BMW 640i Car has bouncy and unstable ride Inspection at your home or office.

Common reasons for this to happen:

These are the primary components of the suspension system that can cause a bouncy or unstable ride, as well as some other potential culprits:

• Damaged shock absorbers: Shock absorbers are exactly what they sound like -- parts of your suspension system that absorb shock. The shock absorbers connect the suspension to the frame of the car. They are made up of a cylinder filled with a liquid or a gas. As the wheels and the suspension are subjected to force and impact from the road, the cylinder in the shock absorbers moves back and forth, and is met by resistance from the gas or liquid. This resistance limits the impact of the force, and makes it so that the body of the car receives very little of the impact that the suspension feels. When the shock absorbers are damaged, there is no absorption connecting the suspension to the body, and all of the bumps in the road are felt by the passengers in the car.

• Broken strut assembly: The strut assembly is essentially a modified shock absorber. Modern vehicles feature shock absorbers for the rear wheels, and strut assemblies for the front wheels. Strut assemblies are shock absorbers that have coil springs in the cylinder, along with the normal gas or liquid. These coil springs help further the assembly’s ability to absorb shock. Since the front wheels almost always bear the weight of the vehicle’s engine, this extra element of shock absorption is key for a smooth ride.

• Poorly lubricated suspension system: Like most parts of your vehicle, the suspension system relies on proper lubrication in order to work effectively. If the suspension oil is either contaminated, or leaking, the suspension will not be properly lubricated, and the pieces will not move smoothly and effectively. When the suspension cannot move smoothly, it is unable to absorb as much road impact as it should.

• Overinflated tires: It’s important that your tires remain well inflated, but they can sometimes be overinflated. Too much air in the tires results in a bumpy and unstable ride, as the tires are unmalleable, and do not absorb any of the impact from the road. Imagine a skateboard (which has very hard wheels) rolling across tarmac, versus a soccer ball, which is much softer. The skateboard will bounce aggressively, while the soccer ball will roll smoothly. However, if you notice the uncomfortable ride occurring right after adding air to your tires, that doesn’t mean that the tires are overinflated. If the tires had previously been underinflated, they would have covered up any failings in the suspension system. So you may have properly inflated tires that are exposing a suspension issue.

• Bulging tires: Tires can sometimes acquire bulges that make them very misshapen. These bulges directly impact the smoothness of the ride. If you notice that the bounciness while driving is a little sporadic, this may be the issue.

• Warped brakes: When you press your brake pedal, the brake pads apply pressure to the brake rotors. This pressure causes friction, which is what makes your vehicle slow down and stop. When the rotors or pads become warped, this friction becomes unstable and bouncy, and your car will bounce and shake when you brake. If the stability of your vehicle is tied directly to whether or not you are braking, then chances are you have warped brake pads or rotors.