v8vette84

This is a taboo topic and I have done some searching and there is very limited info on these cars rotting. Who here has seen a badly rusted or rotted C4 frame? I personally have seen a VERY bad one in a junkyard. I even took a few photos of the rot. Right in front of the driverside rear wheel was completely rotten. That flat spot on the frame where many of you put a jackstand was gone. You could see up into the frame rail going up towards the halo. Hell, I could just about put my hand up into the frame rail. Only on the driver side which was interesting. I could see where the dog bone bracket bolts went into the frame from the inside. I'll dig up pics. I wonder how it rotted out so bad.

On my own 84' I have had to fix some spots under the battery tray where the frame had some small rot holes. Anyone else have/had rot issues?

Everyone seems to think Corvettes can't rust or don't rust easily. This is absolute fiction from what I have seen.

DMITTZ

I'm sure some of the really rough ones that have been abused for 30+ years have some rust. Mistreat anything for long enough and it will wear out.

They cars did have excellent rust protection when new and generally have stood up very well compared to most every other car of that era.

My car has like 130,000 miles up here in Canada and only had one very small spot of very minor surface rust where a jack stand is normally placed in the rear. After a quick clean up and painting that spot is good as new, the rest of the frame was perfect. I'd say generally C4's have very few rust problems but I'm sure there will be the odd abused one that does as they continue to age.

Joe C

my second 90 had some surface rust on the frame, below the battery. for the most part, easy clean up and paint. with living in the NE ohio rust belt, my other c4's, for the most part have been rust free. the only thing significant was on my 85 - the inner driver's door frame where the side mirror mounts. seems water seeps in past the mirror's plastic body gasket and puddles where the two mounting nuts are located. I caught mine in time, and had minimal rot. after a thorough cleaning and rust treatment. used an automotive body sealant, along with a new mirror mount. hopefully it won't be an issue anymore. once that inner door frame is compromised, the only solution is a door replacement.

FostersPerformance

The frames are galvanized if i remember correctly....

Buckeye88

I live in Akron, OH and have an 85 that was originally sold at a dealership in Canton, OH. It has always been an Ohio car. I have the same rot issue described in the first post. Just behind the driver side front wheel well. I posted about it awhile ago, with mixed responses. Most said they had never seen rot like that on a C4. I bought a frame rail section and while I have the car apart for a ZF6 swap, I'm cutting out the rotted section (about 4 inches long and 3 inches up and across the bottom) and once I treat the remaining steel (grind and por15 the inside), have a friend weld in a matching chunk of the section I purchased. The rest of that area is strong so I don't have to have someone who is certified do the work....for now everything is still straight. I did have to take it to a frame shop and they looked it over, took some measurements and told me I was better off doing it the way I am.

Also, just as stated above, the passenger side is factory fresh

Sucks, but at least it can be saved. I was worried I would be looking at extensive frame repairs or finding a rolling chasis.

v8vette84

This was that C4 I found in a local junkyard where I used to live. Insane. Almost like that spot was sprayed with saltwater daily...

Above the hole you can see where it turns back into solid steel. In fact the whole area still seemed pretty strong. Still, I assume that's why it's in the junkyard...

jts90vette

I know this is the C4 forum, but C3's are known for this! If your in the market for a C3 make sure you know what to look for!

NASCAR314

Believe it or not, some people actually drove their C4's in light snow, salty roads, and yes, even on gravel roads! Wet limestone dust and dirt collects in some area's and will cause frame rust. Normal area's are behind both front wheels, remove the front rear plastic inner fender to see this (drivers side right under battery) (passenger side under A/C fan blower) and the rear tends to be in FRONT of the rear wheel openings near the rear jacking points, same area that the brake lines go up into the cover where the ABS unit is located. So brake line rust on driver side and fuel line rust on passenger side, both in front of rear wheels IS a common location and worth a look see if buying a used C4. Not a deal breaker if it's only surface rust. Not a huge problem with C4's but worth knowing. I've had C3's as well, they were definitely more rust prone for some reason.

kael

Looks to me like it rusted IN the junkyard, see the shape? Sort of like it was sitting in a puddle.

v8vette84

I actually asked about it as I was inquiring about parts off the car and they claimed it arrived in that condition. No idea, I just assume there is no reason to lie about that.

mtwoolford

If nothing else, check the battery box area.

My 96 came out of the greater Sacramento / San Juaquin Valley in California where rust is (usually) not an issue. It had some minor surface rust below the battery box, which cleaned up nicely without any structural issues. Other than that, no rust. (one plus for living in California ?).