C2 and C3 frame rust under car covers

[Walter F.]

I have made some posst asking about frame and birdcage rust on C2 and C3 Corvettes. Where I live on Long Island, New York C3 Corvettes are a very common sight, all years. I would say most of the cars I know of (one across the street). sit outside all year long under car covers. We have a lot of damp and cold winters being and Island. Are these cars safe from frame rust left out all year long under car covers in a driveway ? I have been told dampness car rust cars, especially cars built in the 1960s and 1970s.

[Michael W.]

Re: C2 and C3 frame rust under car covers

Are these cars safe from frame rust left out all year long under car covers in a driveway ?

Sitting outside trapped under a cover is only marginally better than driving them in salt and snow.

[Ed S.]

Re: C2 and C3 frame rust under car covers

Walter,

The extent of frame rust will depend largely on where the car spent its first 40 years or so and how well it was protected from the elements since it was born. A lot of the serious rust you see on C2 & C3 frames comes from all sorts of road grim (mud, sand, salt, leaves etc.) being thrown up into nooks and crannies where it gets lodged and then retains moisture,over and over - and probably never dries out. Today, if a car is relatively free of those types of mud cakes the worst you will get on a frame is surface rust - of course years and years of surface rust could become serious cancer. All that said, humidity like you get in LI is probably not enough to do anything but surface rust to a frame that is solid. Damage to birdcages comes largely from leaking seals around windows doors - it comes from the top down - so again, if these cars you are seeing around LI have been protected from the elements and water has not penetrated beyond the outside skin (the body) via bad gaskets and seals then I suspect that car covers would prevent more water from seeping down into vulnerable areas. And, if the seals have not been properly replaced several times over the last 40 years or so they probably don't seal very much.

[Gene M.]

Re: C2 and C3 frame rust under car covers

Steel mixes with any and/or all like salt, salt air, excessive moisture, chlorine, acid, and forms rust. The key is to surface protect it as best one can with an epoxy and/or urethane paint. Plated surface is better than nothing but the sacrificial properties is lost in time. These cars were never intended to still be around 50 years later. If only everything steel was 316 stainless steel our beloved Corvettes could still be more original than they are now.............

[Duke W.]

Re: C2 and C3 frame rust under car covers

I have been told dampness car rust cars, especially cars built in the 1960s and 1970s.

Common rust on ferrous metals is an electrolytic corrosion process that requires an electrolyte, which is commonly liquid water and any salt. Take away the liquid water and there is virtually no corrosion.

So, yes, even leaving a car outside exposed to overnight condensation will, in the long run, accelerate corrosion, compared to being kept in a non-condensing humidity environment.

The biggest advantage to a car cover is protecting the interior and exterior from UV radiation, which is greatest in the summer.

It may be best NOT to use a cover if the car is outside during winter, unless it's in the sun most of the day, so absorbed moisture is baked out., but Ed brought up a good point about making sure that all weather seals are in good condition and don't leak to protect the birdcage.

Duke

[Mark E.]

Re: C2 and C3 frame rust under car covers

Who knew there are a lot of C2s/C3s sitting outside under a car cover on Long Island?

Most birdcage rust is caused by water leaks around the windshield, T-Top frame, and cowl. Using a weather proof cover should virtually eliminate that.

Frame rust is caused by driving on road salt; some corrosion may be caused by moisture retained by trapped debris and dirt. Since this is a function of driving and cleaning habits; a car cover won't help prevent this.

Exposing the car to moisture trapped under a cover for long periods of time can cause corrosion as well, but differently. The effect looks like what happens when a car lives in a high humidify environment: The finish of all exposed metal components is tarnished/weathered or has surface corrosion.

Good quality car covers are designed to be almost weatherproof (i.e. block precipitation) while allowing moisture inside to escape. So using a good car cover will prevent birdcage corrosion due to leaks, and not contribute to corrosion due to trapped moisture.

[Don H.]

Re: C2 and C3 frame rust under car covers

In 1985 I bought a '64 Coupe in Florida. When I did a title search through the DMV (back when you could for a modest fee) I discovered the car had been in Florida all it's life - the first owner was a lady (it had auto & AC). I was excited that the frame was perfect as I live in Iowa with lots of road salt. BUT, the birdcage, radiator support, etc had significant rust from salt air! I was told a previous owner lived on the beach but "keep it in a garage with a cover." I never even thought about the salt air. Don H.

[Mark E.]

Re: C2 and C3 frame rust under car covers

...the birdcage, radiator support, etc had significant rust from salt air! I was told a previous owner lived on the beach but "keep it in a garage with a cover." I never even thought about the salt air. Don H.

