Ultimate Guide to Car Suspension
Car suspension is a function that many people take for granted. We expect our vehicles to soften bumps when we drive over potholes, effortlessly turn in the direction we steer the wheel and maintain traction with the road.
There’s a lot that goes into building a flawless car suspension, and, thankfully, it’s generally low-maintenance. However, there are important things you should know about your car suspension’s shock-absorbing properties.
In this guide, we’ll cover everything you need to know about understanding and maintaining your car suspension.
- What’s the Purpose of Car Suspension?
- Did You Know?
- Benefits of Car Suspension
- Types of Car Suspension
- Independent Suspension
- Semi-Independent Suspension
- Dependent Suspension
- Rear Suspension vs. Front Suspension
- Car Suspension Parts
- Shock Absorbers
- Joints, Bearings & Bushings
- Steering System
- How Springs Work
- Other Car Suspension Measurements
- Wheel Rate
- Roll Rate
- Weight Transfer
- Signs Your Car Suspension Needs Repair
- How to Change Shock Absorbers
- 1. Purchase New Shock Absorbers
- 2. Jack Your Vehicle & Remove the Wheels
- 3. Spray Shock Mountings
- 4. Remove the Old Shocks
- 5. Install the New Shock Absorber
- When Should You Check Your Car Suspension?
- Final Thoughts
What’s the Purpose of Car Suspension?
Car suspension is primarily about comfort for you, the passenger. When your car suspension is working correctly, it offers stability and friction between your tires and the road.
It’s also essential for proper steering, ensuring that your tires go where your steering wheel tells them to.
Long story short?
Car suspension is vital to all vehicles. If your car suspension is malfunctioning, it’ll not only cause you discomfort but could also impact your safety while driving.
Did You Know?
If you drive down a flat road without a single imperfection, you wouldn’t need a car suspension.
Of course, such perfect roads are hard—if not impossible—to come by. Even brand new paved roads have small bumps.
If your car suspension isn’t working correctly, the degree of discomfort will depend on just how bumpy the road is. Bigger bumps or dips in the road equate to more discomfort for passengers.
Benefits of Car Suspension
You now know that car suspension is essential for your comfort. But there’s more to it. Below are some other benefits of car suspension:
- Ease of steering, especially around corners
- Better stability
- Supports the weight of your vehicle
- Ensures tires maintain contact with the ground
Here’s a fun fact: the impact of a bad car suspension is included in some DMV written tests.
Three options are offered in the multiple-choice question: vehicle control problems, squealing breaks, and slack in the steering. Of course, the first answer is correct, but 13.14% of test-takers get this question wrong, according to the DMV.
Car suspension systems are responsible for maintaining comfort and equilibrium. Without its steering and stability qualities, your tires could tilt up off the road if you hit the brake hard or make a sharp turn.
That’s a scary thought and is why it’s important to keep your car suspension maintained. We’ll be covering car suspension maintenance and replacement shortly.
Types of Car Suspension
There are three main types of car suspensions. They are as follows:
- Independent suspension
- Semi-independent suspension
- Dependent suspension
Let’s take a closer look at each one.
Independent suspensions are the most common and comfortable type of car suspensions. It’s a versatile suspension, with each wheel reacting differently to road conditions.
In other words, the movement of one wheel doesn’t affect another wheel.
For example, picture one wheel of your car hitting a pothole. With an independent suspension system, the springs on that single wheel will work on absorbing the shock while your other three wheels work to maintain equilibrium according to the terrain they’re on.
As a result, independent suspensions make for a more comfortable ride and keep your vehicle as stable as possible.
Semi-independent suspensions are commonly used on vehicles with front-wheel drive. They offer a more compact and lighter suspension compared to the other two suspension types on this list.
Dependent suspensions are advantageous because they’re a more economical type of car suspension. However, they’ve gone out of style because of their solid axle design.
A solid axle design means that if one tire reacts to a particular road condition, the tire across from it automatically reacts the same. So, that pothole we just talked about will feel a heck of a lot bumpier if your vehicle has a dependent suspension system.
Rear Suspension vs. Front Suspension
No two cars are the same, and this is especially the case when considering car suspension for front-wheel versus rear-wheel-drive cars.
Front-wheel drive vehicles are less fussy, with the option to use several different kinds of beam axles and independent suspensions.
