Shock absorbers play a critical role in damping all those portholes and imperfections on the road as you drive. They supplement what your tires, the suspension, and bushings do.
Shock absorbers work in tandem with springs (coil overs, leaf springs, or air suspension) to dampen the oscillation (bounce) affect your car’s suspension gets when it goes over portholes. They also ensure that your tires maintain almost constant contact with the road surface for better grip.
Since shock absorbers work as you drive, giving a definite estimate of how long it will take to replace them is almost impossible.
If your shock absorbers have a 60,000 miles warranty, the manufacturer expects them to start wearing by that time. Here are the variables
- Heavily used vehicles could cover this distance in a year and a half, others could take six years to cover the same mileage
- The rate of wear will be faster if you drive on unpaved roads or roughly surfaced highways
- How much weight your car carries most of the time will determine how hard the shock absorbers work hence how fast they wear out
While manufactures might give a 50K mile estimate for shock absorber replacement, having yours inspected frequently once they near this number is more responsible.
Inspect them for signs of damage once they hit 40K miles and have them inspected twice a year after that.
What Are the Signs of Bad Shock Absorbers?
Knowing when your shock absorbers need replacing is a great way to keep your car’s bushings and suspension in good condition. Here are the top signs and symptoms to be on the lookout for.
Leaking Fluid from the Outside of Your Shocks
Even though shock absorbers work by compressing air, they have an oil reservoir they use to increase their efficiency. Over time, the seal keeping the oil in place wears out.
When this happens, the oil will start leaking down the shock absorber’s shaft. Any signs of fluid and oil mean that your shock absorber is toast.
Sometimes, you can see this a bit late. You will not dust that has turned into gunk sticking on the top or bottom section of the shock absorber.
The Car Bounces More than Usual
This is an easy to implement test that you could either look for ideal conditions to replicate or just bounce the car on your own.
A car with good shock absorbers should bounce once or twice after going over a bump before settling down. The subsequent bounce should be slower than the previous.
Take note of how your car behaves when your drive over a bump. How fast does it settle down and stop bouncing?
You don’t have to drive over a bump fast to test your shocks. An alternative test involves bouncing the car yourself.
- Park the car on level ground
- Press the front of the car down and let it go before pressing it down again to initiate a bounce
- Let go and see how many times the car bounces before settling. Most cars will settle down with one or two bounces
- You can repeat the same test at the rear to see if the rear shocks are OK too
Car’s Read End Squats Under Hard Acceleration
While it’s normal for your car to slightly lift up the front under hard acceleration, your front and rear shock absorbers should dampen most of this move. The back of your car shouldn’t squat that much.
Squatting could mean the front strut and the rear shock absorbers aren’t damping roll enough to keep your car as close to level as possible.
The Front Side Dives More When You Brake Hard
Just as the back squats when you accelerate, the front will dive when you brake hard. The dive will be more exaggerated if your shock absorbers are worn out.
Again, it happens because the rear shock absorbers aren’t doing a great job damping the developing roll and are letting the rear of the car raise off the suspension more.
The Vehicle Feels Wobbly When Cornering
If one of your struts or shock absorbers is damaged, your car will bounce more on that side. This is because the shock absorbers can’t take the extra weight and control the car’s bounce efficiently.
The wobble gets worse if you corner at slightly higher speeds. This could make you uncertain and even make you lose control, especially on a slippery road. Damaged bushings, tie rods or even using soft winter tires in summer could also make your vehicle wobble as you corner.
Vehicle Feels Extra Fidgety at Highway Speeds
Again, with damaged shock absorbers failing to control vehicle bounce, your car will exaggerate the impact of every imperfection it rides over. Instead of bouncing just once or twice, it will bounce more.
This means bouncing from one imperfection will merge with a similar imperfection down the road. Your car will be constantly bouncing and jockeying down the road.
The ride will feel more fidgety and no longer as smooth as it used to be when you were riding on new shock absorbers.
Uneven Tire Wear
With all the bouncing around, it follows that your tires won’t be making perfect contact with the ground. This will translate to uneven tire wear.
Since the tires are not being firmly pressed to the ground, your tires won’t wear out evenly. This adds extra damage to your car giving you an extra repair bill.
