About the stiffness of the 404 sedan, I agree that it could have been better. When these cars get a little rusty, they lose all torsional stiffness and using the factory jack (if the mounts have not detached) will result in unopenable doors when the car is off the ground. The daily driver KF2 sedan that I was forced to scrap in 1990 was like this.
On the other hand, the 404 Coupé is an immensely stiff shell, even when rusty. It's got all of the reinforcements of the cabriolet (huge frame channels inside the rocker panels, welded up fenders,...) plus a strong permanent roof. That's the reason these cars weigh 55 kg more than the sedan.
I suspect that the 504 sedan/Coupé had the same thing going, and perhaps that's one reason that Peugeot started using the 504C for its rally car in 1976 (the V-6 might have had something to do with it too).
I don't know the 403 well enough to comment meaningfully on it, although the egg-shape of its roof seems to be stronger-looking than that of the square-rigged 404.
I still love the 404 though, and if I build a 404 KF2 rally car someday, it'll be a sedan, of course!
On the other hand, the 404 Coupé is an immensely stiff shell, even when rusty. It's got all of the reinforcements of the cabriolet (huge frame channels inside the rocker panels, welded up fenders,...) plus a strong permanent roof. That's the reason these cars weigh 55 kg more than the sedan.
I suspect that the 504 sedan/Coupé had the same thing going, and perhaps that's one reason that Peugeot started using the 504C for its rally car in 1976 (the V-6 might have had something to do with it too).
I don't know the 403 well enough to comment meaningfully on it, although the egg-shape of its roof seems to be stronger-looking than that of the square-rigged 404.
I still love the 404 though, and if I build a 404 KF2 rally car someday, it'll be a sedan, of course!