Rust Information

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.
 
The Birdcage likes to rust they say.
Water entry.

The C3 Frame sometimes rusts out.
Best to put on a car lift & inspect.
 
diagram of areas that rust on c3 corvettes
https://www.cartechbooks.com/how-to...y_diy&utm_medium=blog_post&utm_campaign=sa248

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 http://forums.corvetteforum.com ....




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.
Birdcage:
Here is a picture of the Birdcage removed from a C3.

nono10.jpg


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:

nono9.jpg



DSCN2359.jpg

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:
windshieldrot.jpg


DSCN2362.jpg



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:
DSCN2352.jpg


nono5.jpg


nono4.jpg


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:

nono7.jpg

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:
nono8.jpg

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.


possible001.jpg


possible003.jpg

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:
nono.jpg


nono2.jpg

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
47681710d1317949535-extreme-birdcage-rust-433.jpg
47681711d1317949535-extreme-birdcage-rust-dscn0305.jpg
47681712d1317949535-extreme-birdcage-rust-dscn0394.jpg
47681713d1317949535-extreme-birdcage-rust-dscn0395.jpg
47681714d1317949535-extreme-birdcage-rust-dscn0396.jpg
 
Last edited:

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.

http://www.superchevy.com/how-to/vemp-1102-corvette-frame-restoration/

http://www.corvetteusa.com/windshieldframes.html

http://garage.grumpysperformance.co...71-vette-how-to-change-body.14930/#post-84235

http://garage.grumpysperformance.com/index.php?threads/restore-or-walk-away.13112/#post-68367

http://www.vettefinders.com/1978_corvette_pace_car/resources.cfm

https://www.zip-corvette.com/68-82-c3/frame-chassis/corvette-frame-repair-components.html

http://www.bairscorvette.com/c3framerepair&components.html

https://www.paragoncorvette.com/c-23617-repair-sections.aspx

https://www.mamotorworks.com/corvette/category/c3-body-mounts-frame-underbody-sheetmetal

https://www.bestbuyautoequipment.co...MI2Ovn0rSn4AIVlo7ICh2ODATFEAQYASABEgIxs_D_BwE
Melissa-lift001.jpg

if the frame needs extensive repairs you should use the info as a huge leverage to gert the cars price reduced
Auto-Lift-Rotisserie_lg.jpg


https://www.corvettemods.com/search_results.html?p=2&sn=162589161&e=rsp&ajx=1&nsrt=NAM_A0&tag=CATSC3+Corvette+1968-1982;Exterior|SCTSRestoration+Components|XIDSC332

https://www.corvetteonline.com/buyer-guides/the-corvette-online-c3-buyers-guide/
Frame070.jpg

27348200ca5e91046ff32245be828b03

https://www.chicagocorvette.net/diagram_view.php?d=2223&rc=1848

C-BODY-07-mount-kits.gif

eastltd said:
Depending on the extent of the rust you may have to pull the body to repair it properly.

I know that's not what you want to hear, but...

Here are a couple of shots of the frame repair we did. Hope they help.

DSC02523.jpg


FirstCut.jpg


Fit-up1.jpg


Fit-up2.jpg


LeftRailbottom.jpg


Leftrailend.jpg

user_offline.gif


body10.jpg

2015-09-27_18-39-33.jpg

s-l500.jpg
 
Last edited:
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:
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.
 
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.
 
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.
 
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.
Possible.
I use an Optima Red Top battery in my 87 Corvette.
The frame is fully galvanized dipped.
 
Strange stuff.
No rust on my C4 frame anywhere.

A 1969 GTO RAIV 4-speed surfaced after 45 years in storage off the coast of Florida.
There is 3 foot rust hole clean through the hood.
Never seen rust so bad.
Sunshine state.
That salt air is bad on steel.
 
Check out the rusted frame on this one, and what had to be done to repair it. This one was caused by a leaking battery.

