Worn shocks are a serious safety issue. But how can you tell when yours need replacing? The best way is to ask an auto repair shop—search DexKnows for one nearby. First though, here are a few clues to watch for and some shock absorber basics.
What are shock absorbers?
There’s a shock at each corner of your car or truck. They look like metal tubes, similar to the old manual bicycle pumps we once used, and they’re fitted between the wheel and the body of the vehicle. Their job is to control the movement of the springs. Without shocks you’d have a pretty bouncy ride and the wheels would have a hard time staying in contact with the road. That would be a problem because your braking distance would increase and you’d have trouble with the steering.
How do they work?
If you put a finger over the end of a bicycle pump, it gets really hard to push the rod into the tube. But move your finger slightly, so a little air can escape, and the rod slides more easily. That’s what happens in a shock absorber; only instead of air, it’s filled with oil; and rather than going out of the pump like the air, the oil flows through a hole in the piston. So the shock slows down the vertical motion of the spring, giving a smooth, safe ride.
How can you tell when shocks need replacing?
The part that wears is the piston. Because it wears very slowly, the deterioration is not usually noticeable. However, there are some signs that it might be time for new shocks.
- If the car fails the bounce test: Push down on the fender, then quickly let go. The car should rise up, overshoot, then settle at its normal height. If it keeps bouncing up and down, you need new shocks.
- If the tires are worn unevenly: If there’s excessive bouncing due to worn shocks, the tires will show cupping or scalloping on one side.
- If there’s oil leaking: Oil running down the side of a shock means it has failed and needs immediate replacement.
- If they’ve done more than 50,000 miles: Shock manufacturer KYB recommends replacement after 50,000 miles. Yes, they’ll go longer; but remember that braking and steering will be affected. Is that something you want?
- If they’re bent or damaged: Hitting a curb or large pothole can do more than rattle your teeth; it can damage suspension components such as shocks.
Get an expert opinion
It’s not easy to tell when shocks need replacing, so the best approach is to find an auto repair place specializing in suspension and steering and ask them.