What is a Shock Absorber
In order for a car to drive on anything other than perfectly smooth surfaces, all cars' suspension systems contain two key components: springs, to absorb the immediate impact of a bump or dip in the road, and shock absorbers. These prevent the car from 'bouncing' on its springs - more comfortable for passengers and, also, keeping the car's wheels in contact with the road.
How does a Shock Absorber work?
In simple terms, a Shock Absorber is an oil pump. A piston moves up and down in a cylinder filled with oil. The cylinder has small holes cut in it, allowing oil to flow through, allowing the piston to move. Because the holes are small, the piston provides resistance to the spring, absorbing the spring's natural 'bounciness'.
Do Shock Absorbers leak?
A shock absorber is a 'sealed unit' which means it requires no special maintenance. However, over time, the seals retaining the absorber's oil may fail, causing oil to escape. If this happens, the shock absorber usually needs to be replaced, because they will stop working when oil levels fall below a certain point.
Do Shock Absorbers need to be replaced in pairs?
This will depend on the condition of the other shock absorber. If a driver's side unit is worn, many garages will recommend replacing the equivalent passenger side unit. However, this is only really necessary if the second unit is also failing. You can do a 'bounce test' (to see if the car bounces after you push down on each corner) to find out.
What are the symptoms of a bad shock absorber?
A car with bad shock absorbers will bounce over bumps, and you may hear a knocking noise. It may 'bob' over bumps, like a boat.