"Frame Repair
After getting her all stripped down we discovered that the battery tray was covering up a little bit of a mess. At some time in our car’s life the battery leaked and started to eat through the frame. We decided that the best thing would be to fix the bad spot in the frame."

https://www.corvetteforum.com/forum...873-c4-race-car-build-roadrace-endurance.html
 
Check out the rusted frame on this one, and what had to be done to repair it. This one was caused by a leaking battery.



https://www.corvetteforum.com/forum...873-c4-race-car-build-roadrace-endurance.html
I put an Optima Red Top battery in my 87 Corvette Convertible back in 2011.
I pulled the Lower drivers front plastic fender gill to install the Optima.
No rust on my frame.
Sulphuric Acid eats steel yes.
No leaking battery in my Vette.
Optima batteries are leakproof.
 
I keep telling people how great a bargain they are. Over on CF, I put together a post showing how easy it was to make a C4 Corvette outperform a lot (not all) but a lot of today's "muscle" cars because of the power to weight ratio and the fact that the basis in cost is so much less.

Dodge Decimated Corvette on the Streets and Dragstrip.

Yes, but it is easy to outdo them, but "perceptions" are what people go on. Take the top of the line Challenger, it has
797 HP and 707 LB-FT of Torque. From what I can see on the web, its weight is 4443 lbs. That is 5.57 lbs per HP compared to the top of the line Vette which is the ZR1 at 4.7 pounds per horsepower.

The 797 HP figure of the Dodge must be better than the 755 of the Vette.

If I ever have the money (and before I get much older than the 62 I am now) I would start with a 1989. Why an 89 ? Because that is the cutoff year for one of the classes in the Optima Ultimate Street Car Challenge. Then with a cage put in it, knowing that the cage should include connections to the halo and the windshield column (GM really effed up when that high ranking GM'er said it had to have a targa top, instead of the t-top it was designed for) OR refab the targa top in real Fixed Roof Coupe with the halo/windshield tied together with metal welded to the frame (along with a cage for safety, even though it adds some weight, what is your life worth).

Then World Products makes a block that is standard small block Chevy on the bottom end (so relatively inexpensive internals) and uses the standard motor mounts bolts to the trans in a standard manner, etc. The top is is adapted to use LS heads and intakes. So you go with a good set of LS heads and recently developed superchargers (that sit between the heads) and you can build a very potent engine.

Upgrade to C6 brakes, there are adapters (and how tos on CF) or even Brembos or other brake systems for C4's available now.

A rear suspension, Banski in fact, like I have for my '96, del-alum for the front end from Global West and with some very careful shopping and doing most of the work yourself, you can build a very very killer car that will embarrass most (not all) but most new cars, both in a straight line and on the twisty roads.

C5's are the same, with their prices having tanked in the last 2 years. A platform to build on.

The issue is that so many people today that have these fast cars, the only hard work they have done to get them is sign the paperwork and strain their finger. Their is a guy that shows up at one of the local cruise-ins that brags about his horsepower and such, but he has done nothing to get there other than sign the paper.

I guess I am just old-school.
 
I keep telling people how great a bargain they are. Over on CF, I put together a post showing how easy it was to make a C4 Corvette outperform a lot (not all) but a lot of today's "muscle" cars because of the power to weight ratio and the fact that the basis in cost is so much less.



Yes, but it is easy to outdo them, but "perceptions" are what people go on. Take the top of the line Challenger, it has
797 HP and 707 LB-FT of Torque. From what I can see on the web, its weight is 4443 lbs. That is 5.57 lbs per HP compared to the top of the line Vette which is the ZR1 at 4.7 pounds per horsepower.

The 797 HP figure of the Dodge must be better than the 755 of the Vette.

If I ever have the money (and before I get much older than the 62 I am now) I would start with a 1989. Why an 89 ? Because that is the cutoff year for one of the classes in the Optima Ultimate Street Car Challenge. Then with a cage put in it, knowing that the cage should include connections to the halo and the windshield column (GM really effed up when that high ranking GM'er said it had to have a targa top, instead of the t-top it was designed for) OR refab the targa top in real Fixed Roof Coupe with the halo/windshield tied together with metal welded to the frame (along with a cage for safety, even though it adds some weight, what is your life worth).

Then World Products makes a block that is standard small block Chevy on the bottom end (so relatively inexpensive internals) and uses the standard motor mounts bolts to the trans in a standard manner, etc. The top is is adapted to use LS heads and intakes. So you go with a good set of LS heads and recently developed superchargers (that sit between the heads) and you can build a very potent engine.

