This post will cover a 1963 Corvette body mount repair. When removing the body from the frame on our 1963 Corvette project, one of the body bolts seized into the captive nut and broke off. To fix this problem we needed to replace the seized captive nut. The captive nut was located in the rear of the body, so access to it was relatively easy.
Here is the old body mount with the broken bolt. This is the rear most body mount on the passenger side. You can see that there is good access to the rivets that hold it in.
This is the body mount from the inside of the car. For the body mount repair, all the rivets need to be drilled out and removed.
The body mount is actually comprised of two parts. There is a lower reinforcement plate that is riveted in, and there is a cage nut that is riveted in. The cage nut rivets can only be accessed after the reinforcement plate is removed. Here you can see the rivets to the cage nut after the reinforcement has been removed.
This is the old lower reinforcement, it will be reinstalled after the new cage nut is riveted in.
Here is the seized cage nut from the body mount.
Here is the new cage nut riveted in. The rivets are a standard aluminum flat top rivet that were used in multiple locations on the Corvette. To mushroom the rivet, we used a steel block on the flat top of the rivet and a air hammed with a convex tip to mash the rivet tip. Being aluminum, it takes little force with the air hammer to mash the rivets.
Here you can see the reinforcement plate installed. We bead blasted the plate to remove all the rust and grime and then reinstalled it. From the factory these mounts were all bare steel so painting it is not an option. Now the body mount repair is complete.