C3 Windshield Frame Rust

[Michael B.]

After recently completing my 72 chassis restoration I've begun work on the body. I knew there was rust in the upper corners of the windshield frame so I carefully removed the original windshield today. After cleaning out all that old adhesive I spotted rust in the lower right corner down under the fender. I guess this is technically the birdcage instead of the windshield frame. I'm looking for suggestions on how best to repair this. I don't think there's any way it could be cut out and re-welded with the fender in place. Paint is not a concern as I intend a full re-paint.

Should I remove just this one fender, and if so, where to make the cuts? Should I consider removing the entire front clip and leaving the fenders as one piece? Is there another option?

Thanks,

Mike

[Joe L.]

Re: C3 Windshield Frame Rust

After recently completing my 72 chassis restoration I've begun work on the body. I knew there was rust in the upper corners of the windshield frame so I carefully removed the original windshield today. After cleaning out all that old adhesive I spotted rust in the lower right corner down under the fender. I guess this is technically the birdcage instead of the windshield frame. I'm looking for suggestions on how best to repair this. I don't think there's any way it could be cut out and re-welded with the fender in place. Paint is not a concern as I intend a full re-paint.

Should I remove just this one fender, and if so, where to make the cuts? Should I consider removing the entire front clip and leaving the fenders as one piece? Is there another option?

Thanks,

Mike

Mike------


The windshield frame is part of what is known as the "birdcage".

If the corrosion damage was limited to the upper and side rails of the windshield frame, you might be able to repair it yourself. It would be difficult but if you're really good, you might be able to do it. If it's more extensive that that, and it sounds like it is, the repair is going to be much more difficult and it's going to take someone with a lot of experience to do it right. It's also likely going to be expensive. It might even be more extensive than you've so far identified.

How is the frame on this car?

[David H.]

Re: C3 Windshield Frame Rust

Michael,

What is the condition of the #2 body mounts on the birdcage? (Bottom of Hinge pillar) Are they severely rusted as well? If so, then the birdcage most likely is rusted in places you can't readily see.

Dave

[Michael B.]

Re: C3 Windshield Frame Rust

Joe & David,

The vertical side pillars on the windshield frame are both good. The rust is confined to both upper corners and some on the upper horizontal piece. Also the lower body mounts and vertical channels of the birdcage are rust free as far as I can tell. The entire interior of the car has been removed so I can see quite a bit of the interior of the birdcage. The rust I discovered today was quite a surprise. The chassis frame is in excellent condition. Absolutely no rust anywhere else that I can see.

I realize this will be a big job to repair correctly, and would best be done by an experienced shop. But, this is a base engine automatic car that probably won't ever be worth more than $30K. I'm not willing to invest $15 - 20k in this repair, and re-paint. Based on my conversations with some restoration shops the paint alone starts at around $12k. I'm simply going to have to do as much as I can myself, then call in the Calvery as a last resort.

[Russ S.]

Re: C3 Windshield Frame Rust

Is the rust on both sides or just one side? If one side, as much as I hate doing it I think the best option is cutting the fender out behind the firewall downward and then backward to the front edge of the door.

[Patrick H.]

Re: C3 Windshield Frame Rust

Calvery

Cavalry is the word you intended, for the trained troops which historically were on horseback. In modern days, they're in tanks.

Calvary is the hill outside Jerusalem where Jesus was crucified.

Calvery is not a word.

Brought to you by your friendly JG text editor.

[Michael B.]

Re: C3 Windshield Frame Rust

Patrick,

You are so right. Being a former Army Officer I know the correct spelling. I think it must be the tears in my eyes after finding the rust.

Mike

[Michael B.]

Re: C3 Windshield Frame Rust

Russ,

The rust is on the right side only. It's about two to three inches below the upper edge of the fender.

I'm curious where the pros would make the cuts to minimize the damage. My initial thought was exactly what you suggested.

Mike

[Bill L.]

