A shock absorber’s purpose and design is to help keep the tires on the ground on bumpy roads so that you, as the driver, can maintain control of the vehicle. Struts and shocks are designed the same, except that the weight of the vehicle is on the strut itself while a shock is merely a link between two suspension parts. They consist of a cylinder called the reserve tube that is filled with hydraulic fluid, another tube called the pressure cylinder within that cylinder, a piston that travels through the inner cylinder, and valving that meters the flow of fluid from one side of the piston to the other as bumps in the road are encountered. They are attached to the vehicle using bolts and rubber bushings.
Various things can go wrong with a shock absorber eventually so we are here to help you determine what the symptoms of bad or failing shocks/struts are so that you can make an educated decision as to whether or not you need to replace them.
1. Vibrations while driving
If the valving or piston seal inside the shock is wearing out then it may not sit properly, allowing fluid to flow uncontrolled past the valve or piston seal and thereby allowing every tiny bump in the road to cause an overreaction that you will actually feel with your hands on the steering wheel.
2. Swerving or nose diving while braking
If the valving or piston seal inside the shock is wearing out then the fluid flows uncontrolled and even the slightest steering wheel movement or the slightest brake application by the driver allows extreme movement of the piston within the cylinder. This means that if you take a right turn for instance then the weight of the vehicle will shift harder to the left during the turn and the driver will have to correct it, causing a swerve. When braking, the weight will shift farther forward than anticipated causing a nose dive.
3. Brakes take more time to stop the car
In addition to nose diving when applying the brakes, it takes extra time for the vehicle to take up all the piston rod length if uncontrolled and this adds time and extends the stopping distance required to come to a complete stop.
4. Uneven tire wear
A worn shock is unable to keep the tire firmly on the road surface. This causes a slight bounce as the vehicle moves over the road surface. The part of the tire that is in contact with the road will wear but the part of the tire that is not in contact with the road will not, causing uneven tire wear. As the tire rotates this contact area constantly changes with road speed, frequency of bounce, etc. The changing contact area will show up as excessively worn patches in the tire tread.
5. Leaking fluid
Sometimes the seals surrounding the shaft extending from the body of the shock will begin to leak and this leaking fluid will run down the side of the shock towards the ground. The loss of fluid will cause a loss in the ability of the shock to perform its function as there will be less and less fluid in the the chamber to work with.
6. Cracked bushing at attachment points
The shock has points at each end that allow it to be bolted to the vehicle. These attachment points have rubber bushings and if those rubber bushings crack or break out then a tapping will be heard as the vehicle is driving over bumps.