How to check your car's shocks for wear

Keeping the ride pleasant on your car is the work of a double act. You have the springs of course, but then you have the shock absorbers, which… well, they absorb shocks. Without them the car would just be a wobbly mess and the springs would compress at the mere mention of load or a rough surface.

As such, your shocks are very important indeed. But how do you know when you need to replace them, and when that time comes around, how do you go about it? Worry not, as Haynes has your back.

Where are your shock absorbers?

Every car is different. That said, the most common style of suspension is the MacPherson strut, which means the shock is part of the strut structure itself. It sits within the spring, which is a great design as it saves a great deal of space. O\f course, other cars differ, so do check your Haynes manual.

As for the rear, MacPherson is again common. However, so is a separate shock. You’ll see it bolted at the lower end to the beam/axle and bolted at the top to a mount on the body. The spring will sit in separate ‘cups’.

When should you change your shock absorbers?

There is no hard and fast rule to how long your shock absorbers should last. Every car is a different weight, every car is driven by a different person, and every car is subjected to different road conditions and surfaces.

Despite this though, we can say that in larger cars with age-appropriate mileage, you’re looking at around five years of general use. If the car had had a gentle, low mileage life, that can increase.

Small cars with average to low mileage could see ten years out of a set of shock absorbers. If a car has higher than average mileage, then obviously the life expectancy goes down.

How can you tell your shocks are gone?

Remember when your Dad was looking at used cars, and he’d lean over one corner of the vehicle and bounce it? Guess what? He was checking the shocks. It’s the simplest way. Push the car down and it should rise back up and stay. If it wobbles about like jelly at a kid’s party, the shocks are goosed.

The other way to check if they’re on their way out is to get under the car and have a look. Shocks work via pressure acting upon an oil within the shock body. Shocks are sealed units. So, if you look underneath and there is a misting of oil or even worse, an obvious leak, then that means your shocks are failing.

Finally, there’s the way the car drives. Even the most softly suspended of cars will have some firmness to it. It has to, that is what functional suspension does.

So, if the car it rolling excessively out of corners, if it’s wobbling about when you brake or accelerate, and if it generally feels ‘disconnected’ to drive, shocks could well be to blame.

What tools do I need to change my shocks?

What tools do I need to change my shocks?

Happily, you shouldn’t need any specialist tools to change your shocks, with the exception of a spring compressor. The norm is for the front is three bolts at the top of the strut securing it to the inner wing, while at the bottom a larger nut and bolt, somewhere around the 18mm mark, will pinch the shock into the hub carrier at the bottom.

Be warned though, these bottom mounting can build up with corrosion and road dirt and as such, be a nightmare to get out. Use lots of penetrating oil it prior. Only use heat if the old shock is definitely going in the bin, otherwise you’ll ruin it.

Once the front strut is out, you’ll need to compress the spring and remove the strut top, which is usually held on by one bolt. Be warned though, spring compressors are not for the faint of heart.

A car spring under tension quite literally has the potential to kill you, so be slow and be careful. If in doubt, take the strut assembly to a garage who will happily separate the parts for a tenner.

As for the rear, it’s just nuts and bolts again, basic tools only. Jack the car up and you should be able to unbolt the shock with relative ease.

Just be sure to have jacked the car up enough to take the tension/load off the spring. You don’t want that pinging out. And again, a soak in penetrating oil won’t hurt things. But as ever, check your Haynes manual.