C3 Body to Birdcage

[Tom R.]

As many others have experienced, my 70 has rust issues on the birdcage. Now that the body is off and on a dolly, I get the full sense of what needs to be done. Looks to me like the only thing worth saving is the middle part of the rocker channels. With that said, given the time, money, patience, and enough alcohol, I'd replace the entire cage. Assuming I do lose my mind and proceed, could the body be detached and remain in one piece in order to "insert" a rebuilt cage underneath? And other than the rivets along the rocker channels, door lock pillars, and windshield frame, is there other bonded areas that would have to be broken? It looks like there may be material under the #1 mounts - is this some sort of epoxy between the rocker channel and body panel? Are there other areas where the cage is mated to the body with other than rivets?

[Chuck S.]

Re: C3 Body to Birdcage

...Assuming I do lose my mind and proceed, could the body be detached and remain in one piece in order to "insert" a rebuilt cage underneath? And other than the rivets along the rocker channels, door lock pillars, and windshield frame, is there other bonded areas that would have to be broken?...

Very doubtful in my opinion. You will be "certifiable"...but to be truly admired if you do finish the task.

Yes. If it's the 70, study the AIM beginning with UPC 1, Sheet A12 through B13. I believe Item 87 referenced on several sheets is bonding adhesive.

[Joe L.]

Re: C3 Body to Birdcage

As many others have experienced, my 70 has rust issues on the birdcage. Now that the body is off and on a dolly, I get the full sense of what needs to be done. Looks to me like the only thing worth saving is the middle part of the rocker channels. With that said, given the time, money, patience, and enough alcohol, I'd replace the entire cage. Assuming I do lose my mind and proceed, could the body be detached and remain in one piece in order to "insert" a rebuilt cage underneath? And other than the rivets along the rocker channels, door lock pillars, and windshield frame, is there other bonded areas that would have to be broken? It looks like there may be material under the #1 mounts - is this some sort of epoxy between the rocker channel and body panel? Are there other areas where the cage is mated to the body with other than rivets?

Tom------


If you succeed in accomplishing this, it will be very close to succeeding in bringing someone back to life after they have died.

[Terry M.]

Re: C3 Body to Birdcage

I know of two people who have done this -- and both say "never again!" But it can be done with a great deal of patience and buckets of money. One fellow had his car body supported on a "bed plate" so that the alignment would come out "in the ball park" when complete. Since most, probably all, of us do not have a "bed plate" at our disposal, you may conclude, and you would be correct, that this fellow had some very expensive professional help.

FWIW: The only place I have seen "bed plates" are Bowling Green Assembly Plant, and the NASCAR garages. I am sure some large machine and fabrication shops also have them. And I think I would look for a fab shop if I were thinking of taking on this kind of task.

[Tom R.]

Re: C3 Body to Birdcage

If somebody would give me a hug and tell me it's possible to separate the body in one piece, I may go for it. Call me crazy, but hey how bad can it be? I may have seen that on this site before.

[Edward J.]

Re: C3 Body to Birdcage

Tom, one word - Donor

[Rich P.]

Re: C3 Body to Birdcage

I have done this on midyears as well as on 68-up Some were complete and some were partials.
The front hinge pillars as well as the rear striker pillars go through the body. You will have to peal fiberglass of all 4 sections as well as cut the donar bird cage into several pieces and weld the cage back together once slid back in place. Once you lay it out you can decide if you want to do more "pealing" or cutting.
You can make a jig that will keep the alignment (same as a fully adjustable body dollie). Most of the filler beween the bird cage and fiberglass is sealer. They did not have the technology to bond steel to fiberglass untill later thats why you have fiberglass pieces riveted the steel bird cage and THEN the fiberglass bonded to that.

Oh I forgot to ask is this a coupe or convertable. For your sake I hope its a convertable otherwise double the time.

Rich

[Harmon C.]

Re: C3 Body to Birdcage

Many cars are parted out and the birdcage is the last to sell. Find one that is not rusty if you can and use it complete or for parts. I have been to a few Corvette yards and they all have lots of birdcages.

[Tom R.]