On the other hand, rear-wheel-drive vehicles require more complex independent suspensions. As a result, the rear-wheel-drive suspensions are more expensive.
When it comes to four-wheel-drive vehicles, the suspensions are typically similar between the front and rear wheels.
It’s important to note that four-wheel vehicles must have suspension for both the front and rear wheels.
Car Suspension Parts
You may be wondering—what kinds of parts make up a car suspension?
Car suspensions are located beneath the vehicle and serve as part of the chassis. The chassis is a term for describing the frame, steering system, tires, wheels, and suspension system.
There are a plethora of small parts that go into making car suspensions run well. And, depending on the type of car suspension you have, these parts can vary.
If you’re new to understanding car parts, make sure to head over to our Big List of Auto Parts. We’ll cover the basics, so you know what you’re talking about and looking at when looking at your vehicle’s parts.
Seven parts go into all car suspensions. They include:
- Shock absorbers
- Joints, bearings, and bushings
- Steering system
Let’s talk in more detail about each one.
Based on the list above, we should have painted a picture that car suspension systems are immense. Their size is due, in great part, to this system extending to the wheels.
While we’re on the subject of tires, keep them looking spiffy with our guide on the Best Wheel Cleaner for your vehicle.
It’s pretty easy to think of springs and understand how they would help with shock absorption. Coil springs bend and give in to impact when you drive over potholes and bumpy services. Thus, it makes the ride more pleasant for you.
You can’t have springs without shock absorbers. The role of shock absorbers is to lessen the impact of springs by limiting how much they move.
It’s a tough job, and, as a result, shock absorbers need to be changed once in a while. Furthermore, shock absorbers contain oil, which causes issues for your vehicle if a damaged shock absorber leaks.
The purpose of rods is to link parts of the car suspension system together. They’re metal and tough. Therefore, you shouldn’t have to worry about replacing them unless they’re damaged in an accident.
Joints, Bearings & Bushings
Phew, this is a mouthful! But joints, bearings, and bushings are vital because they’re what holds your car suspension system together. These parts are relatively low-maintenance, although they can loosen over time. However, keep in mind that bushings made of rubber are prone to wear.
If we’re getting technical here, the steering system isn’t directly a part of car suspensions. However, it works in conjunction with the wheels for turning. As you already know, an important aspect of car suspension systems is ensuring a smooth, wheels-on-the-road kind of turn.
The frame is responsible for supporting your vehicle’s weight and holding all the car suspension parts in place. It’s the largest part of a car suspension system by area and supports the engine.
How Springs Work
We’ve established that car suspensions involve springs. But manufacturers can’t just slap on any ‘ole spring. Instead, careful mathematics goes into determining the spring rate (also called suspension rate).
So, what goes into deciding the spring rate?
- The vehicle’s ride height
- Vehicle’s weight
- Type of spring used
Picture a car, an SUV, and a tractor-trailer. What are some initial thoughts that come to mind? Their weight and how far off the ground they sit are two characteristics, wouldn’t you say?
Keeping that in mind, consider that not all springs are created equal. Springs for tractor-trailers need to be much heavier to carry weight than springs for an SUV or car.
For mathematicians, the spring rate is a simple calculation—the change in spring force exertion is divided by the change in spring deflection from its resting position.
You might be wondering: what happens if springs are too hard or too “soft” for the vehicle it’s supporting?
Your suspension system would be useless since the springs wouldn’t be isolating your vehicle from the road like they’re supposed to.
Other Car Suspension Measurements
Spring rate may be the most obvious measurement when putting together the correct car suspension for a vehicle, but it’s far from the only one.
Below are some other calculations that go into car suspensions:
- Wheel rate
- Roll rate
- Weight Transfer
Now, let’s take a closer look at each.
Wheel rate measurements tie in closely with spring rates. The difference is that the wheel rate involves spring rates with the wheels included.
Generally speaking, wheel rates come out to be less than spring rates.
The roll rate focuses on lateral accelerations. It’s the study of how a vehicle’s weight rolls on its axis. As a general rule, higher role rates equate to faster and larger percentages of weight transfer.
Roll weight deals with weight transfer, so you may be wondering: what exactly is weight transfer?
Weight transfer happens during acceleration, turning a corner, and braking. The amount of weight transfer itself is dependent on the following four items:
- Distance between wheel centers
- Vehicle mass
- Quantity of acceleration
- Center of gravity height
There are two different kinds of weight transfers—unsprung and sprung.
