Rust Information

Discussion in 'corvette related misc.' started by chasracer, Feb 5, 2019.

  1. chasracer

    chasracer Member

    Considering a 1979 Corvette - is there a comprehensive thread anywhere on typical rust problems with these cars? I owned a '66 roadster a long time ago - loved the car but the oldest was getting near 16 and I figured the better thing to do was let it go. So found this one locally and giving it some consideration but I had heard that there was more metal used in the construction than the earlier years and metal tends to equal rust.
  2. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    The Birdcage likes to rust they say.
    Water entry.

    The C3 Frame sometimes rusts out.
    Best to put on a car lift & inspect.
  3. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    diagram of areas that rust on c3 corvettes

    every part you may need to restore a c3-c4 corvette, is either available or can be fabricated
    anyone serious about restoring any corvette really needs a few tools,
    and access too a decent MIG WELDER in the 180 AMP-250 amp range,
    should be very high on that list.
    this all looks very complicated but its really not,
    theres plenty of info and step bye step guide's,
    yes its certainly time intensive and youll need a garage or shop space too work,
    but its more time and effort than high tech or difficult.
    do your research, purchase a few tools and books ,
    and anyone seriously into car restoration will no have much trouble.
    and obviously having an experienced and skilled mentor will be useful.

    This was bought to my attention by Tracy. Originally from Corvette forum ....

    RULE #1
    Before you even think about buying a C3 Corvette, you must know two VERY important facts:

    1.No matter what condition of car you buy, no matter the amount of money you spend, your car WILL eventually need work.

    2. NEVER NEVER buy a Corvette with out looking at it in person. EVER! If you must (like if you live overseas) only buy a car that you have recived sufficient picture documentation of the problem areas listed below. If you dont have positive proof, stay away

    Do not expect just because you spent $50,000 on a vette that you will never have to put more money into it. Remember, the newest C3 Corvettes are still 26 years old. If you can accept the fact you will have to put additional money into our Corvette, continue reading.

    RULE #2
    Decide what kind of C3 Corvette you want before you buy your first one. If you don’t, you will always wish you had bought ‘that chrome bumper car’ or ‘that ’75 vert’ you always wanted. Decide which year Corvette speaks to you.
    Here are some general examples:
    Chrome bumper VS Rubber Bumper
    All Original VS Custom
    Big Block VS Small Block
    Coupe VS Convertible
    Automatic Transmission VS Manuel Transmission
    Flat Rear Glass VS Bubble Rear Glass

    RULE #3
    Before you buy your first C3 Corvette, you need to know your personal mechanical abilities. Are you a complete novice when it comes to turning wrenches? Do you have a mentor or teacher that can teach you skills if you can’t afford to have other people work on the car for you? It would be wise to purchase a C3 corvette that falls within your mechanical ability to restore. Many people buy a car, and then find out they are in over their head to complete their project.

    RULE #4
    Know your financial ability to pay for a car, and your financial ability to put money into the car on a monthly basis. How much can you spend on the car per month? Also are you able to put money into the car if something drastic goes wrong? It’s always a sad thing to see a project Corvette sit in the garage because the owner ran out of money to put into it. Of course some of these situations are unavoidable, but wouldn’t you want to avoid it if you could?

    RULE #5
    When you find a potential project Corvette, there are a few main condition related items that your car should have if it is to be considered for purchase. Your car should ALWAYS have a solid frame, birdcage, and suspension. First let’s talk about the birdcage.
    Here is a picture of the Birdcage removed from a C3.


    In simple terms it is the metal frame that surrounds the cockpit area of your C3. It is vital that you have a solid birdcage because it supports a lot of your car. An easy way to check the condition of the birdcage is to remove the kick panels near your feet.

    Here are some pictures of how the mounts SHOULD NOT look like:


    If you find a Corvette with body mounts looking like this, RUN. They are a pain and expensive to fix, and there is always cars out there with sound birdcages for sale.

    A second area of rust that you can find on the birdcage is around the windshield. These areas can be accessed by removing the chrome trim and weather stripping around the outside of the windshield.

    Here are some pictures of what your windshield frame SHOULD NOT look like:


    Another important area to check for rust is the metal frame that makes up the support for everything on your car. Find a car with a solid, rot free frame. This means less money and headache to restore the car. It can be very costly to repair or even replace a rusty frame.

    Here are some pictures of what your frame SHOULD NOT look like:



    A good technique to determine if the car you are looking at has a good solid frame is to take a large flat blade screw driver and hit the frame with the end of it with force. When you hit the frame, hear a metallic sound, and only put tiny nicks in the metal, than your frame is good. If you can gouge deep in the frame and/or poke holes into it with your screw driver, than the frame is not what you want. The same technique can be applied to later model cars that have metal floors in them.

