Shock Absorbers and Struts
What are shocks and struts?
To soak up bumps in the road, your vehicle rides on four springs; one at each wheel. This provides a softer ride, but creates a new problem: By themselves, springs are bouncy and rather uncontrolled. (Think of a pogo stick!)
In order to control the movement of the springs, every vehicle utilizes shock absorbers (sometimes just called shocks) or struts. Shocks and struts are sometimes called “dampers” because of how they dampen the oscillation of your vehicle’s springs. Besides just preventing bounce, they also help absorb bumps; reduce body roll in corners; reduce “nose dive” under braking; and more.
A shock absorber is normally mounted separately from the spring in a typical suspension, while a strut is a more compact assembly that actually houses the spring within it. Both units perform the same job on your vehicle.
How do shocks and struts work?
In order to do their job, shocks and struts are designed to resist movement in the form of extension or compression. (Imagine a telescopic pole or brush handle that’s very hard to slide in or out.) In order to provide this smooth resistance, shocks are filled with an oil or fluid that, in order to allow the shock’s length to change, must be forced through very small holes in a piston on the inside. Internal valves control the movement of the fluid.
Most modern shocks contain a complex system of valve and baffles in order to provide velocity sensitive valving, which helps provide better handling without creating a stiff ride. These shocks can “soak up” quick/sharp bumps in the road, while stiffening up for larger and slower movements such as to resist body roll in a corner. It’s these quick-reacting and fine-adjustment valves that wear the fastest, which is why the old fashioned “bounce test” of pushing down on a vehicle’s bumper is no longer an accurate measure of your shocks’ condition.
Modern shocks are also pressurized with a gas such as nitrogen, which improves the performance – and also slowly leaks out over time.
When should shocks and struts be replaced?
While we’ve posted this article into the mechanical repair section of our website, it could have just as easily fallen into our maintenance section, because shocks and struts are a wear item on every vehicle. This means that they deteriorate over time, and require periodic replacement just like belts, spark plugs or filters do.
How often should your shocks be replaced? You’ll see the “every 80,000 km” interval everywhere; from automotive shops to car magazines. Where does this number come from? Unfortunately, it’s not from car manufacturers; it’s from companies that sell shocks and struts. Obviously, there’s a little bit of bias in that recommended replacement interval.
Since our goal is to keep your vehicle safe and reliable while also trying to best manage your cost of vehicle ownership, we recommend shock and strut replacement on a “vehicle by vehicle” basis. Some cars’ factory struts perform well for over 300,000 km, while other vehicles will require a replacement at less than 70,000 km! Based on how your vehicle drives, plus secondary indicators like tire and brake wear, our expert technicians will recommend new shocks when your vehicle truly needs them.
How do I know if my shocks and struts need to be replaced?
Here are some signs and symptoms that may indicate your shocks and struts are worn out:
- Your vehicle feels loose or bouncy; the suspension might make a “second bounce” instead of settling immediately after a large bump.
- Your vehicle rides rough, or seems to hit bumps very hard.
- The suspension is noisy; making clunking or knocking noises over bumps.
- People riding in the rear of the vehicle complain of “car sickness” or nausea.
- There is cupping wear on your tires. (See information further into this article.)
Visually inspecting shocks and struts:
When we inspect your vehicle’s suspension system, here are a few things that we’ll be looking for.
- Leaking shocks or struts indicate that the unit has failed: The loss of pressurized gas and oil inside the shock mean that it can no longer work properly.
- Worn bushings: Some shocks and struts have rubber bushings in them, where they attach to your vehicle. Like any other suspension bushing, these can deteriorate; crack; tear or become loose. Most of the time, these bushings are only available as part of a new shock or strut.
- Broken coil springs often result from reduced damping due to worn shocks or struts. A broken spring is often a great reason to install a new strut. Your old strut needs to be completely removed and disassembled in order to replace the spring anyway, so this is the perfect time to replace the strut as well with no extra labour involved.
Five reasons why shocks and struts should be replaced periodically:
When we think of a car with worn-out shocks, we usually imagine one that is very bouncy. Once you learn more about vehicles’ ride control systems, however, you soon realize that shocks and struts have a far more important job than just controlling bounce. Here are five reasons why every car or truck will eventually need new shocks:
1) Improved ride, handing and safety:
While we sometimes recommend new shocks and struts for many different reasons, customers who ask us for new shocks usually have one reason in mind: they don’t like the way their vehicle rides. Bumps in the road might feel harsher than before, or children riding in the vehicle could be getting “car sick”. Folks who tow trailers might not like how “soft” or uncontrolled their truck or SUV feels when loaded up. New shocks and struts would likely address these concerns.