As their names imply, unsprung weight transfers handle weight transfers that don’t involve springs. On the other hand, sprung weight transfers calculate the weight of the portion of the vehicle resting on springs.
When talking about travel in relationship to car suspensions, it’s all about the measure of distance. Has your car ever bottomed out when you drive? Perhaps your fender has hit the road when you go over a speed bump too fast?
That’s a travel issue, which is a measure of the distance between the top and bottom of suspension strokes.
The purpose of damping in car suspensions is motion control of a vehicle’s shock absorber.
If you’ve ever been in a vehicle with deteriorating car suspensions, you may be familiar with the excessive up and down motion it makes when it hits a bump. That’s the role of damping—to literally dampen a bumpy effect in a short amount of time.
Signs Your Car Suspension Needs Repair
Shock absorbers in your car suspension system are continually being worn down when you drive. Therefore, you must change your shock absorbers every once in a while.
The frequency with which you need to change your shock absorbers varies depending on how often you use your vehicle and if you typically drive over smooth or uneven surfaces.
So, how can you tell if your car suspension needs repair? These are a few signs:
- If your vehicle feels like it slides along the road
- It takes longer to stop your vehicle
- Uneven wearing of your tires
Now you know how to identify when your car suspension needs new shock absorbers. Let’s take a look at how to change them.
How to Change Shock Absorbers
If you’re the DIY type, we’ve got good news for you—with a bit of time and practice, replacing your shock absorbers is easy.
If your car shows any of the symptoms we mentioned earlier, roll your sleeves up and get ready to pass on steep mechanic fees by following these steps.
1. Purchase New Shock Absorbers
Not all shock absorbers are the same, so don’t buy the first ones you stumble across. Instead, if you’re unsure of the kind of shock absorber you need for your vehicle, ask someone at a local auto parts store.
2. Jack Your Vehicle & Remove the Wheels
You’ll want to choose a flat surface where you can jack your vehicle. Once your vehicle is securely jacked, remove the wheels, and identify the shocks. The shocks may have a vertical bolt from within, or they may be on top with a horizontal bolt.
3. Spray Shock Mountings
The most challenging task of your shock absorber replacement is about to happen, but you can make it easier by spraying the shock mountings with a metal cleaner. WD-40 is an excellent option for this, as it will loosen things up before you remove the old shocks.
4. Remove the Old Shocks
Now we’ve arrived at the trickiest part. You’ll want to remove the old shocks by unfastening the bolts, turning them counterclockwise, and using spray such as WD-40, as needed.
Then, remove the shock from the suspension. Some vehicles will also require removing the knuckle by the brake assembly to do so. Your vehicle’s owner’s manual will let you know whether or not this is necessary.
Once these steps are complete, wiggle the old shock absorber of its bolts. The catch? It’s not so easy!
You may need to use pliers or bang the bolt with a hammer to remove the shock absorber.
5. Install the New Shock Absorber
Doesn’t it feel great to have the old shock absorber removed?
Now, you’ll need to perform the task above backward, sliding your new shock absorber back where the old one was. It should be a lot easier than getting the old shock absorber off.
Just as a word of caution, make sure to check your vehicle’s torque specs so that you don’t leave the bolts too tight or not tight enough.
Congratulations! It’s no easy task replacing shock absorbers for the first time.
And this may have you thinking—what other kinds of DIY projects can you do for your car?
Let us help you get started with our 20 easy tips on how to Make Your Car Last Longer.
Finally, keep in mind that these steps are for a shock absorber over one wheel. You’ll need to repeat these steps three times if all your shock absorbers are shot.
When Should You Check Your Car Suspension?
Normal wear and tear are the most common issue that breaks down car suspensions over time. That is unless you get in an accident. It’s common for car repair shops to overlook car suspension systems when checking for small fender benders.
However, this can cost you money in the long run. If you were hit by a vehicle and the other person’s insurance isn’t notified of a car suspension issue resulting from the accident, you’ll eventually get hit with the bill once your car suspension deteriorates.
Car suspensions are the pulse that keeps vehicles comfortable and stable. Maintenance is typically minor, but you should keep an eye out for signs of wear on the shock absorbers. By knowing how your car feels when it runs, you’ll easily be able to identify when a car suspension issue occurs.