Re: C3 Windshield Frame Rust

On my 70 Convertible my frame was spotless as were all the body mounts and remainder of the bird cage. I had some minor rust on the windshield header and upper corners of the windshield frame likely from washing. Keep in mind I had zero rust down at the base of the windshield frame. I used POR 15 and was very pleased with the results. If the rust is localized to the right side, consider using POR15 putty and rust treatment. You can mold the putty to whatever shape you need and basically fill the holes with the putty. Even pretty big holes. This assumes that 80% of the metal is still intact and that appears to be the case from the picture IMHO. Go to the POR15 website for details. First treat the inside of the windshield frame with POR15 as best you can. Follow instructions exactly. I had a pretty rusty GTO convertible and the POR 15 worked very very well.

If this was an LS6 maybe you cut the fender out and do the repair differently.

If the frame was rusty I might suggest otherwise as well. Safety first.

Kind Regards,


Bill

[Gene M.]

Re: C3 Windshield Frame Rust

Just a thought, but can you get at it from the back side with the entire dash removed? If you are concerned with retaining original structure fill does nothing except cover up the holes. Possible metalized fill such as Deacon may add some structure if incorporated with carbon fiber matt. Maybe access is better from inside under the dash area. I would be concerned with a lot of welding changing the position of the windshield posts frame. Experienced guys with TIG background can sometimes do wonders.

[Michael B.]

Re: C3 Windshield Frame Rust

Bill,

Thanks for the POR 15 idea. I'll check it out.

Mike

[Michael B.]

Re: C3 Windshield Frame Rust

Gene,

I thought of access from the inside but there is the inside portion of the birdcage structure that would need to be cut AwY in order to access the outer portion that has the rust. I think I would compromise the structural integrity of the birdcage by doing this.

I think I should probably have a professional look at this and get an estimate on repair. I might be pleasantly surprised. At least I would know how to best approach this. You never know, with the rest looking so good he may even advise doing nothing.

Any ideas who might have experience with this type of repair. I'm in the San Antonio area so a Texas shop would be my first choice.

Thanks,

Mike

[David H.]

Re: C3 Windshield Frame Rust

Michael,

You might want to check out "Chevrolet Corvette Restoration Guide",by Lindsay Porter, 1996. ISBN 0-7603-0325-8 (Should be available Barnes & Noble etc.) Page 56-57 - starts at image WR17. This has photos and a description as to what is involved with this particular birdcage repair.

Dave

[Michael B.]

Re: C3 Windshield Frame Rust

Dave,

Thanks for the tip. I happened to have a copy of that book. It took me awhile to dig it out but it's a perfect reference on how to do this repair. It looks like I'm on my own with this as neither Chuck Anderson in Fort Worth, or Tom Ames in Longview know of anyone that does this type of work.

Thanks again,

Mike

[Jim T.]

Re: C3 Windshield Frame Rust

Michael I have a 1970 Corvette coupe that I personally have done rust repair to it's windshield frame. Replaced the top center piece and both of the end corners. I consulted a Corvette painter/body experienced man that worked at a dealership and had his own Corvette paint/body shop. He showed me where to cut my top fender on both sides to remove the fiberglass to replace the complete pieces on both sides you show in you picture. This man had previously replaced my 70's front clip years before due to a front end accident and repainted the front. The front clip does not have to be removed for the parts replacement I did. I did this repair in 1990 and all the new parts were available from my local Chevrolet parts department. Some of the parts have been reproduced and were available lately but not from the Chevrolet parts department. There is a fiberglass fender support that is mounted to the lower rusted part you show. Over time it does not seal very well to this piece even though the fender is on top of it. Under this fiberglass fender support and in the lower metal piece there is a round hole in this piece and water can enter your Corvette. Even the new pieces I bought from the Chevrolet parts department still had the same hole. The body man I mentioned welded this hole up for me before I installed the part. I can send you pictures of my rust repair if you send me an e-mail.