Shock absorbers are what stop your truck from bouncing after a bump. A lot of people think it is just about comfort. The reality is that worn-out shocks directly affect your handling, your braking and your tire wear.
In summer, with long highway distances, worn shocks turn every trip into a chore and wear out the rest of your suspension early. At Ressorts Laval, we see the difference every day between a truck with healthy shocks and one that dances down the road.
What a shock absorber really does
The spring (leaf or air) absorbs the impact. The shock controls the rebound. Without a shock, your truck would bounce endlessly after every bump. A worn shock lets the wheel bounce, which means the tire loses contact with the road at times. Less contact means less traction and less braking.
Inside, a shock is a cylinder filled with oil. As the wheel moves up and down, a piston pushes the oil through small calibrated orifices. That resistance turns the energy of the movement into heat, and that is what calms the spring’s rebound. As it wears, the seals let the oil leak out and the orifices no longer control anything: the shock becomes nothing more than a rod sliding in an empty tube.
Signs of worn shocks
- The truck keeps bouncing after a bump instead of settling
- A floating feeling at highway speed
- The nose diving hard under braking
- Tire cupping, regular scalloped dips across the tread
- Visible oil leaks on the shock body
The floating feeling at highway speed is often the first thing you notice on the road in summer: the front of the truck feels light and you are constantly correcting. Tire cupping is the sign you spot afterward, and it is often the most expensive one, because it eats into tires that are still nearly new.
💡 The bounce test: push down hard on a corner of the truck and release. A healthy suspension comes back up and settles in a single motion. If it bounces two or three times, your shocks are probably done.
⚠️ Warning
Worn shocks lengthen your braking distance because the tires lose contact with the road. On a fully loaded truck, a few extra metres can make all the difference.
How we test shocks in the shop
The bounce test gives a good idea, but in the shop we go further to be sure:
- Visual leak inspection: a shock that is oily along its whole length has lost its seal
- Temperature check after a road test: a working shock gets warm, a dead shock stays cold
- Inspection of the top and bottom mounts and bushings, which wear out too
- Road test to reproduce the float and the nose dive under braking
This check lets us tell a truly worn shock from a worn mounting bushing that makes a similar noise. It is the difference between replacing the right part and installing new shocks that were never the problem.
How long shocks last
On a heavy truck it depends a lot on use and roads. In Quebec, with our winters and rough roads, shocks wear faster than elsewhere. We recommend having them inspected at every PMP and planning replacement once the signs appear. They always wear faster than the springs, and a truck that runs job-site roads wears them out faster still.
| Repair | Price range |
|---|---|
| Shock absorber replacement (pair) | $300 to $800 |
| Complete suspension inspection | included with diagnosis |
Why always replace in pairs
Like brakes, shocks are replaced per axle. If you put a new shock on one side and keep the worn one on the other, the truck behaves unevenly under braking and in corners. You lose part of the benefit and wear the new one out faster. A new shock working next to a soft one has to work harder and tires out before its time.
The domino effect on the rest of the truck
A worn shock never stays an isolated problem. The bouncing wheel hammers the leaf springs, the bushings and the mounts, which then wear out faster. The tires develop cupping and have to be replaced early. With every bump, the energy the shock no longer absorbs gets taken up by the other parts. That is why replacing shocks on time almost always costs less than waiting: you are protecting far more expensive parts.
Frequently asked questions
Can worn shocks wear my tires?
Yes. A done shock lets the wheel bounce, which creates cupping wear. It is a classic sign.
What is the difference between a spring and a shock?
The spring supports the weight and absorbs the impact. The shock controls the spring’s rebound. They work together.
Can I drive with a leaking shock?
The truck will roll, but its handling and braking are compromised. A leaking shock has lost its oil and no longer does its job.
How many shocks does a heavy truck have?
It depends on the configuration, but generally two per axle. A road tractor often has four to six total.
Is a small amount of oil seepage serious?
A light damp trace can be normal. It is a clear leak, with the shock oily along its whole length, that tells you it is done and needs replacing.
Do new shocks really improve comfort?
Yes, and above all safety. You get back a truck that settles quickly, brakes straight and tires the driver less on long distances.
Is your truck floating or bouncing?
Have your shocks inspected before they wear out your suspension and tires. At Ressorts Laval, we have diagnosed and repaired heavy truck suspension since 1971.
Call us at 450-661-5157.