    Since C3 Corvettes are so old, the suspension should amost always be overhauled as a safety measure unless you can verify it has been done recently. Get a reliable mechanic to check it out if you can. As a general rule to the suspension AVOID suspension that looks like this:

    RULE #6
    Before buying your first C3 Corvette, another important area to look closely at is the condition of the fiberglass body. It can avoid you headaches in the future if you can find a body that has not had the chance to be poorly repaired by bubba. Tricks to seeing if you have a fiberglass body in good condition is to move your fingers around the inside lip of each wheel well. They should be smooth with no cracks. You can also look at the condition of the inside of the wheel wells. Also, check for cracks where to body mounts to the frame in the wheel wells.

    Body mounts SHOULD NOT look like this:
    Also avoid cars that have large damaged areas on them. Yes, they could be easy to repair, but you never know what kind of botched past repairs lurk underneath the paint, especially if the car clearly shows it’s been neglected.

    RULE #7
    When searching for a car, try to avoid cars that have been left outside or in a field for a long time (especially if you live in the colder climates). Cars outside deteriorate very very quickly, plus 99% of C3s leak. Also avoid cars with windows that have been left open for extended periods of time. This will ruin any chances of usable interior parts, or and hope of a solid floor.


    RULE #8
    Familiarize yourself with the different options and small changes that occurred to C3 Corvettes over the years. It will increase your ability to determine what is stock or not, what has been replaced or not, and what has been “bubba’d” or not. A quick way to tell if bubba has visited your C3 is by looking at the engine compartment. Lots of vacuum plugs? Twist ties? Crusted on oil? I think its so simple to just pop the hood, and can pretty much gauge the "bubba"ness from what that compartment looks like.

    DO NOT buy a car if it looks like this:

    RULE #9
    Write down the VIN number and also the trim tag information to determine some of the options the car came with, such as interior color, exterior color, and engine information. It is also a good idea to bring a Black Book with you to check the correctness of the VIN, trin tag vs colors and engine data. Also, compare the numbers on the block to the VIN to determine if the engine came with the car or not. This might be a deal breaker to some, but might be what some others want. Also, try your hardert to bring someone who knows vettes, especially C3s, and can be your second set of eyes while you look at the car.

    RULE #10
    After looking at the car you are contemplating about purchasing, make a list of items you think will need replacement. Take a look at catalogs and corvette supplier’s websites at prices for these items. This can give you an idea of what certain repairs will cost you. Also, after you go and look at the car, post real detailed pictures of what you saw so we can tell you if you should buy it or run away.

    Attached Images[​IMG][​IMG][​IMG][​IMG][​IMG]
    Last edited: Feb 6, 2019
  4. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    don.t ignore links thats where the majority of info is contained

    don,t get mentally over whelmed, its all rather easily done, it just takes research and persistence.
    if the frame needs extensive repairs you should use the info as a huge leverage to gert the cars price reduced


    Last edited: Feb 6, 2019
  5. drcook

    drcook Member

    One area of the frame, whether it is a C2 or a C3 that you must inspect is the "kickups". Follow the rear control arm into the boxed area of the frame. They will rust here, possibly before rusting other places. That boxed area captures dirt and debris and if someone was uncaring enough to drive the car in salt, it will eat through the frame there, even if other areas look sound.

    Good replacement frames cost a couple thousand from the ones I have seen. Aftermarket frames, especially performance oriented ones, go in the $8000.00 range from what I have seen advertised. They are tubular, and probably better than the OEM ones, but still, unless the car is particularly valuable, or you really have a high end goal in mind, they are pricey.
    Last edited: Feb 11, 2019
  6. chasracer

    chasracer Member

    Thanks for the replies. I ended up passing on that one, car wasn't terrible but I suppose the simplicity of the earlier cars is what I was looking for and tearing into this one just wasn't something that I could get fired up about.
  7. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    The later C4 Corvettes have Zero rust issues.
    Any Engine fits into them.
    The handling is superior.
    The only default they do not have the sleek curves of a C3.

    C5-C7 with its torque tube layout can not get the power down clean for drag race use.
    Need Slick and 300 -500 horsepower more than a traditional Musclecars need to run the same 1/4 mile time.
    C4 Corvette does well Drag Racing.
  8. drcook

    drcook Member

    Actually C4's can have rust issues. One problematic area that people need to inspect before buying is underneath the battery. A defective/leaking battery will eat holes through the frame that it is directly over. I have seen at least one post concerning this, probably over on the forum dedicated to Corvettes.
  9. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    I use an Optima Red Top battery in my 87 Corvette.
    The frame is fully galvanized dipped.

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