If your vehicle is showing car bottoms out or scrapes the ground over bumps, here are the most likely causes and the parts you'll need to fix each one.
Shocks and struts control the bounce of your suspension. When they wear out or leak their internal fluid, they lose their damping ability, causing the car to bounce excessively and hit the suspension bump stops over bumps.
Springs support the physical weight of the vehicle. Over time and high mileage, they can lose their tension (sag) or snap entirely, permanently lowering the ride height and drastically reducing suspension travel.
Often mistaken for the suspension bottoming out, a loose plastic splash shield under the engine can hang down and scrape the ground when the car dips. This frequently happens if retaining clips are left off or broken during a recent oil change.
Rubber exhaust hangers can dry rot and break over time. This allows the exhaust pipe or muffler to hang lower than normal and scrape the pavement when driving over speed bumps or steep driveways.
On vehicles equipped with factory air ride, a leaking air spring or failed compressor will cause the vehicle to drop completely to the bump stops, resulting in a severely harsh, scraping ride.
If aftermarket coilovers or lowering springs were recently installed, the ride height may be set too low or the damping set too soft for normal street driving, causing the chassis to scrape.