Hi all, I've got a 78 SA that has bad rust in the hinge pillars and lower windshield sections. I'm in the process of replacing the entire birdcage structure and I thought it would be a good idea to document the whole process here.

I only started taking pics after I got the front clip and firewall removed. The method for removal is pretty basic, drill out any rivets and then use a heat gun to soften the bonding compound and then using a rubber mallet and a putty knife and 5 in 1 tool start separating the bonded joint with as little damage to the glass as possible.



As you can see from the below pictures, the rust was extensive. If I'd have just patched the upper sections I knew were bad, and then hung doors, there is no way way would have stayed level. I'd have been lucky if they didn't come off in y hand the first time I opened them.



Oddly, the floors are in great shape. had a bit of surface rust but nothing catastrophic.







I've sourced a new bird cage out of a 76 locally. There are a few minor differences but nothing that can't be cut off the old cage and welded to the new one. As of last night I have started working on removing the rear clip. I managed to get the back glass out without breaking it so now I should have better access to the inside bonding strips. Right now I've got the body on the lift but without the front clip it's very back heavy so tonight I plan to come up with a way to support the wight of the rear clip with my engine hoist. I'm thinking of something like a truck bed removal fixture inserted through the rear window opening. This should support the rears weight as well as make it easy to move in and out of place when the time comes to reattach everything to the new cage. I'll get some more pics tonight as I make progress.

When this all began, I was going for a simple restoration. Obviously it's gone a little crazy at so I'm kicking around the idea of performing some body mods while I've got every thing apart. I'm almost 100% that I want to add fender flares. I'm leaning towards a set of l88 front and rear flares but haven't nailed down the manufacturer yet. My big question now is, do I want to convert the t-top to a convertible? I'm also considering grafting on a rear deck from a 77 or earlier to get the vertical rear glass instead of the bubble glass. I'm not sure how the rear fender design changed over the years so I'm unsure about how hard this change would be. I'm not sure if the rear deck lid dimensions on a 77 or earlier would be close enough to the 78 to make this feasible. I do know it's possible to make it a convertible which I'm seriously thinking about. No matter which way I go it'll be an adventure and I'll do my best to document it.

Tom

 

Where are you located. It would help with suggestions and if any member in your area might have parts or whatever to help you with you project.

 

Tom, this is a great project and very ambitious! Many cars need, and are worthy of this repair. Thanks for sharing and the excellent photos so we can follow along.
Greg

 

Not many people would attempt this, my hats off to you, most people would move on to another car. Great that you can save another corvette.

 

 

I'm in North Florida near Gainesville. I've also update my signature to show this.

I bought this car back while I was in college and it's a labor of love at this point. I enjoy doing stuff like this so the economics don't really come into play. I'm sure I could buy something easier to get going but it's the principal of the thing now. Nothing ventured nothing gained.

Yeah, I've always been more stubborn than smart.

Been in the shop pretty much every night this week working on removing body panels. It's slow work trying to do as little damage as possible. It's actually a pretty simple process, apply heat and gently separate the joint with a putty knife and a hammer rinse and then repeat As of last night, I broken the bond between the fenders and the lock pillar panels and started drilling out the rivets holding the rear clip to the birdcage structure. The whole operation was a bit tipsy on the lift so I through together a simple lifting jig to help stabilize everything. This should also allow me to control the rear assembly when I finally separate the adhesive joint and reduce the risk of it falling on me as I work under it.









I so far the worst joint to separate has been the drivers side lock pillar to fender joint. No matter how much heat I applied, the joint just didn't want to cooperate. The putty knife kept sliding out of the joint and into the panel. Once I get the fender off I'll try to salvage the section still bonded to the fender and try to glass it all back together.





The passenger side was much easier and came apart with no damage at all. I'm pretty sure I need to pull the fenders before you can remove the lock pillar panel there are a number of overlapping joints in this area so the order of operations is pretty critical.




The original plan was to separate the entire rear clip as a single assembly but it's so large and heavy that I think I'm just going to take it down to it's individual panels. This will also make reassembly much easier for me to handle by myself. I'm also all but positive I'm going to make this coupe a convertible so the rear deck is going to have to come off anyway.

This is the birdcage assembly I bought. It has 1 visible repair and it's been blasted and painted with POR 15 so it should be good to go. The floor is riveted and spot welded in place and I think I need to move some brackets over from the old cage so I'll be grinding off some paint to weld everything in place. Once done, I'll give it a good sanding and hit it with a heavy topcoat of chassis black.





