How your car works - Active Suspension

How to make your car handle better at the flick of a switch
Active suspension (first used in racing cars) is a relatively new development in the motor car. Essentially its job is to deliver better road handling characteristics for different driving conditions.

What does it do for me?
Well, it is a system that when functioning correctly has the effect of what amounts to the handling characteristics of a sportscar with the feel of a big luxury car. This dual role is achieved by using a control system that will (when provoked by hard driving or when manually switched) adjust the suspension to give a firmer ride and more "feel". If you've got it in your car there may be a switch close to the gear lever that will enable you to manually switch the suspension from a soft to a hard ride setting or "cruise" to "sport". Some systems are also controlled automatically, allowing you to simply concentrate on enjoying the car. In most cases if there is an active part in the suspension then this will often mean there is a hydraulic oil reservoir (although some operate by air pressure) under the bonnet which may need level checking occasionally. Check your handbook or ask your Unipart Car Care Centre dealer.

But how does this wonderful new technology work?
There are several systems in use but the more popular ones work by using hydraulic pressure to control the shock absorbers, car's ride height and influence the behaviour of the car. Sensors automatically monitor vehicle road speed, steering wheel position, acceleration and body movement and relay this information back to the central control unit which will adapt the suspension settings to give the most suitable ride and car control at all times.

In its automatic version this is all done without you really being aware of too much. It would probably be helpful if we look at an example: the car approaches a corner at a high speed and is in danger of losing control through excessive body roll.

The roll sensors will notice this and the active suspension system will activate and provide an opposing force to minimise the car leaning over (body roll), so increasing the car's ability to corner more efficiently and safely.

Sounds clever, doesn't it? It is important to remember that active suspension systems are only designed to allow better handling and a more comfortable ride. They can't do much about a situation that is beyond their capabilities and must not be considered fool-proof. If the car is taken beyond its limits, like anything else, it will more than likely result in an accident.

What happens if it goes wrong?
If the system was to fail in any way there is very little chance of it becoming dangerous to use. Fail-safe functions are built in, for example the shock absorbers would more than likely revert to a softer setting than a harder one, allowing you to drive the car safely until the problem can be rectified.

However if the system does fail, it would almost certainly be something that is beyond the scope of a DIY mechanic. Because electronics and hydraulics are extensively used to operate it, any problem is best left to your local garage who will have the ability, training and tools to diagnose and rectify the fault.

If a fault occurs in the system a warning lamp will display on the dashboard alerting you to the fact that a problem exists. Greater care will need to be taken when driving with a fault in the system but with care you should have no problem in getting to a garage.

Caring for your Active Suspension System

• Care must be taken when driving with Active Suspension. The car's ability to corner at higher speeds can lead to overconfidence. The car is still capable of losing control through the tyres losing grip on the road surface. Please remember to always drive safely and well within the car's capabilities (unless you're on the racetrack).
• If you become aware of a fault with the suspension system don't ignore it. Take the car right away to a garage for them to diagnose the problem as soon as possible. Remember it can seriously affect the car's handling.
• You should try to be aware of any signs of fluid leaking from the shock absorbers. If you spot this it is wise to take your car to a garage to be inspected. Each time that the car has a major service they will check for leaks from the system anyway of course.