Your Car Takes Longer to Stop
A longer stopping distance normally hints at a problem with your braking system. It could be worn-out brake pads or leaking brake fluid. On rare occasions, the problem could be your shock absorbers and struts.
When you brake, the front shock absorbers resist the car’s weight and push some of it mid to back of the car. This reduces the braking dive.
Additionally, it keeps some considerable weight on the rear wheels meaning they too can help with stopping the car instead of offloading more than necessary work to the front wheels.
Yes, the front wheels do most of the braking even under normal circumstances. However, your car will take longer to stop if more than the required weight is pushed onto them.
Damaged Suspension Bushings
This is a visible sign that you could notice when inspecting your car’s undercarriage. Your struts and shock absorbers have bushings at the point where they attach to other suspension and chassis parts.
If your shock absorbers are old, these bushings could be brittle, cracked, and damaged. While some people replace these bushings alone, replacing the entire shock absorber or strut is more responsible.
What’s the Difference Between Struts and Shocks?
Even though shocks and struts all do the same job in a car, they are not interchangeable. Their construction is different.
Technically, a strut is part of a vehicle’s suspension while a shock absorber isn’t. Struts affect a car’s alignment, caster angles, and camber. Shock absorbers are mere dampers.
Struts are a composition of a shock absorber and a spring. In most cases, the shock absorber runs through the middle of the coil-over spring. Additionally, the strut has more mounting parts that connect it to more parts of the car’s suspension while a mere shock absorber has the piston and bushing that attach next to permanent leaf or coil springs in a car.
What Causes Shock Absorbers to Fail?
Shock absorbers should last long. Actually, you should change your tires at least twice before you start thinking of changing your shock absorbers. However, this ideal scenario rarely happens.
Sometimes, shock absorbers will wear out faster than they should. Here are the top things that could accelerate tear and wear.
Mud Residue on the Shock Absorbers
When you offroad, all that mud you have fun playing in gets everywhere. Some very fine bits of it could cover your shocks and work its way into sealed places as they work.
This could drastically reduce your shock absorber’s lifespan. If you use your vehicle on a farm or offroad a lot, wash it very often and remember to powerwash the bottom and wheels to get rid of any mud.
Moreover, inspect your shock absorbers more often. 15,000 miles should be enough time to start inspecting them and be ready to replace them in case mud got to them.
Offroading and Driving on Dirt Roads
Driving on dirt roads puts a lot of strain on your shock absorbers. They have to deal with more bounce and get hot really fast. The constant stress makes them age faster.
That is why most hard-core offroading trucks have custom suspensions with bigger oil reservoirs to take more punishment.
If you know you frequent dirt roads, consider installing dedicated offroad shock absorbers. They will make your car ride smoother and reduce the costs of having to replace stock road shock absorbers more often.
Potholes and Poorly Patched Roads
Potholes and poorly patched or paved roads replicate the experience your shock absorbers will get on a rough road. The impact translated to you in the cabin might be less but the shock absorbers will surfer more because chances are you will be driving faster.
After all, it’s still a paved road with occasional blemishes.
ProTip: Such potholes on otherwise paved roads can cause more damage like warped rims, tire bulges and even tire blowouts. Be keen when driving on them.
How Much Does it Cost to Replace Shock Absorbers?
The cost to replace your shock absorbers or struts depends on the type and quality of replacements you decide to go for.
You can get good shock absorbers for as low as $300 per set. You can also spend up to $3500 to get high-quality performance shock absorbers for your offroading rig.
The labor costs will vary depending on your region and how much your mechanic charges per hour.
Should I Replace All Four Shocks at the Same Time?
Ideally, you should replace all four shock absorbers – just as you should when replacing tires or even brake pads.
However, if you are on a tight budget, you could get away with replacing a pair at a go. This means you can replace all the rear shocks at once and replace all the front struts at once later on.
Don’t replace one shock absorber at a go even if you only visible damage on that one. This will make the axle the shocks control unstable. This is dangerous. Axles should be in harmony with themselves.
What Happens if You Don’t Replace Your Shocks?
Failing to replace your shock absorbers is dangerous. Your car brakes badly and is harder to control. This makes it dangerous to you and other road users. While it can still move, it is a major hazard especially when it picks up speed.
Moreover, it will be more uncomfortable. The unsettled ride will be punishing to other parts of the suspension making you have to replace more than you should have when you eventually get to service it.