SUSPENSION – WHEN TO REPLACE?

“How do you know when your suspension needs to be replaced? Is there a simple home test? How do you test the leaf springs, coils and shocks? Do you have to replace the shocks more often than the springs?”

A vehicle’s suspension system does not have an infinite life span. Component wear may be gradual with replacement needed at some stage. Shock absorbers can fail suddenly, and springs can break. Here are some things to look out for:

Shock Absorbers:

Leaking or broken shock absorbers and shock absorber mountings are easy to spot. A shock absorber that has had an internal failure is harder to spot and will have to be removed from the vehicle for diagnosis. Most often though, shock absorbers lose their ability to dampen suspension movement effectively over time, wearing out like brake pads or a clutch plate.

Flat spots on your tyres over time are often a sign of worn shock absorbers. A worn shock absorber is unable to control the up and down movement of the wheel or axle, and the tyre is allowed to bounce up and down. This bouncing and skidding on the road causes flat spots. This uncontrolled movement also transfers into the cabin and your vehicle may progressively develop a rougher ride.

The most telling sign that your shock absorbers are worn may unfortunately manifest itself when you least expect it. Cornering at too high a speed or performing an emergency swerve in a vehicle with worn shock absorbers may cause the vehicle to break traction and start to spin, roll over or perform some similar uncontrollable action.

An increase in vehicle sway, nose diving under braking or squatting down in the rear under hard acceleration could also indicate worn shock absorbers. The old method of bouncing the vehicle by hand at each corner to test the shock absorbers often works on passenger vehicles but is harder to perform on your 4x4 with 2-inch suspension lift.

The only truly accurate way of testing a suspected worn shock absorber is to remove it from the vehicle, run it on a shock dyno and compare the graphs to the original specs. This is costly, time consuming and it is very difficult to locate a shock dyno, never mind the original specs.

It is important to note that worn shock absorbers do not affect the ride height of the vehicle.

Springs:

A broken or worn spring should be obvious to detect from the fact that the vehicle will lean down on the corner or axle of the affected spring/s. A worn or broken spring can no longer support the weight of the vehicle and its load resulting in loss of ride height and sag. In most cases, leaf sprigs also locate the vehicle axle to which they are attached. A broken leaf spring can therefore no longer locate the axle correctly.

In all cases, a worn or broken spring will affect the ride height of the vehicle in some way.

There is certainly no specific life span for shock absorbers or springs, and it is entirely dependent on how hard they work. A vehicle that only drives on smooth roadways could have its shock absorbers last the lifetime of the vehicle whereas that identical vehicle that lives on a farm will not be so lucky. As for the springs, provided they are manufactured correctly and the vehicle is never overloaded for any extended period, they should easily last the lifetime of the vehicle.