one. Lookit a 4th-gen camaro. Those things basically have a hunk of rollbar tubing mounted behind the factory 'glass outer skin.



The whole project would probably work fine. But if you do it well then I doubt it would be any cheaper than just getting a set of intact original doors. Probably more. The end result could end up lighter & safer than the factory doors, though.

[NOT A TA]

If you build anything like that out of fiberglass it should be "baked" before painting. I used fiberglass on one car to rebuild a rusted area and it looked fine for a few years till I took the car to a show in Florida and left the car in a hot sunny parking lot for a weekend. The small trapped air bubbles in the fiberglass expanded from the heat and lifted the paint. 10 years later I still see the defects in the paint every time I have the car out. Big job to repaint so I keep driving it and putting it off.

[aggressive male]

This is an idea I like to play with too. How do you think I should beef up the door? Do you think another strip of sheet metal spot welded to the edges would be enough? These doors already have the side impact braces so I guess that helps a lot.


The idea of a 'glass outer skin on an original steel inner doorframe seems viable, but not quite like you're talking.

I would at least use an inner door structure that's not rotted (and use the whole inner structure). You would also be wise to beef it up a little at the corners, etc, to combat the flex from the missing door skin. If you crack the 'glass one time it will be more work than beefing up the inner structure would have been in the first place.

If you do this, then running a 'glass outer skin might work fine and drop a litttle weight. The window assembly would probably work no differently than stock if everything's done right.


You might also wanna consider some sort of extra door brace (side-impact issue) if the door didn't originally have one. Lookit a 4th-gen camaro. Those things basically have a hunk of rollbar tubing mounted behind the factory 'glass outer skin.



The whole project would probably work fine. But if you do it well then I doubt it would be any cheaper than just getting a set of intact original doors. Probably more. The end result could end up lighter & safer than the factory doors, though.

[aggressive male]

If you build anything like that out of fiberglass it should be "baked" before painting. I used fiberglass on one car to rebuild a rusted area and it looked fine for a few years till I took the car to a show in Florida and left the car in a hot sunny parking lot for a weekend. The small trapped air bubbles in the fiberglass expanded from the heat and lifted the paint. 10 years later I still see the defects in the paint every time I have the car out. Big job to repaint so I keep driving it and putting it off. Thanks for telling me about that. Thats the thing I like about fiberglass though, you can just put things like that off and flaws like that really don't get worse. If you do the same with steel the rust gets worse the longer you don't take care of it.

[68Formula]

Yeah, but they're bonded to an inner structure designed to have a gless outer shell. 1st gen doors are not designed that way and will see considerable strength loss especially replacing the bottom 1/3 of the remaining structure in fglass. It would be more work to do it right than just fixing the doors.

And even further, the 4th gen doors are not fiberglass, they are SMC. The coefficient of thermal expansion is much closer to steel and therefore less tendency to buckle under heat or cracking under extreme cold when attached to metal. It also contains carbon fiber and is stronger than fiberglass.

[aggressive male]

And even further, the 4th gen doors are not fiberglass, they are SMC. The coefficient of thermal expansion is much closer to steel and therefore less tendency to buckle under heat or cracking under extreme cold when attached to metal. It also contains carbon fiber and is stronger than fiberglass.What's SMC?

[68Formula]

What's SMC?

From another website, but summarizes it well:

Sheet molding composite (SMC) has become one of the basic building blocks of the automotive industry because of its low density, high tensile strength, corrosion resistance, and accommodation of parts-consolidation techniques. Moreover, advances in surface finish quality and reduction in manufacturing cycle times mean that SMC can replace steel or aluminum in any class-A exterior body panel and be cost-competitive at volumes in excess of 150,000 units. The sheet molding composite system is made up of a glass fiber reinforcement base, which is combined with resins, filler, release agents, catalysts, and oxide thickeners. SMC can be found in applications ranging from hoods and doors to underhood components, and in such structural components as cross-vehicle beams and integrated front-end assemblies.

[aggressive male]

Interesting.