Banishing a bumpy ride

A vehicle’s shock absorbers are essential, safety-critical components that should always be in top working order – and genuine…

When a vehicle accelerates, brakes, or corners, it is the shock absorbers that control the movement of the suspension and keep everything in check. Even one worn, or faulty, shock absorber can result in uneven body movement and loss of control.

Not only do they dampen and control the excess energy in a vehicle’s suspension (generated by the road) they also ensure optimum grip in corners and under braking. Furthermore, shock absorbers ensure occupant comfort by reducing, or eliminating, vibratory motions, due to uneven roads.

A faulty, poor-quality, or broken shock absorber will cause a vehicle’s wheels to bounce up and down rapidly and continuously, even on apparently smooth roads, leading to dangerously scuffed tyres.

To prevent unnecessary wear and tear on tyres and suspension components, it’s recommended that a smaller vehicle’s shock absorbers are checked at least every 50 000 km.

In the case of an average truck, it is suggested that shock absorbers are checked regularly and at every service. “On long-distance operations, it is recommended that vehicles and trailers are subjected to a ten-minute check before the start of the trip.

This inspection should include the inspection of the shock absorbers to see that they are in good working order and have not been broken, or come loose. They must be replaced when no longer functional,” suggests FOCUS technical correspondent, Vic Oliver.

As with many other vehicle components, replacement shock absorbers are frequently copied, or inadequately refurbished and sold at a price much lower than the original. When replacing shock absorbers, it is vitally important to ensure that original equipment components are used.

According to Bilstein South Africa, dimensional accuracy is critical and if the suspension is forced to work through an abnormal arc, it will cause incorrect suspension geometry under certain conditions, premature failure of rubber suspension bushings and mountings, as well as accelerated wear of other components such as constant velocity joints.

Recently, it was discovered that counterfeit versions of the company’s Airmatic spring/damper range (albeit designed for use in SUVs and saloons) have been in circulation. The fake versions are 40 mm too long and have air bellows (which act as the spring) that are an incorrect length.

Further, while the remote valve cylinder (which controls the transfer of oil into the main damping tube of the shock) is an original part, it has been harvested from a discarded assembly and installed in a completely non-functional manner – meaning the technology to control the damping rate has been rendered inoperative.

“If the crimped-on metal retaining band fails – which it could in the event of a sudden and harsh suspension movement – the ‘spring’ will collapse instantly, with potentially catastrophic consequences,” the company claims.

“Due to the safety-critical nature of the issue, consumers and the motor trade are advised to be aware of the dangers of attempting to repair these items, or fitting non-original replacement components,” it warns, adding that consumers need to exercise caution if the pricing of a shock assembly is very low.