If you have noticed that your car is starting to give you a bumpy ride, there is a good possibility the rear suspension has become rusted or worn out. If you think this may be the case, perform the following three tests to see if the rear suspension is going bad.
Drive Over A Speed Bump
The first test for testing your car's rear suspension is to find and drive over a speed bump. If the suspension is going bad, the back end of the vehicle may hit bottom or drag after the back tires clear the bump.
When you perform the test, do not speed up as you go over the bump. Instead, slowly go over it. If you go too fast and the suspension is worn out, you run the risk of crashing the back end of your car into the pavement, possibly breaking the coils or axle.
Perform A Bounce Test
Another way you can test to see how well your suspension is working is to perform a bounce test. To perform this test, situate the car on a flat surface, shut off your engine, then put the vehicle in park.
Go to the back of your car, and push the back down as far as you are able. Then, quickly let loose. When the suspension is in good condition, the car should only bounce once or twice. However, if the car bounces several times after you release it, this is a sign that the suspension's coils are either leaking or rusted.
Look Under The Backend Of The Car
If one or both of the above tests show signs that the rear suspension has an issue, visually inspect the shocks and coils by looking under the rear tires. One thing you should look for is rusted areas. If the rust covers most of the coils, they will most likely need to be replaced.
Also, you need to check for signs of fluid leaking out of the shocks. You may see a few drops dripping on the ground, or the shocks and coils may be covered with the fluid, depending on how bad the damage is. This will need to be examined by a mechanic to see what is causing the issue
If the tests above prove positive, your car's rear suspension may need to be repaired or replaced. You may want to take the vehicle to an auto repair shop to have them inspect the suspension and discuss with you options for fixing the problem.