I’ve always said the FoxChassis Mustang is just a Coke can with frame rails. I spent about 5 years building up my 88 GT in the late 90’s early 2000’s and the shop that helped me build it fixed nothing but Mustangs. Seeing some of the damaged cars made me come up with that phrase and realize that extra bracing for this light little flimsy chassis was a must. The standard option for the SA10 was the “bolt in” subframe connectors. You can see these in the picture below on the bottom side of the “Tri Ladder” subframe connectors. The bolt in subframes helped quite a bit but not near as much as the weld in. The best bracing is to connect the rocker panels with the frame rails by welding a square tube at the rocker pinch weld and then using cross braces to connect that to the subframes welded to the front and rear frame rails. Number Four will get the “Tri Ladder” subframes offered in the Saleen Performance catalog seen below.
This is the latest version of the Saleen “Tri-Ladder” subframe assembly. The design has been modified by adding a seat support brace and doubling the number of cross braces between the subframe and the rocker jacking rail.
You have to remember that when these cars were built the 5.0 craze was hitting its stride and peaked in the late 90’s. So a lot of these designs were perfected over the years. The company sent me more cross braces than needed. An honest mistake I guess. I might use more than three cross braces. Not sure yet. The seat support is standard on just about all subframes offered for the Fox Mustang. There are also little triangular corner supports to weld in between the cross braces and the other pieces.