So far I'd say the project has been pretty simple. taking the car apart isn't hard, it's just time consuming. The factory assembly manual helps a lot. I think reassembly will be pretty straight forward. It seems like most of the parts reference pretty easily off the parts they attach to and those parts that attach to the cage are all at least partially attached with rivet holes so you have simple locating pin to reference off of. Pretty sure I'm going full custom on the build. Probably going to make it a convertible and add fender flares front and rear as well as add a custom rear bumper with spoiler and find a way to remove the stock front bumper bumperettes. Next step will be to pull fenders and remove the rear deck as an assembly. I'll try to knock those out this week because I'm traveling ext week for work.

Thanks for reading,
Tom

 

I will never complain again about changing body mount bushings. After seeing this amount of work.

 

Has anybody created a build thread detailing changing their coupe to a convertible?

Tom

 

Wow..great stuff. I am curious where your car has been stored all these years after seeing that extensive rust in the bird cage? My 78 has been almost exclusively garaged for the last 30+ years with no driving in any rain and rarely washed with water. I sure as heck hope that my car does not have that amount of birdcage rust...........

 

 

Wow that gives me knots in my stomach, you got some nuts going this far!! You will definitely know what you have when its done, keep it up.

 

Thanks for the response..I figured it must have been outside in a warm humid environment to have that much damage. Mine has a decent amount of surface rust on the frame but nothing major......

 

I know. I get hives just thinking about doing a 5-speed conversion on my '71.

Wish I had your skills, Sir (and your shop, lol).

 

I've been busy with other things over the past few weeks but I did manage to squeak out a little shop time here and there. My main focus has been removing enough panels to to allow me to remove the rear clip. I wasn't sure how far I needed to disassemble the rear section to allow it to be removed. The key piece standing in my way was the door lock pillar panel. It is sandwiched in between a number of panels and this is what really determines how far you need to assemble the rear to get it to drop free. The next pieces to be removed were the fenders. The passenger side went pretty well, all the joints separated at the bonding strip without much fight.







The drivers side however did not go as well. I'm not completely sure this panel had not been replaced in the past. It was adhered very well and the joints were very tough especially the one at the bottom of the fender where it attaches to the lock pillar panel. I ended up pretty much destroying the drivers rear fender and the lock pillar panel. I'm planning to put new fenders on it so no great loss there, but the lock pillar panel was a disappointment. It appears the lock panels bonding seams were pretty heavily body worked when installed so I may be able to salvage the broken panel and cover my sins with Vette Bond filler.




I had planned to remove the rear deck to allow removal of the lock pillar panels, but with all the seam separating I had done on the passenger side, I was able to wiggle the lock pillar panel out from between the seem it shares with the deck lid and the bonding strip that the fenders adhere to. I'll probably still end of removing the deck lid to make reinstalling the rear clip easier and allow me to have more adjustability when I hang panels. With the lock pillar panels out of the way, the rear assembly could come off as a single unit. It's kind of surprising how little holds these panels to the rear of the birdcage. there were maybe 10 aluminum rivets, a few gobs of panel adhesive and a metric crap ton of seam sealer. Once the rivets were drilled out, all it took was some gentle persuasion with a 2' pry bar to break her free.








I don't have any pics of it yet but I've started drilling out the spot welds that hold the floor pan in but I'm doing more damage than I'd like so I'm having to reassess my approach. Drilling the spot welds is easy. The problem comes when separating the floor pan from the rocker panel. The rocker panel is much stronger than the floor pan sheet metal so when you try to break the bond between them, the floor pan bends and the rocker doesn't. This is distorting the floor quite a bit and I'm worried I won't be able to get a good fit when I weld it into the new birdcage. Since the existing cage is trash anyway, my new plan is to cut the cage around the floor assembly and remove it that way. Once free from the car I should then be able to remove the remaining cage material without damaging the floor pan.

I've also nailed down my plans for the car. I've always hated the rear bumper of the later years and I'd kicked around the idea of adding a spoiler to it or maybe adding one of the later 80's style bumpers but since I want fender flares anyway, I've made my mind up to go with a rear chrome bumper conversion and fender flares from Custom Image Corvettes. I looked at a few options for doing a front chrome bumper but most of them looked odd to me so I've decided to modify a 73-74 front bumper to fit. I had also played with the idea of making it a roadster but the cost of soft top parts is just too high. Someone could make a killing if the could find a way to make the new convertible frames for just $1000 vs $2000.

The weather here is finally cooling off so I hope to make some more progress over the next few weeks. I'm waiting on some supplies and I can't afford the fenders and rear bumper yet so it's going to be a little while before I can start putting stuff back together. In the mean time I'm going to start patching panels that were damaged during the removal process.

Thanks for reading.