This deterioration in ride control also affects safety, too. Worn shocks cause increased body roll; the top-heavy sensation where a vehicle “leans over” going around a corner. Worn shocks also cause more nose dive under braking, and can increase panic stopping distances by 5-10 metres!
2) Tire wear problems:
Worn shocks and struts don’t keep your tires in contact with the road the way they should, which can cause a condition called cupping of the tread. Cupping describes low spots in the tread that normally span 2 or more tread blocks. These low spots can usually be found all the way around the tire.
The first place we usually see tire cupping caused by worn shocks on a modern vehicle is the inside edges of the rear tires; especially if the tires have not been rotated enough.
3) Helping your other suspension components last longer:
Let’s pretend that your vehicle has reached 100,000 km and your ball joints have just been replaced. Did you know that even if we replace the ball joints with the exact same OEM parts, the second set will sometimes only last about 70,000 km? This is because the original ball joints had the benefit of living inside a suspension controlled by brand new shocks and struts, while the replacement ball joints live in a harsher environment; controlled by older shocks.
As your shocks and struts wear, this loss of suspension damping speeds up wear on your ball joints; control arm bushings; tie rod ends; and other suspension parts. If your shocks and struts are weak; leaking; or have over 150,000 km on them, you should consider replacing them to help increase the life of your other suspension components.
4) Make your brakes last longer:
Replace your rear shocks to save your front brakes? It’s true!
We’ve already talked about how properly-functioning shocks and struts reduce nose dive under braking. Nose dive is a bad thing, because it increases the amount of weight transfer to the front wheels as you stop. This extra weight transfer can over-work the front brakes, making them do more than their fair share of the stopping. This can lead to overheating of the brakes, and excess brake wear.
When we see a vehicle’s front brakes appear to have been overheated, but the rear brakes look totally fine, we usually inspect the rear struts/shocks next. This is because 60% of a shock’s internal valving is dedicated to controlling extension; in this case the “lifting” of the vehicle in the rear. The more the shocks wear, the more load is being carried by the front brakes.
5) Make your vehicle feel like new again.
Of all the repairs and services that we provide, nothing restores the “like new” feeling to a vehicle like replacing worn shocks and struts. Because shocks and struts deteriorate very slowly over time, we don’t notice the change in how our vehicle drives. With new shocks and struts installed, that new-vehicle “tightness” returns: bumps feel muted and further away; the vehicle feels more planted and controlled; it no longer “leans forward” under braking; and a lot more.
Bare struts vs complete strut assemblies?
Replacement struts are sometimes available as either a bare strut cartridge, or a fully-loaded strut assembly that also contains a new coil spring; upper mount; etc. Complete strut assemblies cost more than bare struts, but are quicker and easier to install because the old strut does not have to be disassembled in order to transfer over these other parts. On an older or higher mileage vehicle, installing complete strut assemblies makes sense, because the other wearing parts of the strut are likely worn as well. In situations where the strut and coil spring need to be replaced, the complete assembly is a no-brainer: it will usually cost less than the two parts purchased separately.
Replacing shocks and struts in Airdrie:
Installing new shocks and struts is a fairly straightforward job that involves a little bit of fairly physical work. Shock absorbers are usually just bolted in, and a set of front or rear shocks can usually be replaced in an hour or less. Struts are a little more complicated. Removing and installing a set of struts usually takes 2-4 hours on most vehicles. Once the strut is removed, the coil spring must be compressed using special tools, before the strut assembly can be taken apart. After replacing struts, a wheel alignment is usually required in order to restore proper suspension angles.
If you’re looking for an honest assessment of your vehicle’s shocks or struts, we’d be happy to help! If your shocks and struts need to be replaced, we can provide the best quality repair in the area, for a competitive price. Along with providing a careful and proper installation, we’re very picky about the parts we select for your vehicle. There are a lot of poor quality shocks and struts for sale these days, with many of them actually being a downgrade from your original shocks. We only use OEM or carefully selected premium aftermarket parts to ensure a truly lasting repair.
If you have any suspension-related questions, or would like an estimate on a suspension repair, please get in touch with us!