Optimising Shock Absorber Performance

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09 Sep 2019

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Shock absorbers are responsible for maintaining tyre-to road adhesion for good grip and braking. If they, or other suspension components are not working, contact is compromised which can result in longer braking distances and poor handling. This is especially dangerous during critical avoidance manoeuvres.

Vehicle safety systems like the anti-lock braking system (ABS) and traction control can only function perfectly if all suspension elements are in good working order. Therefore, it’s vital that the suspension system is kept in good condition.

Check All Parts

When replacing shock absorbers, all other parts of the system should be thoroughly inspected for wear.

Check the condition of ball joints and rubber-to-metal components such as control arm bushes and suspension top mounts before dismantling. Wear to these parts can lead to excessive play in the joints, subjecting the shock absorber piston rod to stress beyond its design limits.

This can cause a fatigue fracture where the threaded pin joins the piston rod. Another potential problem is side loading of the piston rod rapidly wearing both its chromium plating and its oil seal causing the shock absorber to leak.

Installing Shock Absorbers

A regular suspension test is recommended every 12,500 miles to ensure that the suspension system is working properly. However, it is important to keep in mind several symptoms that are indicative that shock absorbers should be replaced:

• “Bottoming out” of shock absorber
• Rattling noises
• Worn piston rod, seals or valves
• Shock absorber action is too soft or firm could be indicative that it is incorrect for the vehicle
• Poor road behaviour as the damping action has deteriorated
• Unusual tyre wear

It is best to replace shock absorbers in pairs alongside the ancillary items (spring assisters and gaiters). This is because the damping variation between new and used shock absorbers will become very apparent during critical times like avoidance manoeuvres.

Transport Tips

If moved or stored in a horizontal position, air may reach the working area of double-tube shock absorbers. This air can easily be expelled by compressing and extending the shock absorber several times with the piston rod at the top. The shock absorber can also “bleed itself” automatically after being fitted into the vehicle correctly and driven for a short time.