Upgrade to C6 brakes, there are adapters (and how tos on CF) or even Brembos or other brake systems for C4's available now.

A rear suspension, Banski in fact, like I have for my '96, del-alum for the front end from Global West and with some very careful shopping and doing most of the work yourself, you can build a very very killer car that will embarrass most (not all) but most new cars, both in a straight line and on the twisty roads.

C5's are the same, with their prices having tanked in the last 2 years. A platform to build on.

The issue is that so many people today that have these fast cars, the only hard work they have done to get them is sign the paperwork and strain their finger. Their is a guy that shows up at one of the local cruise-ins that brags about his horsepower and such, but he has done nothing to get there other than sign the paper.

I guess I am just old-school.
Road race track is interesting OK.
Living in Illinois there is just the Autobahn at Route 66.
Need over $80,000 cash to join to race on the track with your car.

Streets are Free to race on.
Legal at Drag strips & way less money here at $15 to have your checked by Tech officials & race.
Love My Corvette. Being a convertible it can only run 13.5 ET.
So many setbacks to make super fast & legal. Exceeds the value its worth. Just not worth it.

My 1970 TA is a much better drag car. No cage it can run to 11.49 ET Legal.
 
personal opinion and some field experience, here no doubt ,
yet having built and modified several dozen c4 corvette engines,
and having done several transmission swaps , related ,too various power levels
, theres a balance to be striven for in a rational street/strip car.
I am personally not all that impressed with the 700 hp dodge cars,
yes power is obviously impressive
but in my opinion styling and handling leave a great deal on the table.
now I also am not impressed with the c5-c6 styling,
but with minor upgrades, handling in both is in my opinion superior to the much heavier dodges,
I like the c7 corvette styling and the drive train suspension and engines have a good deal of potential.
the C8 is yet to be fully revealed so its an unknown.
most of us can,t afford to buy or modify a C7 corvette but the c4 and c5 are in a reasonable price range.
personally as Im sure youve deduced I prefer the 1996 C4 corvette looks and you can very VERY easily ,
modify a C4 with a dozen options like a BBC,4l80E or a turbo an verious ls engines,
and a few suspension and brake and cooling mods,
to run with the dodges for a considerable reduction in cost from the $50K-60K plus the new or year or so old dodge costs.


$5K-$9K for a decent project C4 corvette, roughly $14.6 k for a 775 hp crate street engine
roughly $5500 for a 4l80e with converter and your still under 30k with assorted other required parts

https://www.shafiroff.com/chevy-pump-gas-engine/598-bigdawg-lowdeck.php

https://transmissioncenter.net/shop...anual-performance-4l80e-transmission-level-4/


http://garage.grumpysperformance.com/index.php?threads/the-c4-bbc-engine-swap.151/

http://garage.grumpysperformance.co...s-guys-1000-hp-build-has-some-good-info.1328/

http://garage.grumpysperformance.co...a-4l80e-to-full-manual.5579/page-3#post-80061

https://web.archive.org/web/20040211052117/http://www.montygwilliams.com/

http://garage.grumpysperformance.co...ear-axles-and-differentials.11848/#post-87503

http://garage.grumpysperformance.com/index.php?threads/a-few-ls-related-links.15164/#post-86715

http://garage.grumpysperformance.com/index.php?threads/chevy-ls1-related-info.3918/
 
Last edited:
Oh yes, I forgot the how to's here. No offense intended. I wrote that above in the middle of the night after having to walk the dang dog.

I also, like the '96's. For just a pleasure car, (not the OUSCC I mentioned above) I would really like to have an Artic White with Torch Red and Black interior, but the 6-speed (LT4 :) ). It would be a twin to my '96 LT1 A4. Or even a different interior color, other than basic black. I would have a stripe painted very similar to our current car, but I would add some body components.

I would sidestep the Banski and Global West components and put Super Pro bushings in th A4 car.

Once I get done with our '96, it is going to be a really nice car, for less than 1/2 what a base 2018 Corvette cost.
 
Back
Top