I have an older body on frame car that rides pretty bad and loud. Its got me curious how manufacturers make newer cars ride so smooth and quiet. I’ve done some googling but not found much other than obvious, general things like “rigid construction” and “more soundproofing”. I would love to find a website that goes deeper into it.
Body on frame car is very old (80’s).
Since then cars are unibody which means the frame part is integrated and spread across the body and floor parts.
Manufacturers have moved on to subframes. A strong U or boxshaped tube rail to fasten powertrain mounts, steering, suspension arm and all moving parts onto. They then bolt the subframe to the unibody with dampers and bushings to reduce NVH into the cabin.
For soundproofing, most windshields now have 2 panes with glue sandwiched between the 2, the pillars are filled with foam, door panels and the floor have strategically placed thick sheets of sound dampening,
As for smoothness, lots of cars have different suspension to do the job. The standard is the multi-link suspension( many control arm with different range of rotation and angles that together keep the wheel flat on the surface if you accelerate, Brake, corner) having as many arms as possible helps the ride stay smooth and quiet.