Whenever I drive over speed bumps (or pot holes or whathaveyou) I notice that when the rear wheels go over, the whole car jumps up and down and clatters, a lot more so than the front wheels. I am pretty sure the shocks are not the issue here, partly because I've changed them and the behavior didn't go away and partly because the problem is not that the back is too bouncy, it's that it's too stiff. It almost seems like there's something wrong with the coil springs, but they look fine and I have no idea how to test them otherwise... Any ideas?
The car is an Acura Integra from '93, a sporty hatchback.
A fairly common issue on cars with strut suspension are broken springs. As the strut wears it looses its ability to control spring dampening. This allows the spring to compress and expand faster and farther than designed. Over time the spring weakens and breaks. The break many times occurs at the very last turns of the spring and may go unnoticed. Look at the very bottom of the spring and see if the end appears as a clean edge or a jagged break. You should have the same number of coils on both sides. The shortened spring acts stiffer than the stock spring resulting in a harsher ride. Another source of banging maybe worn or damaged strut mounts ( in your case this should have been detected during replacement). You may also have worn suspension bushings that are allowing extra movement resulting in the banging. Don't forget to rule out a broken exhaust hanger letting the exhaust bang on the floor.
Other suspension parts have bushings like a trailing arm on the rear. Suggest that you take a look at the function of the wheels using a second jack on the suspension when tge body is jacked and backed up with stands. Suspension bushings fail as well.
Also if you have any torsion bars check them as well.
One additional thought..around here many alignment shops and tire shops which do alignments, will do a courtesy check, where the lift the car up, and poke at the suspension with a pry bar. They don't charge. This gets experienced eyes on the suspension.
Its basic law of gravity here as for most of the cars engine are located at the front so they are heavier at the front so the front wheels remain calm and composed compared to rear of the car.You would experience the that your car would stop bouncing if you stuff your car's boot with luggage.