Donald,

Birdcage rust I've seen was caused by water leaks. Most damage was at the bottom of the windshield frame and behind the kick panels where water can collect.

So what does birdcage rust caused by salt air look like? I'm wondering if damage is more even across surfaces, but with less localized damage (compared to water leak damage).

[John R.]

Re: C2 and C3 frame rust under car covers

Walter,

This is a topic of great interest to me and one I've thought about and researched on and off for years. I live on Long Island, have 5 vehicles that I really love and indoor parking for just one. You can probably guess that the Corvette gets the indoor spot. I still own my 86 Mazda Pickup and 91 Toyota MR2, both bought new. The truck is off the road due to a rotted frame.

The interiors of my '04 BMW and my '86 pickup both suffered greatly due to the sun. The MR2 was always under a car cover and the interior looks brand new. Aside from driving on our salted roads, the sun seems to have caused the most damage to my vehicles. If stored outside, a car cover is a must for me.

For the underside of the cars, and especially the frames I have decided that the best course of action is to use some sort of film. This won't fly if the underside of your car is displayed with mirrors at shows, but if driving is what you like it may be worth a look. Most of the film type undercoating, like Fluidfilm don't specify that they are rubber safe and since I want to spray everything, including brake lines, I won't use that. After a bunch of research I found LPS3. It is safe on rubber and plastics, but it will protect unpainted metal, even if it's already rusty. For the areas inside the frame I may use either LPS3 or good old fashioned Waxoyl from the U.K.

For a driver, my thought is that any hard coating will eventually be penetrated by a rock or some other road debris and fail. In the case of my Corvette, there is rust inside the frame and I want to stop it from spreading. An undercoating gun with flexible extensions is fairly inexpensive and protecting the frame from the inside will put my mind at ease. Even if I weren't going to spray the outside, I'd do the invisible inside of the frame. Also, you can always use a detergent to wash it all off, so it's a reversible process.

Here is a link to a study done on such coatings. It's very practical and I encourage you to read through it:

http://www.tc.faa.gov/logistics/grants/pdf/1996/96-g-001.pdf

I drive another one of my trucks on the beach and this is how I plan on protecting it.

Hope this helps.

[Don H.]

Re: C2 and C3 frame rust under car covers

Donald,

Birdcage rust I've seen was caused by water leaks. Most damage was at the bottom of the windshield frame and behind the kick panels where water can collect.

So what does birdcage rust caused by salt air look like? I'm wondering if damage is more even across surfaces, but with less localized damage (compared to water leak damage).

I probably should not have used the term "birdcage." The front door "gutters" were bad. One side could be repaired, the other side had to be replaced. I have a theory on the common coupe gutter rust issue that the sealant applied in the gutter by the factory would get moisture between it and the metal, then comes the rust. The car I had probably had this rust advanced by the salt air but it happens to coupes everywhere. Another area I believe corrosion was caused by the salt air was the aluminum fins on the AC condenser, they were very bad. Don H.

[Duke W.]

Re: C2 and C3 frame rust under car covers

In 1985 I bought a '64 Coupe in Florida. When I did a title search through the DMV (back when you could for a modest fee) I discovered the car had been in Florida all it's life - the first owner was a lady (it had auto & AC). I was excited that the frame was perfect as I live in Iowa with lots of road salt. BUT, the birdcage, radiator support, etc had significant rust from salt air! I was told a previous owner lived on the beach but "keep it in a garage with a cover." I never even thought about the salt air. Don H.

About 20 years ago I ran across a car in a parking lot that must have spent its entire life outside within a block of the beach. It was rusted from the top down... rust all around the windows and the cowl panel was perforated. I looked underneath and the chassis was relatively clean and completely rust free.

When there's a high enough surf that the waves break well before they reach the shore and a good breeze you can actually see a "salt mist" that moves onto the shore.

The car was a '76 Vega Hatchback! Fortunately my '76 Cosworth Vega has always been garaged and is completely rust free, and since I'm about a mile up from the beach over a hill, the salt mist doesn't make it to my place.

Duke

[Bruce M.]

Re: C2 and C3 frame rust under car covers

Sometimes a little rust is a good thing. It provides a slight protective coating on the steel underneath, not entirely unlike anodized aluminum. In fact you have probably seen examples of an even better type of rust protection that forms on corten steel, which creates an impervious barrier to further corrosion. Corten is rather expensive and used for light poles and guard rails where a brown, wood-like appearance is desired and is maintenance free. Of course our Corvette frames and parts are not corten, and the rust gradually builds up and flakes off, taking what used to be steel with it. Humidity induced rust is probably more of the protective type (like corten) and unlikely to cause structural problems... just my guess.