Grand National Aerocoupe PROJECT - Page 7


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To make the GN Aerocoupe look even more authentic, I installed the rear cross brace that's installed from the factory in all Monte Carlo SS Aerocoupe's.

Here you see the brace from a Monte Carlo Aerocoupe positioned behind the rear seat of the GN. It sits diagonal to help body flexing in the that area.


The first thing was to remove both original Grand National metal plates (in my hand) so the cross brace could be positioned in place. I used a spot weld remover in a hand drill to cut the spot welds out. I only cut deep enough on the bottom of the original GN plate to get the plate loose but not cut through the floor of the body itself. You can see the bright metal circles where the spot welds were cut out. On the upper part of the GN plate, I cut through the original GN metal so I could plug weld it to the Monte SS cross brace. When looking through the trunk, you won't be able to see where I welded it in.


Here is the surface sandblasted out before welding.



Here is the Monte SS Aero brace positioned in place and ready to be plug welded.. It was a pretty easy job to do and it makes it look like it's factory installed!


Welded in place...



This picture shows where all the holes are drilled.



Here you can see that there's a brace that rivets to the body of the car and then the package is rivets to it.



Since I wanted to keep the original holes and not drill new ones, I temporarily attached the underside brace to the package tray. I then placed the whole package tray on top of the car as if it was already attached. I marked the body of the car at the end of the brace with a line so I could later use the brace as a guide to drill new holes in the body. This will allow me to drill through the brace using the original rivet mounting points. Talk about OCD...jeez!


Here are all the holes drilled in the body.



Here is the brace riveted in place.


The Monte Carlo SS Aerocoupe originally had the rivets installed from the top going through into the truck. Since rivets are usually sharp and flare out when they are installed I chose to install them from the bottom upward. This will keep things you throw in the trunk safer (as well as your hands) from getting scratched.




Now that the brace is installed to locate the package tray on top of the trunk area of the Grand National, I've drilled some holes in the body to attach the package tray in the sides. These holes will act as "spot welds" when they are welded from the bottom.



Welding inside the holes from the bottom-side to the package tray will hold everything in place permanently. Welding in the holes is called "plug welding"



Before welding in the tray, I put some seam sealer beneath it to seal it from possible water leaks. Then, I used two screwdrivers positioned through a couple of rivet holes and clamped the tray down to the body.


Once I clamped the package tray down, I installed rivets across the center of the package tray where I had already riveted the underbrace. Once I got that finished, I drilled out the rest of the rivet holes in the body of the GN at the front of the tray where the factory speakers sit. Then I riveted that part of the try to the car. A total of 40 rivets for the entire tray!


Getting ready to plug weld it in permanently.



I still have to clean up this seam area up before painting. Tried to make it look factory.

While I was adding seam sealer to the package tray, I went ahead and put in on the rear of the car also.


I also removed the front clip of the car to gain access to the seam sealer in the firewall area. This also allows me to clean up and paint the inner fenders.



Last updated June 17 2012