Finding auto parts for my 4-wheel drive

Shock absorbers enable your car to handle properly especially when driving in difficult conditions. It is important to inspect your shocks every 24,000-50,000 km, and you should replace all four whenever you find one that isn't performing optimally. Your choice of replacement shocks is very important to your car's overall performance, especially if you carry heavy loads, tow trailers or drive in rough terrain. This article discusses important points to note when buying replacement shock absorbers.

1. Type

The following are some common types and their uses:

• Twin-tube design – this type is most popular for use in cars, vans, light trucks and SUVs. It is cost-effective and offers good control and handling when driving on most terrains.

• Mono-tube design – best suited for high-performance applications e.g. off-road driving or racing where the car is subjected to additional stress.

• Pneumatic – use air to dampen stress while driving. It has a sensor that monitors air pressure in the reservoir and turns on a compressor when pressure reduces

• Coil-spring – combination of shock absorber and spring coil. With some, you can adjust the ride height

• Gas-charged – have hydraulic fluid and are charged with nitrogen as the absorbing material. This prevents oil foaming, which usually reduces dampening power

2. Brand

It's best to go with OEM parts (same brand as the ones being removed) as they're usually the most durable with good warranty. High performance drivers are better served by brands which specialize in building performance shock absorbers. You can find out whether there are modifications that can make your new shocks work better. This isn't necessary with OEM parts, however.  

Consider that potential benefits of replacing your shocks may be lost if you don't upgrade supporting components, like springs and sway bars. Consult a specialist or your car manual for more information on this. You should also change the mounts as you replace shocks, because these wear out also. Ensure that you're using the same brand and type of shocks on all corners, and that you replace all four simultaneously. Failing to do this can create imbalance in the suspension system, which affects handling and control when you drive.

3. Spring rates

This is the rate at which the spring is compresses by application of weight or stress. If the spring is too hard or too soft when reacting to external stress, the shocks will be ineffective. You should consult your manual to find the ideal spring rate recommended for your vehicle. However, you should make modifications based on your driving habits. Shocks that are too hard will generally make the ride rough, while shocks that are too soft don't dampen external stress and can make you tyres lose contact with the road on rough terrain.