Need to know

Key signs of a damaged suspension

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Why suspension components take so much punishment and how to spot when they need repairing

Steering & Suspension Need to Know Technicians 1 min read

In this piece, we’ll look at seven critical components within a vehicle’s suspension system, and what can go wrong with them.

Symptoms of poor or damaged suspension

One of the most obvious signs that a vehicle’s suspension needs attention is when your customer can feel bumps in the road more acutely. Suspension is a complex, multi-component system on the vehicle and this can add difficulty for the customer to describe the squeak, groan, or grind noise they’re experiencing. It’s best to replicate the fault on a short test drive with the customer if you can, to be sure you’re identifying what they’re reporting. This test drive time can be accounted for in the technician’s time, can increase first time diagnosis FTD, and can make all the difference in a positive customer service experience too.

An obvious symptom is when the vehicle drifts or pulls during turns. This means that the shocks are no longer up to the job of keeping the vehicle body stable when it’s turning. In extreme cases (and this is particularly true of commercial vehicles), this increases the chances of losing control of the vehicle, or even turning it over.

Problematic suspension can also increase stopping distances by up to 20% - a serious hazard. If your customer has noticed the vehicle’s bonnet lurching downwards while stopping, it’s a clear sign that the suspension needs attention.

Dampers

These are essential for keeping tyres in continuous contact with the road surface. A single worn damper can also increase a vehicle’s stopping distance by two metres at 30mph. Typically a damper will be replaced at regular servicing time if needed. There are various parts that accompany dampers that also need important attention, such as springs, and these should be replaced in axle pairs too.
Coil springs

These are one of the most prominent parts of the suspension system, and problems can be caused by continuous overloading. A broken spring is usually easy to spot with a visual check, and changing a spring that’s either broken or damaged is absolutely essential.
Air suspension

This is fitted to an increasing number of vehicles. It also uses natural rubber which wears out over time and may start to show small cracks. Air suspension springs are likely to need replacing every six to ten years but be aware that a long period out of use tends to increase the chances of failure.
Bushes

These are made of rubber to resist extremes of temperature and significant movement, as well as water and dirt. Over the years, bushes become brittle, with the rubber losing its flexibility. This can result in splits and tears. They can cause poor handling, vibration, excessive tyre wear and clunking noises. It’s a gradual process that does not necessarily cause a sudden failure, but even so, spotting the problem as it’s happening is essential if you’re servicing a vehicle.
Rods and linkages

These are the parts that connect the various elements of the suspension system together. They’re strong metal parts, and while they may occasionally corrode, they should usually last for a vehicle’s lifespan. The exception comes if they are in an accident or serious incident on the road, and if so, replacing them is essential.
Ball joints

Ball joints consist of a circular ball rotating within a lubricated socket housing, that’s both enclosed and protected by a tightly secured boot. Natural wear can occur that loosens the ball pin from its housing, and results in a clear knocking noise. Ball joints should be replaced in axle sets to ensure even distribution of suspension efficiency.
Shock absorbers

Shock absorbers work alongside springs to reduce the impact of bumps in the road and potholes. The shock absorbers support the springs by reducing their motion. Shock absorbers contain thick oil, and if this leaks, it can cause problems with other parts of the suspension system. Again, they should be replaced in axle sets in most circumstances.

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