Re: C3 Body to Birdcage

Mine is a convertible and thanks so far for everyone's input. I will try to locate a usable birdcage beforehand. Or before considering creating one from the parts available. Although I have not seen the door lock pillar support on anyone's site for sale. I am confident I can keep/maintain the original birdcage's overall dimensions during assembly in order to recreate the template. I'll be making a final decision this weekend as it's time to get off the pot so to speak.

[Wayne W.]

Re: C3 Body to Birdcage

Not a job for the faint of heart, but it can be done. If you are going to change the whole cage, I would say the easiest way would be to take the front off as one piece, then remove the rear. After the rear section is removed, disassemble the small parts from the bird cage to expose it. Be careful so that you can reuse the bonding strips and other parts. I wouldn't cut up a good cage unless you are doing only certain sections. It would be a much better repair to use the whole cage. Good luck.

Similar job on a midyear.

[Patrick H.]

Re: C3 Body to Birdcage

Take a look at this site:

http://www.corvette-restoration.com/

He did a heck of a lot of work on his birdcage and you can learn a lot from it.

[Lynn H.]

Re: C3 Body to Birdcage

CERTIFIABLE??? I think I fit into that category. I have done about a half a dozen of these "total birdcage" repairs, from the top of the windshield frame to the center of the rear bulkhead. I am currently doing a convertible of my own. The best way I have found is with a good "core" from a donor car, that can be drilled apart at the spot welds. I prefer this to using the NOS pieces, as I have done them that way also. The used ones seem to be much easier to line up the doors and windshield frames, than with using new parts (either NOS or reproduction). The front clip has to be removed. This job is quite extensive, and not everyone is willing to take this on. The convertibles are much easier to do as you do not have to deal with the halo on the coupes. I have over 100 photos of this being done if anyone would like to see some more drop me a PM. Here are a couple from a 69 BB car I did a couple years back. I have a fixture I made from an old boat dolly that works real well for installing.
Lynn

[Chuck S.]

Re: C3 Body to Birdcage

CERTIFIABLE??? I think I fit into that category. I have done about a half a dozen of these "total birdcage" repairs, from the top of the windshield frame to the center of the rear bulkhead.

Yes, Lynn, you would be "certifiable" too if you approached this problem in the manner his question suggested: "...could the body be detached and remain in one piece in order to 'insert' a rebuilt cage underneath?"

You and Wayne have broadened the answer to his question into the only logical, albeit incredibly work-intensive approach reserved for dedicated five-hammer craftsmen. Perhaps your answers will help Tom to better understand the scope of his task.

This repair will require boundless optimism that doesn't fade and/or bottomless pockets. But, I wouldn't walk away from an otherwise bonified big block either...I would consider another, er, approach.

[Tom R.]

Re: C3 Body to Birdcage

Thanks Patrick, the website you linked shows and answers just about everything.

[Jack H.]

Re: C3 Body to Birdcage

My '71 was an Ohio/Illinois/Michigan car. It had BAD rust/rot damage and I 'fixed' it with body-on-birdcage repairs. No, it was NOT an easy job, but it can be done, mon!

When the body was originally lifted off the frame, the RH frame rail fell apart in three discrete sections. The LH frame rail broke into two pieces. There was a snapping/popping sound accompanied by a dust storm of iron oxide as the bird cage's sill rails disintegrated and the body began to fold, tip to tail... Not good!

A donor frame was used to implement the restoration. Portions of the bird cage here judiciously 'tapped' to determine where useable metal was and where it wasn't.

Then, bird cage components from a donor car were strategically cut and welded onto the existing, useable, reminants of the car's original bird cage. These included:

(1) The WS frame
(2) RH lower and rear sill rail
(3) LH lower, rear, and a portion of the front upright sill rail

The work was done WITHOUT removing the un-hit factory original fiberglass panels. But, some areas were VERY tricky to execute the welding in...

At times, dry ice and wet towels were used to stop-gap heat propagation from the welding process and a fire extinguisher was strategically located CLOSE to the car during the 'grafting' process.

When this/that section of the bird cage was cut and removed, we gained access to the inside surfaces of the remaining bird cage members. Compressed air was used to blow out existing scale and stop-rust inhibitor was LIBERALLY sprayed into these sections prior to the donor sections being final cut and welded in.

Since, I've logged +60K miles on the car and it's SOLID. But, such 'heroics' truly are a labor of love. If this hadn't been my uncle's car, it probably would have been stripped for parts and permanently 'retired'...