This must be a common question but I wasn't able to find the answer with the search function.

When evaluating a car for purchase, what is the best way to determine birdcage rust? Obviously you can't take off the windshield trim on a car you don't own, but maybe there's a trick to figuring this out. Ideally there would be a way to determine possible levels of deterioration (no rust, little rust, some rust, etc.).

 

remove the kick panels in the footwell area. that lets you see the bottom of the bird cage around the body mount bolt.

usually if you have some rot in the upper. cage area, you will either see rust falling down into this area, or possibly rust here from water leaking down.

 

You can also look through the windshield along the outer edge, by the VIN tag and in the same area on the passenger side. Any rust in those areas and in the kick panel area Tiger Joe mentioned likely mean you have a bigger issue in the windshield frame.

 

As others stated, if you see any rust around perimeter of windshield, through the glass, most likely there is a lot more beneath. If there is a lot of flakes in the A pillars, underneath the kick panels, it comes from above. They almost all have rust issues, if the cars were driven at all. I laugh when people talk about rust free C3 Corvettes. And that includes the high priced "rare" Corvettes at con job / high dollar Corvette specialty shops. You just pay more money for that rust.

 

I am a newbie, but found this video helpful:


especially the info at the 6:30 min mark, i had not seen this info posted elsewhere

 

That's a good video showing all the areas of concern – impressed that he even addressed the radiator support. His car has had a spray can chassis "restoration", so it's not really representative of most cars out there. Most likely you'd see a lot of surface rust scale, especially on the rear kickup around the gas tank. Good info nonetheless, thanks for passing the link along.

 

That's an interesting point. With a 50 year old car you would expect some rust to be present.

I guess my follow-up question is how much birdcage rust do you tolerate before saying no to the purchase? This is probably subjective but maybe there's a "buyer's rule-of-thumb".

 

From what I understand, this requires removing the four sill plate screws, then removing the sill plate. After that, will the kick panel just come out or are there additional fasteners/tabs that hold it in?

 

Put a white towel in the foot wells under the dash. Open and close the doors several times and check the towel for rust flakes. This gives you an idea on whether to dig deeper or not.

 

If there are not speakers in the kick panels you can use a flashlight and look through the speaker holes - the small ones and see into the birdcage to frame mount - if you see lots of green that's a good thing... lots of rust not so good.

 

kick panels are secured in place with a friction fit (ie slides in and out). the passenger kick had one spring to remove. very easy process that even i could do...

 

To clarify for anyone reading your words as an absolute: I'm assuming by green you're talking about the zinc chromate primer; be aware that the factory also used black primer in this area, so the absence of green is not indicative of a repair/repaint and deeper potential problems. However, to your intent, in either case scaly rust is no good.

 

I suppose it all depends on your comfort level to repair it properly. I'm not a welder or body expert, so for me rust that is swelling, blistering, and flaking the structure would be cause for concern. If you can push your finger or screwdriver tip into it and it feels and sounds crunchy, that's too much.

 

good video but OMG the jack placement scared the hell out of me!!!!

 

Throw some new batteries in your mag light and go around the window real good. For me upper and side window frame doesn’t scare me , but body mounts do , I don’t want a body off project

 

I inspected a 72 454 project car back around early 2000 that was in a warehouse, behind the seats just aft of the T-Tops the carpet was full of rust flakes. Took all of 5 mins to know this car was a rust bucket.

Short of seller removing all the interior trim panels you are not going to know the full extent of the bird cage condition. However, you can inspect a car bumper to bumper and gather enough information to make an honest assessment of the overall condition of the car from a rust standpoint. You can also add in any anecdotal evidence of the cars past history to use as a gauge of how it was stored or maintained.

There is always going to be rust present just depends on what type of rust. Surface rust on the chassis frame for example is no big deal but if I was inspecting the frame and found exfoliation type rust I would be looking harder in other areas. You can do a pretty through inspection these days with a good high powered flash light and a Bluetooth Borescope or I guess they call them Endoscope.


If unsure pay someone to inspect the car because buying a bad birdcage car is an expensive lesson in life. Now having said that if the price is right just drive it and suck the water out of the floorboards after it rains.

 

Concur, i bought a borescope a few weeks ago and did exactly what was suggested

 

I crawled over and under every inch of mine before I purchased it.
What I found was no rust in any of the areas I could see without asking the owner if I could start removing kick panels or dissecting any sections not visible.
I just assumed that, if needed, I would have to repair or replace a birdcage as part of my restomod.
After I purchased it, I removed the kick panels and found the area had very little surface rust and nothing more.
I still have concerns about that hidden rust around the windshield, but I haven’t seen any flakes or other bad signs in the five years I’ve owned it.
BUT, it’s still in the back of my mind that once I remove the windshield frame and t-tops, I may find some repairs are needed.
Any classic car you buy, will have some degree of rust you will need to deal with.
Just think about all the rust issues you could find in a 50 year old steel body classic.

 

You are spot on - my car had very little rust on it and the kick panel area was incredibly clean for a car 50+ years old. In fact, I could see no real surface rust even in the windshield post area (looking through the windshield).
But - when I removed the top windshield trim, I discovered some rust in the upper windshield frame corner - not bad but I do want the driver side upright replaced and a new one welded on. Point is, even the best of C3's will
have some rust concerns, it's just a matter of how bad. Realistically, how much could you expect from cars 50+ years old and (at least at some point in life) used in rain and bad weather? A car from the 60's would have had
to have been hermetically sealed to have no rust at all...

 

Surface rust is a non-issue. Unless the car has been in a museum from day-one, it will have some measure of rusting. But when you spot areas on a rusty surface that is forming raised areas (ie, 'bubbles'), then the rusting has progressed into the steel member. You can use a medium/large Phillips screwdriver to firmly jab into a rusty surface. If the tool actually pierces the metal, you have big problems. If the part feels solid when jabbed and rust shards don't flake off the surface, there is still adequate part integrity.

Your best approach would be to inspect several 'for sale' cars so that you can get a feel of various rust conditions...BEFORE you consider purchasing a car. Such experience will provide some level of confidence that the car you finally purchase will not be a 'rust bucket'.

Lastly, "When in doubt, walk away." Trust your gut. If it doesn't feel right, pass on the car. There are lots of good cars out there; be patient and the right car will come to you.