Shocks or Shock Absorbers
Shocks or Shock Absorbers are frequently used on cars and light trucks with standard suspension systems. Shocks may also be used on the rear of some cars front wheel drive cars that use McPherson strut suspension in front. Shocks offer resistance by forcing hydraulic fluid (oil) through valves in the piston as it moves up and down. Because the oil cannot be compressed, only a certain amount of fluid can be forced through these valves, which produces resistance to vehicle movement. Premium shocks are superior to regular hydraulic shocks because air in the shock is replaced by pressurized nitrogen gas. This prevents bubbles from forming in the hydraulic fluid. These bubbles, called foaming, reduce the ability of shocks to provide resistance and prevent bounce. Gas shocks also quicken the response of a shock’s movement, thereby increasing comfort and control.
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Purpose: Shock absorbers dampen movement of the vehicle’s springs as they compress and rebound during vehicle travel. Without shocks, a vehicle would continually bounce, making control difficult. Shock absorbers have a strong influence on vehicle control and handling and hold the tires to the road.
Maintenance Tips/Suggestions: Your vehicle’s shocks should be checked once a year, usually in conjunction with a wheel alignment. Under normal conditions, shocks wear out gradually and you may not notice incremental losses in ride quality, handling and control. Some signs that your vehicle may have worn shocks include excessive bouncing, rocking back and forth, drifting or nose-diving while braking, swaying, or cupping wear on the tires. If an inspection reveals the need for new shocks, consider premium shocks made especially for your driving habits. If you’re a pick-up or SUV owner, upgrading your shocks can bring a big improvement in overall ride quality and handling.
Struts are used on the front end of almost all front-wheel-drive vehicles. Technically known as MacPherson struts, they’re much more than a shock absorber with a different name. A strut integrates numerous suspension parts into one compact assembly, including the coil spring, spring seats, shock absorber, strut bearing, and steering knuckle. The shock absorber portion of the strut is the most commonly serviced portion of the strut assembly.
Purpose: Because it integrates different components into one assembly, a strut serves multiple purposes. With its spring, it can support the weight of the vehicle, while moving to adapt to road irregularities. The internal shock absorber dampens movement of the spring as it compresses and rebounds during vehicle travel. The strut housing serves as a structural part of the suspension system and connects the upper strut bearing to the lower ball joint, so that the entire assembly can pivot when the steering wheel is turned.
Maintenance Tips/Suggestions: Your vehicle’s struts should be checked once a year, usually in conjunction with a wheel alignment. Under normal conditions, the shock absorber portion of the strut cartridge wears out gradually, and you may not notice incremental losses in ride quality, handling and control. Some signs that your vehicle may have worn struts include bottoming out, excessive bouncing, rocking back and forth, drifting or nose-diving while braking, swaying, or cupping wear on the tires. If your car needs MacPherson strut service, it may also be a good time to replace the coil springs. Since they usually need to be removed when changing struts, you can save labor costs by installing new springs at the same time.